This document discusses primary retroperitoneal neoplasms, which arise outside of major retroperitoneal organs. It notes that 70-80% of retroperitoneal masses are malignant in nature. The document then categorizes and describes several specific types of solid neoplastic masses that can occur in the retroperitoneum, including mesodermal neoplasms (such as liposarcomas and leiomyosarcomas), neurogenic tumors, and others. For each type of mass, it provides details on prevalence, appearance on CT and MRI scans, characteristics, associated syndromes, and other relevant clinical information.
Imaging in small bowel tumors Dr. Muhammad Bin Zulfiqar
Here we will discuss CT and MR enterography. We will further discuss the use of negative contrast.
Four important tumors will be discussed.
Imaging in small bowel tumors Dr. Muhammad Bin Zulfiqar
Here we will discuss CT and MR enterography. We will further discuss the use of negative contrast.
Four important tumors will be discussed.
Testicular tumors are rare.
1 – 2 % of all malignant tumors.
Most common malignancy in men in the 15 to 35 year age group.
Benign lesions represent a greater percentage of cases in children than in adults.
Most curable solid neoplasm
Testicular tumors are rare.
1 – 2 % of all malignant tumors.
Most common malignancy in men in the 15 to 35 year age group.
Benign lesions represent a greater percentage of cases in children than in adults.
Most curable solid neoplasm
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
1. RETROPERITONEAL
MASSES
DR. SABHILASH SUGATHAN
Imaging of Uncommon Retroperitoneal Masses. Prabhakar Rajiah et al.
Primary Retroperitoneal Neoplasms: CT and MR Imaging Findings with Anatomic and
Pathologic Diagnostic Clues. Mizuki Nishino et al.
2. PRIMARY RETROPERITONEAL NEOPLASMS
(Retroperitoneal Masses not arising from major retroperitoneal
organs are- outside the major organs)
• 70%–80% are malignant in nature, and these account for 0.1%–0.2%
of all malignancies in the body.
• The retroperitoneum extends from the diaphragm superiorly to the
pelvis inferiorly and is situated between the posterior parietal
peritoneum anteriorly and the transversalis fascia posteriorly.
• The retroperitoneum is broadly divided into the
• anterior and posterior pararenal, perirenal, and great vessel spaces.
7. SOLID NEOPLASTIC MASSES
Solid neoplasms in the retroperitoneum can be broadly divided
into
four groups:
(a)mesodermal neoplasms;
(b)neurogenic tumors;
(c)germ cell, sex cord, and stromal tumors; and
(d)lymphoid and hematologic neoplasms.
8. MESODERMAL NEOPLASMS
• Most of the retroperitoneal neoplasms are of mesodermal origin, with
liposarcomas, leiomyosarcomas, and malignant fibrous
histiocytomas making up more than 80% of these tumors.
• Retroperitoneal sarcomas are commonly seen in the 5th and 6th
decades of life.
• These tumors are large at the time of clinical presentation and often
involve adjacent structures.
• Compression of adjacent organs causes formation of a pseudocapsule.
• The recurrence rates are high, and metastases to liver, lung, bones, and
brain may be seen
9. LIPOSARCOMA
Liposarcoma is the most common (33%) primary
retroperitoneal sarcoma.
Liposarcoma is usually large (average diameter, >20 cm) and is a
slow- growing tumor.
It is a predominantly hypoattenuating lesion on CT because of
its fat content. At MR imaging, it follows fat signal(high T1
intermediateT2 , loss of fat in fat suprsd MR).
The appearance of liposarcoma may be similar to that of a
lipoma, but liposarcoma has thicker, irregular, and nodular
septa that show enhancement after contrast material
administration.
11. .
Occasionally, a portion of the well-differentiated liposarcoma
undergoes histologic dedifferentiation and becomes more aggressive
and metastatic and then carries a worse prognosis.
At CT and MR imaging, these dedifferentiated tumors are depicted
as heterogeneous tumors with both fat and solid components and
show a lack of clear delineation
between solid and fat components
Calcification is seen in as many as
30% of cases and is an important
sign of dedifferentiation.
Variable signal intensity and
enhancement of the solid portion
may be seen.
12. LEIOMYOSARCOMA
Leiomyosarcoma is the second most common (28%) primary
retroperitoneal sarcoma.
It arises from retroperitoneal smooth muscle tissue, blood vessels,
or wolffian duct remnants and can grow to a large size (>10 cm)
before compromising adjacent organs and precipitating clinical
symptoms such as venous thrombosis.
It is more common in women, in the 5th to 6th decades.
