Bronchial carcinoid metastatic to skin. Light and electron microscopic findings.

This case report illustrates the value of ultrastructural examination of an undifferentiated carcinoma mestastatic to skin. In this patient, ultrastructural study of a cutaneous nodule demonstrated cytoplasmic neurosecretory granules characteristic of an amino precursor-uptake and decarboxylation cells (APUD) tumor and supported the diagnosis of metastatic bronchial carcinoid. Additional nine cases of bronchial carcinoids metastatic to skin are also briefly reviewed.