[The association of neuro-endocrine carcinoma of the skin and Bowen's disease. Review of the literature apropos of 4 cases].

Four cases of neuroendocrine carcinoma following Bowen's disease are presented. An immunohistochemical study was performed. The four patients, 3 men and a woman, ranging from seventy to eighty-seven years of age, developed a nodular tumor on a preexisting cutaneous lesion. In one of those cases the diagnosis of Bowen's disease was confirmed histologically before the apparition of the nodular tumor. The tumors were localized on the scalp, thorax, dorsum of the hand, and the scrotum. The four tumors were immunohistologically typical of neuro-endocrine carcinoma: there was a positivity for neurofilaments, cytokeratins and neurone-specific enolase. The clinico-pathological characteristics of those 4 neuro-endocrine carcinomas associated with a Bowen's disease, when compared with the 15 similar described in the literature, are identical to the isolated neuroendocrine carcinoma, from a clinical, morphological and evolutional point of view. The majority are seen in patients older than 60 years old and one third of the cases described survived at least 5 years. The coexistence of Bowen's disease and neuroendocrine carcinoma, the association of neuroendocrine and epidermoid cells in other cutaneous tumors, reactivate the controversy concerning the histogenesis of the so-called Merkel cell carcinoma. In fact, the histogenesis of the tumor is still not fully understood.