INTRANEURAL SCHWANNOMA. AN INCIDENTAL OBSERVATION. S. Squillaci C. Spairani R.Marchione F. Tallarigo* Servizio di Anatomia Patologica, Ospedale di Vallecamonica, Esine (Bs); *Servizio di Anatomia Patologica, Ospedale “S.Giovanni di Dio”, Crotone

This schema is reported in Rosai and Ackerman’s Surgical Pathology. Peripheral nerve tumors are neoplasms that includes benign (schwannomas, neurofibromas and perineuriomas) and malignant forms, collectively designated as malignant peripheral nerve sheath tumors (MPNST). Most schwannomas are uninodular, truly encapsulated, eccentric masses, dislocating the nerve fibers that can be demonstrated in the periphery, flattened along the capsule, but not penetrating the substance of the tumors.

CASE REPORT A 64-year-old man was referred to Hospital of Vallecamonica for excision of a 2 cm wide, nodular, formation on the left auricle. The lesion recurred 15 months later in the adjacent soft parts and a 3,6x1,5 cm. mass was removed with homolateral cervical lymph node clearance.

RESULTS Histopathology revealed a moderately-differentiated squamous cell carcinoma (G2) in the auricle and recurrent nodule without tumor invasion in 33 cervical lymph nodes. EE, 250X

SQUAMOUS CELL CARCINOMA EE 400X EE 250X

AN INCIDENTAL PATHOLOGICAL ASSOCIATION One of the cervical nerve showed a 6 mm. fusiform expansion of its structure. Microscopically the lesion was an encapsulated neoplasm growing inside the nerve. EE 100X

HISTOPATHOLOGICAL FINDINGS EE 40X EE 100X

Histopathological findings It was composed of short fascicles of bland spindle cells with focal nuclear palisading and Verocay bodies. EE 250X

IMMUNOHISTOCHEMISTRY The tumor cells expressed S-100 protein and were negative for EMA and GLUT-1 which stained instead the peripheral perineurial cells.

IMMUNOHISTOCHEMICAL FEATURES

CONCLUSIONS These findings were consistent with the diagnosis of intraneural schwannoma. The differential diagnosis includes traumatic and Morton’s neuromas, palisaded encapsulated neuroma, nerve sheath ganglion and intraneural perineurioma. In the present case, schwannoma was centrally located inside the nerve, a position that, to the best of our knowledge, has been reported in the literature only once.

REFERENCES 1) Fellegara G., Bisceglia M. Intraneural Schwannoma. Int.J.Surg.Pathol.2008;16:57-58