Glomus tumor of the kidney: case report and literature review.

Glomus tumor is a benign mesenchymal neoplasm of the subcutaneous tissue of the distal extremities and head and neck region. Glomus tumor rarely occurs in the visceral organs. This study reports the sixth case of a glomus tumor arising in the kidney in a 62-year-old man who presented with weight loss and an incidental kidney lesion detected by computed tomographic scan. Radiologically, the tumor was difficult to differentiate from a malignant lesion and was therefore excised by partial nephrectomy. The tumor was challenging to diagnose by routine hematoxylin and eosin microscopic examination, necessitating immunohistochemical analysis. Immunoreactivity was demonstrated for smooth muscle actin, vimentin, collagen IV, and CD57, with little to no expression of neuroendocrine, endothelial, or epithelial markers. To date, the tumor has followed a benign course without evidence of local recurrence or metastasis.