Distal Phalangeal Metastasis of Extramammary Paget's Disease

A rare case of phalangeal metastasis of extramammary Paget's disease in a 68‐year‐old man is described. The patient developed an erythematous, slightly elevated area in the pubic region. A biopsy specimen demonstrated numerous, large, rounded cells with ample pale‐staining cytoplasm proliferating in the epidermis. With a diagnosis of ***extra‐mammary Paget's disease, he underwent wide local excision and inguinal node dissection. Eleven months postoperatively, the patient developed a tender, red, swollen right ring finger. Bone X‐ray showed that the distal phalanx of the ring finger had completely dissolved. Histopathological examination demonstrated proliferation of tumor cells in the adipose tissue. They had poorer and darker cytoplasm than the Paget's cells in the epidermis of the pubic region. Immunohistochemically, these cells showed the same staining pattern as did the Paget's cells at the primary site. Accordingly, the patient was diagnosed with distal phalangeal metastasis of extramammary Paget's disease. Two weeks after the appearance of the distal phalangeal metastasis, the patient died of cancerous pleurisy. It has been reported that patients with phalangeal metastasis have a very poor prognosis.