Leiomyosarcoma can be predominantly extravascular (62%) or
intravascular (5%) in the retroperitoneum or can have
a combination of extra- and intravascular components (33%).
13. At CT, small tumors may be
homogeneously solid, but large
tumors have extensive areas of
necrosis and occasional
hemorrhage.
14. At MR imaging, these tumors have intermediate to low signal
intensity on T1-weighted images and intermediate to high signal
intensity on T2-weighted images, depending on the amount of
necrosis.
Mixed signal intensity and a fluid-debris level can be seen in
hemorrhagic lesions.
The presence of extensive necrosis in a retroperitoneal mass, with
contiguous involvement of a vessel, is highly suggestive of
leiomyosarcoma.
Metastasis to the liver, lungs, or lymph nodes occurs late in the
course of the disease
15. Approximately 6% of leiomyosarcomas arise from the IVC.
Most of these tumors have a large extravascular component that
makes it difficult to distinguish them from a secondary
involvement of the IVC with an extrinsic tumor.
16. The most commonly affected location is the segment between
the diaphragm and renal veins.
Tumors involving the superior segment of the IVC (above the
hepatic veins) may manifest with Budd-Chiari syndrome,
those of the middle segment (between the hepatic and renal
veins) manifest with right upper quadrant pain or tenderness or
the nephrotic syndrome, and
tumors of the inferior segment (below the renal veins) manifest
with
pain and lower extremity edema.
17. MR imaging typically shows an intraluminal intermediate-
signal- intensity mass on T1- and T2-weighted images, with
contrast enhancement.
The differential diagnosis includes benign thrombus,
angiosarcoma, and a tumor extending to the IVC from adjacent
organs.
While benign bland thrombus does not show any contrast
enhancement, leiomyosaroma of the IVC enhances on both
early and delayed (10-minute) contrast-enhanced images and
causes more expansion of the IVC.
Tumors from the middle segment of the IVC have a
better prognosis than those from other IVC segments.
18. MALIGNANT FIBROUS HISTIOCYTOMA
It is the third most common retroperitoneal sarcoma (19%) and
overall is the most common soft-tissue sarcoma in the body.
Malignant fibrous histiocytoma arises from primitive mesenchymal
elements, and 15% of these tumors occur in the retroperitoneum.
This tumor is more common in males (3:1), particularly in the 50–60- year
age group.
CT and MR imaging appearances are nonspecific and demonstrate a
large, infiltrating, and heterogeneously enhancing soft-tissue mass with
areas of necrosis and hemorrhage and with invasion
of adjacent organs.
19. Variable patterns of calcification can be seen (7%–20% of
cases) in the peripheral portions of these tumors.
The presence of calcification may help to distinguish malignant
fibrous histiocytoma from leiomyosarcoma.
20. Less Common Sarcomas.—
RHABDOMYOSARCOMA
Rhabdomyosarcoma has a bimodal distribution in the pediatric
population, with peaks in occurrence at 7 years and at adolescence.
CT or MR imaging shows a mass lesion with areas of calcification,
necrosis, and heterogeneous enhancement. Occasionally, high-flow
blood vessels may be seen.
Metastases occur in 10%–20%
of rhabdomyosarcoma cases
because of lymphatic or
hematogenous spread.
21. ANGIOMYOLIPOMA
It has varying amounts of blood vessels, smooth muscle cells, and
adipose tissue.
It is more common in females and can be associated with tuberous
sclerosis.
It occurs in a younger age group (25–35 years).
It is usually located in the kidneys but occasionally can be seen in the
retroperitoneum, solid organs, skin, or gynecologic tract.
At CT and MR imaging of angiomyolipomas, small tumors are
homogeneous and larger tumors are heterogeneous soft tissue masses
that typically contain a large amount of macroscopic fat and
hyperenhancing vascular soft tissue.
22. angiomyolipoma from liposarcoma.
Axial contrast enhanced T1-weighted fat-suppressed gradient-echo MR image shows a
retroperitoneal mass that contains intensely enhancing vessels (arrows)
23. MYELOLIPOMA
It is a benign tumor composed of hematopoietic cells and mature
adipose tissue.
Common in females, particularly in middle to old age.
The adrenal glands are the most common location for myelolipoma.
It is rarely seen in the retroperitoneum or presacral region.
At CT, myelolipoma is depicted as a heterogeneous mass with areas of
fat and enhancing soft tissue.
The attenuation value of fat
in myelolipoma is higher
than that of normal retroperitoneal
fat because of the mixed
hematopoietic tissue.
