Double Trouble: Renal Collision Tumors with Unexpected Histology-A Case Report with Review of Literature.

Primary Non-Hodgkin's Lymphoma (NHL) involving the adrenal gland is rare, and its synchronous occurrence with renal cell carcinoma (RCC) is exceedingly uncommon. Although adrenal involvement is observed in approximately 20% of systemic NHL cases, primary adrenal lymphoma accounts for only a small proportion of these cases. RCC accounts for 2-3% of all malignancies and is the second most common genitourinary cancer. The coexistence of RCC with other primary malignancies has been described, often in the context of familial syndromes; however, its synchronous presentation with primary adrenal NHL is exceptionally rare. A 54-year-old male with diabetes presented with intermittent dull left flank pain for 18 months and a recent loss of appetite. Contrast-enhanced computed tomography revealed a large, heterogeneous, hyper-enhancing mass in the left suprarenal region replacing the adrenal gland, along with a separate enhancing exophytic lesion in the left kidney. Positron emission tomography showed high metabolic activity in both lesions and regional lymph nodes. The patient underwent open radical nephrectomy with adrenalectomy and regional lymph node dissection. Histopathology demonstrated diffuse large B-cell lymphoma involving the adrenal gland with extension into the kidney, perinephric tissue, and perihilar fat, along with a separate Grade II clear cell RCC in the lower pole of the kidney. Immunohistochemistry confirmed B-cell lineage lymphoma. Lymph nodes were negative for metastasis. The patient received nine cycles of CHOP (Cyclophosphamide, Doxorubicin [Hydroxydaunorubicin], Vincristine [Oncovin], and Prednisolone) chemotherapy and remains recurrence-free at the 6-month follow-up. This case highlights a rare synchronous occurrence of primary adrenal NHL and ipsilateral clear cell RCC. Shared genetic or immunological mechanisms may underlie this association, warranting further investigation.