Primary nodal neuroendocrine (Merkel cell) tumor in a patient with HIV infection.

Lymphadenopathy in the human immunodeficiency virus (HIV) can be of diverse etiology, ranging from infection to cancer. A neoplasm of epithelial origin manifested as inguinal lymphadenopathy without a primary lesion is rare. We report a case of Merkel cell tumor confined only to a lymph node in a patient with the acquired immunodeficiency syndrome (AIDS). We believe this is the first report of primary nodal Merkel cell tumor in a patient with HIV. Because Merkel cell tumor is a rare skin neoplasm with features suggestive of high malignant potential, it is important to distinguish a primary nodal Merkel cell tumor from malignant metastatic processes on the one hand and relatively benign causes of adenopathy on the other.