journal soft tissue

1. THE 2020 WHO CLASSIFICATION OF SOFT TISSUE
TUMOURS: NEWS AND PERSPECTIVE (PART 1)
PRESENTER: DR AMEERAH NABILAH BT AZHAR HILMY
SUPERVISOR: DR SITI NORASIKIN BT MOHD NAFI

2. OUTLINE
INTRODUCTION SOFT TISSUE UPDATES CONCLUSION

3. Mesenchymal tumor represent one of the most challenging field of diagnostic pathology
Refinement of classification schemes play a role in improving the quality of pathologic diagnosis and
therapeutic options
Published data indicate in sarcoma, rate of diagnostic inaccuracy ranging between (20-30%), however this is
not all due to pathologist negligence
There are factors that appear to impact negatively over both accuracy and reproducibility of pathologic
diagnosis
There are four main source of challenge can be identified
➢Rarity
➢Intrinsic complexity
➢Technological complexity
➢Lower impact of educational efforts

4. RARITY
➢Sarcoma Incidence 5 cases /100,000
➢Soft tissue malignancy are subclassified in approximately
70 subtypes
➢Many histotypes are exceedingly rare (0.1 cases /
100,000)
INTRINSIC COMPLEXITY
➢Mesenchymal tumours are characterized by specific
diagnostic peculiarities
➢The mere application of morphologic criteria of
malignancy used for epithelial cancer are not always
applicable

5. TECHNOLOGY COMPLEXITY
➢Diagnosis relies on complex combination of conventional
microscopic morphology, IHC and molecular genetic.
➢This acquires of molecular technology
➢It is quite intuitive that centralization of molecular
diagnostics in high volume centres is mandatory to
maintain high analytic quality
LOW IMPACT OF EDUCATIONAL EFFORTS
➢Despite education is fundamental role in increase of
diagnostic expertise, in field of rare cancers, its efficacy is
hampered

6. The WHO classification of soft tissue tumours, has introduced a profound change in its methodological
approach aimed to support a more rational therapeutic approach.
Major changes can be summarized as follows
➢Integration of morphology with IHC and molecular genetics
➢Involvement of a broad number of sarcoma expert pathologists
➢Precise definition of clinicopathological categories
➢Involvement of clinicians
The aim of this paper is to review the main advances contained in the current classification and also discuss
new perspectives that most likely will generate some debate in the years to come

7. CLASSIFICATION OF SOFT TISSUE
TUMOUR
Adipocyte tumours
Fibroblastic/ myofibroblastic tumours
So-called Fibrohistiocytic Tumour
Vascular Tumours
Pericytic (perivascular) Tumours
Smooth Muscle Tumours
Skeletal Muscle Tumours
Gastrointestinal Stromal Tumours
Chondro-osseous Tumours
Peripheral Nerve Sheath Tumours
Tumours of Uncertain Differrentiation
Undifferentiated Small Round Cell Sarcoma of Bone and Soft Tissue

8. ADIPOCYTE TUMOUR

9. WHO 2013 WHO 2022

10. ATYPICAL SPINDLE CELL TUMOUR
➢formerly know as spindle cell liposarcoma
➢Morphology: an ill-circumscribed, moderately atypical
spindle cell tumour featuring the presence of a variable
number of lipoblasts.
➢Matrix: vary, from fibrous to myxoid
➢Separation from well-diff liposarcoma/atypical
lipomatous tumour is due to the tumour is not driven
genetically by the amplification of MDM2 and/or CDK4
genes
➢There is no risk for future differentiation

11. ATYPICAL PLEOMORPHIC LIPOMATOUS TUMOURS
•presence of florette-like multinucleated giant cells
•presence of coarse eosinophilic collagen bundles
•higher cellularity
•increased mitotic activity
•numerous lipoblasts
➢Without reaching histology criteria consistent with
diagnosis pleomorphic liposarcoma
➢characterised by a benign clinical behaviour that
contrasts with the remarkable aggressiveness of
pleomorphic liposarcoma
➢Molecular study: RB1 gene loss
➢Prognosis : low rate of recurrence (0-15%) for
incomplete removal lesions

12. MYXOID PLEOMORPHIC LIPOSARCOMA
Epidemiology Children and adolescents with female
predominance
Site Mediastinum >> limbs >> head and neck region
Morphology features of both myxoid (presence of a rich
capillary size vascular network set in myxoid
background) and pleomorphic liposarcoma
(presence of pleomorphic lipoblasts.).
Pathogenesis No specific genetic aberrations
Clinical & Prognosis Clinical behaviour is aggressive (manifest as large,
deep-seated soft tissue mass)
High recurrence rate
early metastatic spread to the lungs, bone, and
soft tissues.

