Renal cell carcinoma with intravascular lymphomatosis: a case report of unusual collision tumors with review of the literature.

We report the case of a 77-year-old white woman who presented with a left breast mass, lethargy, and weight loss. Pelvic computed tomographic scan revealed a 9.5-cm mass in the right kidney. Surgical pathology demonstrated a diffuse large B-cell lymphoma of the subcutaneous tissue of the breast and renal cell carcinoma with concurrent extensive intravascular lymphomatosis. Systemic dissemination of malignant lymphoma to a concurrent visceral primary neoplasm is rare. To the best of our knowledge, this is the first case illustrating a renal cell carcinoma collision with intravascular lymphomatosis.