Primary renal inflammatory myofibroblastic tumor.

A case of primary renal inflammatory myofibroblastic tumor of the left kidney in a 51-year-old man clinically presenting bleeding from the gums with thrombocytopenia and left flank mass is reported. Pathological examination of the left renal tumor characterizes macroscopically by a cortical mass and histologically by spindle cells admixed with variable amounts of extracellular collagen, lymphocytes and plasma cells. Immunohistological stainings are positive vimentin and focal positive smooth muscle actin. Clinical and pathological features with a brief review of the relevant literature are discussed. This is the first reported description in the literature of primary renal inflammatory myofibroblastic tumor associated with thrombocytopenia.