Recurrent and metastatic cutaneous neuroendocrine (Merkel cell) carcinoma mimicking angiosarcoma.

An elderly man presented with bright red-to-purple confluent nodules and plaques of the scalp that appeared clinically consistent with angiosarcoma. He had undergone surgical removal of a similar lesion from his left temple seven months before this presentation. Although routine histologic examination was not sufficient for diagnosis, Merkel cell carcinoma was diagnosed by immunohistochemical studies and electron microscopy. In addition, oat cell carcinoma of the lung was excluded with a computed tomographic scan of his chest. With chemotherapy, the recurrent and metastatic lesions of Merkel cell carcinoma completely resolved, rapidly recurred, and resolved a second time with chemotherapy. Eight months following the fourth course of chemotherapy, the patient again developed widespread cutaneous lesions. He committed suicide within one month of this last recurrence. An autopsy revealed no primary tumor other than of the skin.