Hybrid schwannoma/perineurioma: a report of two cases including a possible radiation-induced case.

Hybrid schwannoma/perineurioma represents a recently characterized dermal or subdermal tumor showing schwannian cytomorphology and a perineurioma-like architecture composed of an admixture of both cell types. We report two additional cases of hybrid schwannoma/ perineurioma, one of which occurred after irradiation. Patient 1 was that of a 33-year-old man presented with a 2.8-cm dermal tumor on his left lower leg. Patient 2 was that of an 89-year-old woman with a history of uterine carcinoma treated by surgery and radiation therapy at the age of 35. She presented with a 1.2 × 1.0 cm dermal tumor on her left mons pubis with multiple coincidental basal-cell carcinomas around it. Both tumors were microscopically well circumscribed but unencapsulated and situated in the dermis and adipose tissue and showed a vague storiform and lamellar pattern. Cytologically, both tumors contained two-cell populations, i.e. spindled cells with plump nuclei, which were positive for S-100 protein and negative for epithelial membrane antigen (EMA), claudin-1 and CD34, as well as cells with very slender nuclei and elongated cytoplasmic processes, which were negative for S-100 protein yet expressed EMA, claudin-1 and CD34. Claudin-1 was a better marker to highlight cells with very slender nuclei than EMA. Both tumors lacked expression of neurofilament.

Ohata C ，Imai N ，Hinogami H ，Akamatsu K ，Sumimura Y ... -  《-》

Hybrid schwannoma/perineurioma: clinicopathologic analysis of 42 distinctive benign nerve sheath tumors.

Hornick JL ，Bundock EA ，Fletcher CD 《-》

Hybrid schwannoma/perineurioma: report of 10 Chinese cases supporting a distinctive entity.

Yang X ，Zeng Y ，Wang J 《-》

Congenital melanocytic nevus with features of hybrid schwannoma/perineurioma.

Neural differentiation by melanocytic nevi represents a well-recognized phenomenon, and melanocytic nevi with perineurial differentiation have been reported recently. We reported a case of a congenital melanocytic nevus with histopathologic features of hybrid schwannoma/perineurioma. The patient was a 36-year-old male who presented with a black tumor on his arm since birth. Histopathology showed a congenital melanocytic nevus in the superficial dermis, but more strikingly, in continuity with the melanocytic nevus, there was a well-circumscribed but unencapsulated nodule in the deep dermis. The nodule was composed of cellular and myxoid areas with storiform, laminated or whorled growth patterns. The cellular area was mainly composed of proliferation of plump spindle, oval or epithelioid cells. The myxoid area was mainly composed of proliferation of slender spindle cells with mucin deposition. Immunohistochemical stains showed that the cellular area was positive for S100 and CD34, weakly positive for EMA, negative for Glut-1 and collagen IV, the myxoid area was positive for S100, negative for CD34, strongly positive for EMA and focally positive for Glut-1 and collagen IV. Our results show that congenital melanocytic nevi may show neural differentiation with histopathologic features of hybrid schwannoma/perineurioma.

Wang L ，Wang G ，Gao T 《-》

[Hybrid schwannoma/perineurioma: a clinicopathological analysis of 35 cases].

Jiang XB ，Zhang L ，Sun M ，Zhao L ，Lao QY ，Yu L ，Wang J ... -  《-》