24. Extraadrenal myelolipomas are difficult to distinguish from
liposarcoma or other fat-containing tumors.
Liposarcomas are less well defined, are unencapsulated, and are infiltrative
without hemorrhage, compared with myelolipomas. Technetium 99m
(99mTc) sulfur colloid scintigraphy can be used to confirm the presence of
erythroid elements in myelolipomas.
25. NEUROGENIC TUMORS
Neurogenic tumors constitute 10%–20% of primary retroperitoneal
tumors.
Compared with the mesenchymal tumors, neurogenic tumors occur in a
younger age group and are more likely to be benign and have a better
prognosis.
Neurogenic tumors can originate from the
1. nerve sheath (schwannoma, neurofibroma, neurofibromatosis,
malignant nerve sheath tumors [malignant schwannoma,
Neurofibrosarcoma]),
2. ganglionic cells (ganglioneuroma, ganglioneuroblastoma,
neuroblastoma)
3. paraganglionic cells (paraganglioma, pheochromocytoma).
26. Neurogenic tumors are seen commonly
1. along the sympathetic ganglia, which are located in the
paraspinal region, and
2. in the adrenal medulla or the organs of Zuckerkandl (paraaortic
bodies)
27. SCHWANNOMA
Schwannoma, or neurilemoma, is a benign tumor that arises from
the perineural sheath of Schwann (neurilemma).
Schwannoma accounts for 6% of retroperitoneal neoplasms
and is more common than neurofibroma.
• asymptomatic
• females (2:1)
• 20–50-year age group
28. At CT, small schwannomas are round, well defined, and homogeneous, but
large schwannomas may be heterogeneous in appearance.
Calcification can be punctate, mottled, or curvilinear.
The nerve of origin is often difficult to identify.
After contrast enhancement, schwannoma demonstrates variable
homogeneous or heterogeneous enhancement
29. NEUROFIBROMA
It is a benign nerve sheath tumor that can occur as an isolated
tumor (90%) or as part of type 1 neurofibromatosis.
Approximately 30% of solitary tumors and 100% of multiple
tumors or plexiform neurofibromas are associated with type 1
neurofibromatosis.
• Common in Men
• 20–40-year age
30. At CT, neurofibroma is depicted as a well defined round
homogeneously hypoattenuating lesion (20–25 HU) because of the
presence of lipid-rich Schwann cells and adipocytes and entrapment
of adjacent fat. There is homogeneous contrast enhancement
Multiple well-defined homogeneous hypoattenuating neurofibromas (arrow) in a patient
with type 1 neurofibromatosis.
31. Tumors involving the neural foramen have a dumbbell shape with
expansion of the bone foramina or vertebral body scalloping.
Plexiform neurofibroma is seen as a large extensive infiltrating
mass.
32. MALIGNANT NERVE SHEATH TUMOR
Malignant nerve sheath tumors include malignant schwannoma,
neurogenic sarcoma, and neurofibrosarcoma.
Progressive enlargement, pain, irregular margins, a heterogeneous
nature, and infiltration into adjacent soft tissues are suggestive of
malignancy, especially when associated with type 1 neurofibromatosis
33. GANGLIONEUROMA
It is a rare benign tumor that arises from the sympathetic ganglia.
The retroperitoneum (32%–52% of cases) and mediastinum (39%–
43% of cases) are the most common sites for ganglioneuroma,
followed by the cervical region (8%–9% of cases).
In the retroperitoneum, the tumor is commonly seen along the
paravertebral sympathetic ganglia (59% of cases) or, less commonly, in
the adrenal medulla.
CT- circumscribed lobulated hypoattenuating mass that may surround a
blood vessel without narrowing the lumen.
Discrete punctate calcifications are seen in 20%–30%
34. GANGLIONEUROBLASTOMA AND
NEUROBLASTOMA
Ganglioneuroblastomais an intermediate-grade tumor that
has elements of benign ganglioneuroma and malignant
neuroblastoma.
Ganglioneuroblastoma is a pediatric tumor occurring in the 2–4-year
age group.
Imaging appearances vary, and the tumor could be solid or cystic with
solid components.
Imaging appearances vary, and the tumor could be solid or cystic with
solid components.
35. NEUROBLASTOMAmore commonly
seen in males and in the 1st decade of life.
Two-thirds of neuroblastomas are located in the adrenal gland, and
the remaining neuroblastomas occur along the paravertebral
sympathetic chain.
At CT and MR imaging, neuroblastoma is irregular, lobulated, and
heterogeneous and demonstrates coarse amorphous calcifications
and variable contrast enhancement, as well as invasion of adjacent
organs and encasement of vessels with luminal compression.
