Infiltrating glomus tumor of uncertain malignant potential arising in the kidney.

Glomus tumors closely resemble the normal glomus body and have a predilection for skin and subcutaneous tissue. These tumors rarely present in visceral organs. We report a case involving the kidney. This glomus tumor displays typical cytology and immunohistochemical profile of glomus tumors elsewhere. However, this tumor is large, has a deep location and exhibits an infiltrative margin and increased mitotic activity. These features, by current definition, would suggest malignant behavior. However, the rarity of such an entity in the kidney highlights the need for caution and a diagnosis in a continuum between benignity and malignancy. To the best of our knowledge, this report is the first case of infiltrating glomus tumor or glomus tumor of uncertain malignant potential arising in the kidney.