13. FIBROBLASTIC/ MYOFIBROBLASTIC TUMOURS

14. FIBROBLASTIC/ MYOFIBROBLASTIC TUMOURS

15. ANGIOFIBROMA OF SOFT TISSUE
TYPE benign neoplasm
Localization Typically arises in the extremities (mainly the legs)
frequently involving large joints (i.e. knee)
Epidemiology Predominantly middle-age, adult
Morphological Composed of a uniform spindle cell proliferation
set in a variably myxoid and collagenous
background, with a prominent vascular network
Stain express CD34 and EMA.
Sometimes Desmin positivity observed (in
dendritic cells)
Molecular
pathology
Presence of an AHRR-NCOA2 fusion gene
(majority cases)

16. EWSR1-SMAD3 POSITIVE FIBROBLASTIC TUMOUR
Definition Type: benign neoplasm
Localization Occur in the hands and feet
Epidemiology Broad age range
Morphological Composed of intersecting cellular
fascicles of cytologically monomorphic
spindle cells, alternating with
hypocellular, hyalinised areas
IHC nuclear expression of ERG

17. SUPERFICIAL CD34-POSITIVE FIBROBLASTIC TUMOUR
Definition Distinctive low grade neoplasm
Localization skin and subcutis of the lower extremities
Epidemiology middle-aged patients
Morphological composed of spindle and epithelioid cell
proliferation, often featuring striking
cytologic atypia that is associated with
insignificant mitotic activity
IHC invariably express CD34
Prognosis No recurrences are reported following
complete excision

18. SO-CALLED FIBROHISTIOCYTIC TUMOUR

19. SO-CALLED FIBROHISTIOCYTIC TUMOURS
➢Concept of fibrohistiocytic differentiation
➢In giant cell tumour, it contributes to the development of the lesion.
➢Malignant fibrous histiocytoma (MFH) - disappeared since 2013
➢MFH has accounted for approximately 50% of sarcoma diagnoses
(until early 2000)
➢ Undifferentiated pleomorphic sarcoma→Prototypical storiform
and pleomorphic variant MFH
➢ Giant cell MFH → (giant cell tumour of soft tissue, extraskeletal
osteosarcoma and giant cell rich osteosarcoma)
➢ Myxoid MFH →myxofibrosarcoma
➢ So called inflammation MFH→ inflammation variant of
dedifferentiated liposarcoma
➢ So called angiomatoid MFH → soft tissue lesion of unknown
origin

20. VASCULAR TUMOURS

21. VASCULAR TUMOURS
➢Very heterogenous in terms of degree of vasoformative morphology and
biological behaviour.
➢Epithelioid haemangioendothelioma (EHE) is ranked among vascular
malignancies, due to
➢metastatic rate of approximately 21%
➢aggressive in specific anatomic locations such as lungs and pleura.
➢Two recognised subtypes: by morphological and molecular variants
(CAMTA1 and TFE3-related)
➢However no statistically significant differences in terms of clinical behaviour

22. ANASTOMOSING HAEMANGIOMA
➢Single, benign vascular lesion
➢Frequently misinterpreted as angiosarcoma
➢ -endothelial atypia is mild
➢ -never associated with multilayering (angiosarcoma)
Localization • male genital tract
• most commonly in the kidney and in the
retroperitoneum of adults
Histopatology • composed of anastomosing capillary-sized
vessels featuring scattered hobnail
endothelial cells

23. PERICYTIC( PERIVASCULAR) TUMOURS

24. PERICYTIC (PERIVASCULAR) TUMOURS
➢ spectrum of perivascular neoplasia exhibiting a
variable contractile phenotype.
➢ Most lesion exhibit benign clinical course
➢ Update:
➢ The availability of STAT6 immunostaining →contributed to
improve diagnostic accuracy
➢ The prediction of the outcome of is not simply determined
by mitotic count→ but by a risk assessment of patient’s
age, tumour size, depth of location, and mitotic index
Glomus tumour

25. SMOOTH MUSCLE TUMOURS

26. EBV-ASSOCIATED SMOOTH MUSCLE TUMOURS
➢Associated with immunosuppression.
➢Age range is broad depends on anatomic location.
➢HIV-associated lesions tend to occur in the central nervous
system
➢Post-transplant proliferations feature a remarkable tropism for
the liver, followed by the lungs and the gastrointestinal tract.
➢Prognosis related to the state of immunosuppression
➢The changes introduced represented by inclusion as distinct
entitis of both
➢EBV-associated smooth muscle tumours
➢Inflammatory leiomyosarcoma
Histopathology of an EBV-associated leiomyosarcomas of the
gallbladder is composed of fascicles of mildly atypical spindle cells with
blunt-ended nuclei and eosinophilic cytoplasm (H&E stain)

27. INFLAMMATORY LEIOMYOSARCOMA
➢Occur in the deep soft tissues of the lower limbs, trunk
and retroperitoneum of adult patients
➢Peak incidence: third and the fourth decade
➢Microscopically smooth muscle cells are most often low
grade and associated with a lymphoplasmacytic infiltrates
➢less aggressively than ordinary leiomyosarcoma however
follow-up data are still very limited
The H&E (hematoxylin and eosin) stain demonstrates moderately
atypical spindle cells (white arrow) arranged in short fascicles with
admixed lymphocytes (yellow arrow) and xanthoma cells.