As many as 70% of patients have metastatic disease at the time of
diagnosis
36. PARAGANGLIOMA
(EXTRAADRENAL PHEOCHROMOCYTOMA)
Tumors that arise from the chromaffin cells of the adrenal medulla are
called pheochromocytomas, and those that arise in an extraadrenal location
(10%) are referred to as paragangliomas. Paraganglioma is commonly seen
in the 3rd to 4th decades, with no sex predilection.
In the retroperitoneum, the most
common site for a paraganglioma
is the organs of Zuckerkandl,
which are located anterior to the
aorta at the level of the origin of
the inferior mesenteric artery.
37. CT
• large well-defined lobular tumor with areas of hemorrhage and
necrosis.
• Punctate calcification is seen in 15% of cases, and a fluid-fluid level
can be seen that is due to hemorrhage.
• Because of the hypervascular nature of paraganglioma, intense
contrast enhancement is seen.
MR
• Signal voids can be seen with T1-weighted spin-echo
sequences.
• Variable signal intensity is seen on T2-weighted images.
• Although paraganglioma may be “bright” (Fig 16), the tumor is
usually complex and heterogeneous (because of hemorrhage)
38.
39. GERM CELL, SEX CORD, AND STROMAL CELL
TUMORS
Primary Extragonadal Germ Cell Tumors
Histopathologically, these tumors can be seminomas or nonseminomatous germ
cell tumors, which include embryonal carcinoma, yolk sac tumor, choriocarcinoma,
teratoma, and mixed
germ cell tumors.
The retroperitoneum is the second most common site of extra-gonadal germ cell
tumor after the mediastinum.
Extragonadal germ cell tumor is often seen in or near the midline, especially
between the T6 and S2 vertebrae.
A midline mass is more suggestive of a primary extragonadal germ
cell tumor than of metastasis.
At CT and MR imaging, the findings for primary extragonadal germ cell tumors are
nonspecific.
40. Nonseminomatous germ cell tumors are depicted as heterogeneous tumors with
areas of hemorrhage, necrosis, and heterogeneous enhancement.
41. TERATOMA
It is a germ cell tumor that originates from pluripotent germ cells
that have been interrupted in their normal migration to the
genital ridges.
Less than 10% of teratomas are found in the retroperitoneum.
It is third most common tumor in the retroperitoneum in children,
after neuroblastoma and Wilms tumor.
Common in females, with a bimodal age distribution (<6 months and
early adulthood).
42. Mature teratomas are predominantly cystic. Calcification and fat
can be seen. A fat-fluid (sebum) level and chemical shift between
fat and fluid are pathognomonic.
Mature teratoma.
Axial CT image of a 21-year-old woman with a mature teratoma shows a well-defined
heterogeneous mass that demonstrates fat (arrow) and teeth (arrowhead).
43. PRIMARY SEX CORD STROMAL TUMORS
Extraovarian primary sex cord stromal tumor is more commonly seen
in the pelvis along the broad ligament or fallopian tubes and is less
commonly seen in the retroperitoneum or adrenal glands.
Most of these tumors are granulosa cell tumors.
The imaging findings are nonspecific.
CT and MR images show heterogeneous solid tumors, with
heterogeneous enhancement
44.
45. LYMPHOID NEOPLASMS
Lymphoma
It is the most common retroperitoneal malignancy, accounting for
33% of all of these cases.
CT
Lymphoma is seen as a well-defined homogeneous mass, with mild
homogeneous contrast enhancement, that spreads between
normal structures without compressing them.
The aorta and IVC can be anteriorly displaced, producing the
“floating aorta” or “CT angiogram” sign.
Calcification and necrosis are unusual before therapy.
48. LIPOMATOSIS
Lipomatosis is a benign metaplastic overgrowth of mature
unencapsulated white fat.
Lipomatosis is seen commonly in the pelvis and along the perirectal
and perivesicular spaces and is seen less commonly in the
abdominal retroperitoneum.
CT and MR imaging
show excess fat in the pelvis crowding the anatomic structures, with
a few fibrous tissue strands but no soft-tissue mass or
enhancement.
49. A pear-shaped bladder is produced by symmetric compression and
displacement of the bladder caused by pelvic lipomatosis.
The lower portions of the ureters may be pinched medially,
with resultant hydroureteronephrosis.
50. RETROPERITONEAL FIBROSIS
Retroperitoneal fibrosis is an uncommon collagen vascular disease
of unknown cause that can mimic a retroperitoneal tumor.
