Neuroblastoma like schwannoma: a diagnostic challenge

Description

A 21-year-old man presented with a subcutaneous swelling in the right forearm for 5 years, which was excised and subjected for histopathological examination. Grossly, it was an encapsulated globular tissue measuring 1.5x0.8x0.7 cm, with a greyish-white firm cut surface. Microscopically, it was composed of spindle-shaped cells having elongated nuclei with pointed ends, arranged in Antoni A and Antoni B patterns (figure 1). The central portion showed many large rosette like structures, composed of small round cells radially arranged around a central fibrocollagenous core (figure 2). These small cells were monomorphic, round to slightly elongated, with hyperchromatic nuclei and scant amount of cytoplasm, resembling lymphocytes. Masson's trichrome stain highlighted the central collagenous network (figure 3). Immunohistochemiscal results showed that these cells were strongly positive for S-100 with both cytoplasmic and nuclear staining (figure 4) and were negative for neuron-specific enolase, smooth muscle actin...

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