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Schwannoma - pelvic

Case contributed by Dr Frank Gaillard
Modality: MRI

Case Discussion:

Final Diagnosis:

Pelvic tumor, resection: Schwannoma.

Macroscopic appearance

Specimen is received fresh in a plastic bag labelled with the patient's demographics and B -PELVIC TUMOUR -RETROPERITONEAL. It consists of a large number of variably sized, firm, tan-grey and hemorrhagic tissue fragments with aggregate measurements of 13 x 8 x 2.2 cm. The largest piece measures 4 x 2.5 x 0.9 cm. The sectioned surfaces of the larger pieces are solid and variegated with tan and yellow areas in additional to well-circumscribed, shiny white foci of probable calcific areas. Other fragments show a muscular tissue appearance on sectioned surfaces as well as on the outer surface. In other fragments, the cut surfaces are more soft and gelatinous.


Representative sections show characteristic features of Schwannoma. The tumor is composed mostly of hypercellular (Antoni A) areas with some alternating hypocellular (Antoni B) areas. There are subtle Verocay bodies. At low power, there is marked nodularity to this Schwannoma. Areas of hyalinization as well as hyalinized blood vessels are seen. Clusters of reactive lymphocytes are seen. The areas between the nodules of this Schwannoma are made of dense connective tissue. There are no atypical features such as mitotic activity, necrosis, or marked pleomorphism. The tumor cells are immunoreactive for S-100. Neurofilament immunostaining shows scattered nerve twigs between the tumor nodules and occasionally within the tumor. Overall, this tumor represents benign Schwannoma.

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