Retroperitoneal fibrosis is typically idiopathic (>70% of cases)
and is likely autoimmune in origin.
It can be secondary to drugs, malignancy, hemorrhage,
inflammatory conditions, infection, radiation, chemotherapy, renal
trauma, and amyloidosis.
More common in males (3:1),
40–60-year age group
51. CT - irregular plaque like soft-tissue mass in the retroperitoneum,
located around the aortic bifurcation and extending along the iliac
arteries and involving the ureters, duodenum, pancreas, and
spleen.
It does not displace the aorta and IVC anteriorly, as lymphoma or
metastatic nodes often do, but causes tethering of these
structures to the underlying vertebrae.
52. Avid enhancement is seen in the active stages of retroperitoneal
fibrosis with little or no enhancement in the chronic phase.
MR-
high signal intensity on T2 WI in the acute phase of the disease,
with early contrast enhancement, and
shows low signal intensity in the chronic fibrosing phase, with
delayed enhancement.
53. ERDHEIM-CHESTER DISEASE
It is a rare non-Langerhans form of histiocytosis of unknown origin.
Extraskeletal lesions are seen in 50% of cases, with retroperitoneal
involvement seen in one-third.
Radiography shows characteristic
bilateral symmetric osteosclerosis
of the metaphyseal-diaphyseal
region of the long bones, with
sparing of the epiphysis and lesser
involvement of the flat bones and
axial skeleton.
54. Retroperitoneal involvement with Erdheim-Chester disease
characteristically produces a soft-tissue rind of fibrous
perinephritis surrounding the kidneys and ureters, which can result
in renal failure.
55. EXTRAMEDULLARY HEMATOPOIESIS
It is seen in hemoglobinopathies, myelofibrosis, leukemia,
lymphoma, and carcinomas.
The typical CT appearance is hyper- or isoattenuating round or
lobulated masses in the paravertebral region, with or without
macroscopic fat.
56. The MR imaging appearance is variable.
Low signal intensity can be seen on T1- and T2-weighted
images because of the red marrow or hemosiderin content.
High signal intensity may be found on T1- and T2-weighted images
because of fatty tissue.
Enhancement is variable and often mild and there is no associated
bone destruction or calcification.
57.
58. CYSTIC NEOPLASTIC MASSES
Cystic Change in Solid Neoplasms
Cystic changes may develop in solid lesions such as paragangliomas
and neurilemomas
Cystic Teratoma
CT shows a complex cystic mass, with areas of fat and calcification.
Lymphangioma
Lymphangioma is a developmental malformation that is caused by
failure of communication of retroperitoneal lymphatic tissue with
the main lymphatic vessels.
59. LYMPHANGIOMA
It can be seen in perirenal, pararenal, or pelvic extraperitoneal spaces
and can involve more than one compartment.
CT - large thin-walled unilocular or multilocular cystic mass with
attenuation values ranging from that of fat (caused by chyle) to that of
fluid.
Calcification is rarely seen.
60. An elongated shape and the involvement of multiple
compartments are salient features of lymphangiomas, particularly
those prone to recurrence.
The occurrence of septa, compression of intestinal loops, and a
lack of fluid in dependent recesses and mesenteric leaves
differentiate lymphangioma from ascites.
61. MUCINOUS CYSTADENOMA
CT and MR imaging show a well-
defined unilocular homogeneous
cystic mass.
Serous Cystadenocarcinoma
CT and MR imaging findings are
nonspecific and show a well-
defined cystic lesion with solid
intramural nodules,
62. CYSTIC NONNEOPLASTIC MASSES
HEMATOMA
Retroperitoneal hematoma can have a variable imaging
appearance, depending on its stage.
Acute and subacute hematomas have heterogeneous high
attenuation at CT and may be hyperintense on T1- and T2-
weighted images.
Chronic hematomas have
low attenuation on CT images
and low signal intensity on
MR images because of
hemosiderin deposition.
63. URINOMA
A well-defined cystic lesion is seen in the retroperitoneum, more
commonly in the perirenal space.
CT shows a well-defined fluid collection , with progressively
increasing attenuation caused by contrast-enhanced urine
entering the urinoma .
64. PANCREATIC PSEUDOCYST
Pancreatic pseudocyst is a collection of pancreatic fluid that occurs secondary to
acute pancreatitis.
CT shows a well-defined round or oval fluid collection with enhancing walls.
79. ?
Name the Retroperitoneal masses that grow and
extend into spaces between preexisting structures and
surround vessels without compressing their lumina
????