Trichoblastic carcinosarcoma is a seldom biphasic adnexal tumor with malignant epithelial and mesenchymal components. The authors report the first tumor on the neck developed from preexistent trichoblastoma showing aggressive, recurrent behavior. An 82-year-old man presented with a solitary 3-cm exophytic lesion. Histology verified the diagnosis of trichoblastic carcinosarcoma. Four years earlier, a trichoblastic carcinoma arising in a preexisting trichoblastoma was excised at the same location. Despite successful surgical treatments, three local recurrences within 4 years were diagnosed. After the second relapse, the patient agreed on adjuvant radiation. Twelve months later, another relapse was excised in toto. In the last surgical specimen, only the mesenchymal component was found. Copy number variation analysis of the preexisting tumor and two recurrences revealed the same entity and additional chromosomal aberrations in the recurrences. Adnexal carcinosarcomas are seldom, yet presumably underdiagnosed biphasic tumors with aggressive growth potential. They should have adequate preoperative clarification with wide tumor excision, as radiosensitivity seems to be of limited effect.
Keywords: biphasic tumor; cutaneous carcinosarcoma; trichoblastic carcinosarcoma; trichoblastoma.
© 2023 The Authors. The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.