Peripheral nerve sheath tumor of uncertain malignant potential

Case contributed by A.Prof Frank Gaillard

Presentation

Chest pain.

Patient Data

Age: 35 Years
Gender: Male

A large right posterior mass protruding into the pleural space is associated with adjacent atelectasis and small pleural effusion.  There is no clear extension into neural exit foramina and no bony remodelling is seen. Lungs and pleural spaces are otherwise clear. No mediastinal, hilar or axillary lymphadenopathy.

A large paraspinal mass with intermediate T1 and relatively high, but heterogeneous, T2 signal is noted. No extension into the spinal canal. 

MACROSCOPIC APPEARANCE: A 105x85x80mm oval partly lobulated yellow solid lesion with two thirds smooth surface and one third irregular surface received fresh. The specimen 369g. The specimen is serially sectioned to reveal a tan soft to fleshy cut surface with relatively uniform soft to fleshy cut surface. 

MICROSCOPIC DESCRIPTION:  The sections show a variably hypercellular spindle cell tumor. Tumor cells have moderately pleomorphic vermiform nuclei with coarse bipolar processes and are dispersed within a fibrous and myxoid stroma. Scattered mitotic figures are identified (6 in 40 HPF). No areas of necrosis are seen. Scattered collections of small lymphocytes are noted. The tumor is partially enclosed within a fibrous capsule of varying thickness. No breach of the capsule is seen. 

Immunohistochemistry shows strong staining in tumor cells for S-100 protein and variable moderate staining for neurofilament protein (NFP). The topoisomerase labeling index shows a wide variation but is up to 40% in more hypercellular areas.

FINAL DIAGNOSIS: Peripheral nerve sheath tumor of uncertain malignant potential. 

Case Discussion

This case, which was histologically shown to be of a  peripheral nerve sheath tumor of uncertain malignant potential, demonstrates that absence of extension into the neural exit foramen does not mean neurogenic tumors should be excluded. 

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Case information

rID: 42660
Published: 16th Apr 2016
Last edited: 16th Mar 2019
Inclusion in quiz mode: Included

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