Skin metastasis of neuroendocrine carcinoma derived from the mediastinum.

We report a 46-year-old Japanese man with a metastatic skin tumor on his left palmar region. He underwent resection for a mediastinal neuroendocrine carcinoma in February of 1998. After the operation, he immediately noticed an elevated tumor on his left palm. In September 1999, a brain tumor was discovered. The skin and brain tumors were subsequently removed surgically. Neuron specific enolase (NSE) in the serum was elevated to 25 ng/ml. A skin biopsy specimen from the left palmar site revealed multiple tumor nests which showed the same histological features as the primary mediastinal tumor. Immunostaining was positive for chromogranin, synaptophysin, and NSE but negative for S-100 protein and CD57. To our knowledge, this is the first report of cutaneous metastasis of a neuroendocrine tumor derived from the mediastinum.