第1趾基節骨に発生したprimitive neuroectodermal tumorの1例

Primitive Neuroectodermal Tumor of the Proximal Phalanx of the First Toe. Case Report

　第1趾基節骨に発生したPNET（primitive neuroectodermal tumor）の1例を経験したので報告する．症例は21歳の男性で，右第1趾の疼痛を認め，単純X線像で第1趾基節骨に菲薄化を伴う骨透亮像を認めた．良性腫瘍を考え，掻爬・骨移植を行ったが，病理結果はPNETであり，放射線・化学療法を施行した．追加手術は行わず経過観察を行い，15年間再発・転移は認めない．PNETは一般に予後不良であるが，本例は足趾の発生で，化学療法が有効であったことなどが良好な経過が得られた要因と考えられた．

　We report a rare case of primitive neuroectodermal tumor (PNET) arising from the proximal phalanx of the first toe. A 21-year-old man presented with pain in the right first toe after minor trauma. A roentgenogram showed a radiolucent expansive lesion and thinning in the proximal phalanx of the right first toe. A benign tumor was suspected, and curettage followed by bone grafting was performed. The histological diagnosis, however, was PNET with a low mitotic index, and radiotherapy and chemotherapy were performed immediately. Additional wide excision was not performed. The patient has had no evidence of recurrence or metastasis during the 15 years since surgery. The prognosis of PNET is generally poor, but our patient is a long-term survivor. We think that the small tumor volume, low-grade malignancy, and good response to chemotherapy were factors that led to his long-term survival.