ゆうぜい状表皮発育異常症患者に生じたＭｅｒｋｅｌ細胞癌の１例

Abstract

We reported a case of epidermodysplasia verruciformis (EV) in which Merkel cell carcinoma developed. When he was 51 years old, he had received post-operative radiotherapy for squamous cell carcinoma on his occipital scalp. The patient was a 63-year-old Japanese man with a six-month history of eroded lesion on his temporal scalp. Physical examination revealed 20×20mm well-circumscribed, eroded lesion of the left temporal scalp. Multiple erythematous or brown scaling macules and plaques (1 to 3 cm) were scattered over his trunk. There was no superficial lymphadenopathy. Histopathologically, the specimen from the temporal lesion demonstrated proliferation of small, round and basophilic atypical cells from superficial to lower dermis. The overlying epidermis was necrotic. In the remaining epidermis around the tumor, atypical cells with hyperchromatic nuclei were observed. Immunohistochemically, the basophilic cells proliferating in the dermis expressed low-molecular-weight cytokeratin (CAM5.2), epithelial membrane antigen, neuron-specific enolase and chromoglanin A, but not leukocyte-common antigen, S-100 protein, vimentin or involucrin. Atypical cells in the neighbouring epidermis were positive for CAM5.2. Electron microscopically, the tumor cells in the dermis contained dense core granules in the cytoplasms. Although several types of skin tumor often developed on sun-exposed area of EV patients, development of Merkel cell carcinomas has been rarely reported. Preceding X-ray therapy might be related to the development of Merkel cell carcinoma in the present case.