This document discusses radiological imaging findings of gastrointestinal schwannomas. Some key points: - Gastrointestinal schwannomas most commonly occur in the stomach (60-70% of cases). On CT and MRI, they often appear as well-defined, hypodense masses that demonstrate homogeneous enhancement with contrast. - While radiological imaging findings are nonspecific, gastrointestinal schwannomas typically have the appearance of a solitary mass, and immunohistochemical staining can aid in diagnosis. - Schwannomas can also occur in rare locations like the pancreas, adrenal gland, retroperitoneum, abdominal wall, pelvis and liver. Imaging characteristics vary depending on the location but may include cystic degeneration

1. Radiological Imaging of Gastrointestinal tract Schwannoma.
Dr/ ABD ALLAH NAZEER.MD.

2. Schwannoma represents 1% of tumors of the
gastrointestinal tract and parts 2-8%
mesenchymal tumors of the gastrointestinal. In
patients with neurofibromatosis type 1 there
gastrointestinal involvement in 10-25% of cases
including: neurofibroma solitary leiomyoma and
rarely plexiform neurofibroma.
More and more frequently diagnosed by
immunohistochemical stains.
The average lesion size is 6-7 cm (range, 0.5 to 14
cm). They occur most often in the stomach (60-70%
of cases), followed by colorectal, being exceptional
in the small intestine and esophagus

3. Gastric
Represent 0.2% of gastric tumors, 4% of all benign gastric tumors
with peak incidence between the fourth and fifth decade of life. It is
usually asymptomatic, with incidental finding, although they are
sometimes shaped symptomatic gastrointestinal ulceration and
bleeding.
Gastrointestinal schwannomas are distinctly different neoplasms
from conventional soft-tissue and central nervous system
schwannomas, some of which may be associated with
neurofibromatosis 2.
Most injuries TC are hypodense, well defined and standardized with
homogeneous enhancement contrast, endoscopy can be checked
exophytic nature of the injury. For RM, most of the lesions are
iso/ hypointense on T1-weighted sequences and hyperintense on
T2-weighted sequences. The discrepancy in signal intensity between
our T2-weight-ed images and those described in literature might be
caused by the presence of melanin in the schwannoma.

4. A 41-year-old female with a Schwannoma of the stomach. A. Unenhanced CT
shows a well-defined extraluminal soft tissue mass with homogeneous density;
B. Enhanced CT shows the neoplasm is of homogeneous enhancement.

5. Schwannoma, Large exophytic soft
tissue mass arising from the
greater curvature of the stomach.

6. Abdominopelvic computed tomography scans show a 1.5×1.0 cm sized
homogenously-enhancing mass in the anterior wall of the duodenal
bulb (arrow). (A) Axial section view. (B) Coronal section view.

7. Schwannoma of the stomach.

8. Pancreatic schwannoma is extremely rare with similar incidence in both
genders. Pancreatic schwannoma is a slowly growing, encapsulated, benign
neoplasm that typically arises in the peripheral epineurium of either the
sympathetic or parasympathetic autonomic fibers or branches of vagus
nerve that extend to the pancreas. Pancreatic schwannomas most
frequently involve the pancreas head (40%), followed by body (21%), neck
(6%), tail (15%), and uncinate process (13%), respectively. Patients with
pancreatic schwannoma are usually asymptomatic, or have abdominal
pain, nausea, and vomiting. Weight loss and jaundice may sometimes be
seen. CT or MRI can help distinguish if a lesion is solid or cystic, can define
the anatomic location of the lesion, delineate its relation to mesenteric
vessels, and determine the lesion causes pancreatic duct dilation. The
features of pancreatic schwannomas on CT scan include low-density
and/or cystic degenerative areas. MR imaging usually shows hypointensity
on T1-weighted images and hyperintensity on T2-weighted images but
like the CT features, these findings are nonspecific. Two-thirds of
pancreatic schwannomas undergo degenerative changes such as cyst
formation, necrosis, calcification, and hemorrhage, and these changes
can mimic pancreatic cystic tumors.

9. 60-year-old male with pancreatic schwannoma. A, B There is heterogeneously enhancing
mass (arrows) in the pancreas uncinated process on arterial axial (A) and venous phase
coronal (D) images. C, D On pathology, the mass showed cystic degeneration with
hemorrhage (C H&E stain ×4) and was positive for S100 on immunohistostain (×10).

10. 40-year-old female with pancreatic schwannoma. A On venous phase axial
CT, there is a round low-density cystic mass (arrow) in the pancreas neck. B
On MRI axial T2WI, the cystic mass (arrow) shows small septations. C On
post-contrast axial image of MRI, there is mild septal enhancement (arrow).

11. Pancreatic schwannoma.

12. Well-defined cystic lesion located in the retroperitoneal space under the cauda pancreatis
slightly pushing it back and the adjacent jejunal loops. Distinct liquid T2 hypersignal of the
tumour. a: injected CT-scan, coronal format; b: injected CT-scan, axial section; c: MRI in T2
weighting, axial plane.

13. Pancreatic schwannoma
showing increased FDG
uptake on PET/CT.

14. 60-year-old female with peripancreatic schwannoma. A–C There is a well-circumscribed
low-density solid mass (arrows) in the region of pancreas head/neck with central cystic
degeneration/necrosis on arterial phase (A) and venous phase (B, C). Note vascularity in
the solid portion of the mass seen inferiorly and mild upstream pancreatic duct dilation (C).

