Primary mucinous carcinoma of skin: histochemistry and electron microscopy.

Two primary mucinous carcinomas of skin were studied by histochemistry and by light and electron microscopy. Enzyme histochemistry showed a pattern of reactivity similar to that found in eccrine secretory epithelium. Mucin histochemistry substantiated previous reports of probable sialomucin formation. Electron microscopy revealed a highly differentiated neoplasm with a mode of mucin secretion similar to that observed in the dark (mucinous) cell of the eccrine coil. The natural history of mucinous carcinoma of skin indicates that although local growth is the rule, lymph node metastasis may occur.