Multinodular cutaneous spread in neuroendocrine tumor of the breast : an unusual presentation.

Carcinoid tumors are the most common type of neuroendocrine tumors with an incidence of 1.5 per 100 000 of the population. Skin manifestations of carcinoid tumors include those associated with the carcinoid syndrome and sequelae from metastatic disease. Carcinoid tumors in the breast, which were first described in 1977, are rare and may present either as primary or metastatic lesions. The existence of primary breast carcinoid tumors is controversial, however, and, if they do exist, would account for <1% of primary breast cancers. We report the case of a 76-year-old woman who presented to the M.D. Anderson Cancer Center with a long-standing history of a breast lump. Core biopsy of the mass and left axillary lymph node aspiration revealed neuroendocrine tumor of the breast, which stained positive for synaptophysin and chromogranin. Subsequently, the patient developed a left-sided pleural effusion, and a further work-up revealed metastases to the lung parenchyma and pleural space. Three years after her diagnosis, she complained of a persistent, erythematous thickening of skin over the surface of her left inferior breast, which had been present for 1 year. On examination, multiple erythematous grouped nodules arranged in an oval pattern were present. A punch biopsy from one of the nodules revealed invasive low-grade carcinoma with neuroendocrine features similar to those in her prior breast core biopsy. The tumor was seen to be infiltrating the dermis. This is a unique case of a neuroendocrine tumor of the breast with cutaneous spread. The number of reported cases of neuroendocrine tumors with cutaneous involvement remains small.