[Cutaneous neuroendocrine carcinoma : apropos of a case]

A case of neuroendocrine carcinoma (Merkel cell tumor) of the skin in a 76 years old woman is reported. The lesion, an erythematous nodule, 2 to 3 cm in diameter occurred on the face. Light microscopic examination showed sheets of indifferentiated cells that had a uniform round nucleus and scanty cytoplasm containing argyrophil granules. An ultrastructural study demonstrated neurosecretory type granules in the cytoplasm of the tumor cells. Immunocytochemical analysis was strongly positive for neuron specific enolase, but negative for Met-Enkephalin. This case is discussed in the light of a review of 73 cases already published in the literature. The origin of the cells involved in this tumor is still discussed. Several authors have suggested that this tumor is an Apudoma possibly arising from Merkel cells. In most cases, the lesion is an erythematous nodule. The most common localization is the face (45 p. 100). The tumor can be diagnosed by routine histology, but silver staining and electron microscopic study are often helpful. Removal of the tumor should be performed. This tumor appears to be of a low grade malignancy. Local recurrences or metastases have been reported in a few cases.