15. Schwannomas that arise in the adrenal medulla are very rare. Often,
schwannomas of the retroperitoneum, especially in the juxta-adrenal
space, can be misdiagnosed as they can mimic more common primary
adrenal lesions. Studies have shown that approximately 0.5% to 5% of
schwannomas are retroperitoneal, constituting <0.2% of adrenal
incidental tumors. Most of the patients do not have any symptoms and
delayed diagnosis results in a significant size at the time of diagnosis.
Both CT and MRI are nonspecific in diagnosis of adrenal schwannomas.
Adrenal schwannomas often show septa and cystic change. Cystic changes
are rare in other retroperitoneal tumors. Characteristic enhancement
patterns of primary adrenal schwannomas are mild heterogeneous
enhancement on arterial phase and progressive enhancement during the
portal venous and equilibrium phases, which are likely due to variable
degree of tumor cellularity or degenerative changes such as cystic
degeneration, necrosis, and hemorrhage. Minimal contrast enhancement
may be seen in neoplasms with low cellularity and edema. On MRI,
schwannomas exhibit low-signal intensity on T1-weighted images and
heterogeneous high-signal intensity on T2-weighted images

16. 50-year-old female with
retroperitoneal/adrenal
schwannoma. The mass
(arrows) shows low-
signal intensity on T1WI
(A), high-signal intensity
on T2WI (B, C), with
cystic component,
multiple internal septa,
and surrounding
capsule. After contrast
enhancement (D, E), the
mass (arrows) shows
peripheral enhancing
solid component.

17. A giant spinal schwannoma mimicking a renal mass.

18. 70-year-old male with small bowel schwannoma. A, B There is an incidentally found
homogeneously enhancing mass (arrows) in the ileal loop on venous phase CT (A) and
contrast-enhanced MR (B). C FDG uptake is seen on fusion image of PET/CT. D, E On
pathology, the neoplasm (arrow) abuts the jejunal wall on H&E stain (D ×4). The neoplasm
involved the submucosa and muscularis propria. The mass was composed of a bland
spindle cell proliferation with a prominent lymphoid cuff. Neoplastic cells are diffusely
positive for S-100 protein (E ×20). The mass was negative for c-Kit, DOG1, and SMA

19. Abdominal CT and MRI findings
of the patient. a Plain CT scan
revealed a 4.0 × 3.2 × 3.0-cm
hypodense mass in the porta
hepatis (black arrow). b Enhanced
CT scan revealed a mildly
enhanced mass in arterial phase
(black arrow). c Moderately
enhanced mass in portal phase
(black arrow). d MRI revealed a
4.0 × 3.0-cm mass in the sagittal
section (black arrow). e Low signal
intensity in T1-weighted imaging
(black arrow). f High signal
intensity in T2-weighted imaging
(black arrow).

20. Multiple
schwannomas
synchronously
occurring in
the porta
hepatis, liver,
and
gallbladder:

21. Incidental finding in patients with a history of splenectomy. in hilum loculated liver, hypodense, cystic
appearance without mass effect or biliary dilatation associated injury. Schwannoma hepatic hilum.

22. Retroperitoneal schwannoma.

23. Schwannoma, well-defined, retroperitoneal soft tissue mass in close proximity to
the superior mesenteric vessels with a feeding vessel from the superior mesenteric
artery (SMA) and venous drainage to the superior mesenteric vein (SMV).

24. CT injected at portal time revealing this mass along the retroperitoneal vessels and the
independent and slightly retaining aspect of the intestinal loops. Presence of a
central necrosis and several microcalcifications. a: oblique coronal format; b: axial section.

25. Retroperitoneal schwannoma.

26. Giant retroperitoneal
ancient schwannoma

27. Giant ossified
benign
mesenteric
schwannoma

28. Abdominal wall Schwannoma.
(a) Color flow showing
hypovascularity of the mass.
(b) B-mode ultrasound shows
the well-encapsulated mass in
anterior abdominal wall (arrow).

29. Abdominal Wall
Schwannoma

30. MRI and CT analysis confirmed the
retroperitoneal Schwannoma.

31. PET (first line), CT (second line) images and PET-scan fusion (third line)
objectifying the fixation of 18-FDG within the tissue zones of the mass.

32. Pelvic MRI revealing the tumour in distinct T2 hypersignal (a) enhanced
after injection (b), the lesion appearing well defined developed at the
expense of the right L5 root. a: coronal section in T2 weighting; b: axial
section in T1 fat-sat weighting after injection of gadolinium.

33. Retrorectal tumor: a case report of a patient with "schwannoma.

34. Ancient schwannoma. (a) Axial T2-weighted MR image shows a well-defined, complex
cystic lesion with internal septa and solid components (arrow) in the left hemipelvis. (b)
Axial postcontrast T1-weighted MR image reveals heterogeneous enhancement
of the internal septa and solid components (arrow). Surgical excision and
histopathologic analysis helped confirm the diagnosis of ancient schwannoma.

36. Pelvic schwannoma, Fat-suppressed T2-weighted coronal (A), sagittal (B),
axial (C) postoperative tumor image. There was remained tumor and
capsule on magnetic resonance image in the post-operative 7 months.

37. Pelvic schwannoma. (a) Axial T2W fat-suppressed and (b) post-contrast
fat-suppressed T1W images show a heterogeneously hyperintense area in
T2W image due to microcytic spaces (arrowheads). Peripheral contrast
enhancement is observed in post-contrast T1W image (curved arrows).

38. Rectal schwannoma in 67-year-old woman. Sagittal T2-weighted
image (A) and axial T1-weighted image (B) show well-circumscribed
homogeneous submucosal mass (arrows) in lower rectum.

39. Malignant
Schwannoma
of Anterior
Abdominal Wall

40. Thank You.