Case 116

A 54-year-old male with a soft tissue chest mass.

1. What's the diagnosis:

   A: Neurofibroma

   B: Desmoid

   C: Schwannoma

   D: Hybrid nerve sheath tumor (neurofibroma/schwannoma)

Answer

The correct answer is D. Biopsy shows a benign peripheral nerve sheath tumor with nodular proliferation of elongated spindle cells with verocay bodies, showing schwannoma histology, and areas of neurofibroma-like appearance, demonstrating mixed population of cells with loose myxoid stroma, and "shredded-carrots" collagen fibers. Tumor cells are strongly and diffusely positive for S-100 and Neurofilament stain highlights rare axons. This tumor shows features of schwannoma and neufibroma; thus, we designate it as a "hybrid nerve sheath tumor (neurofibroma/schwannoma)".

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD