Collision Kidney Tumor Consisting of Clear Cell Renal Cell Carcinoma and Primary Renal Mantle Cell Lymphoma: A Case Report.

ABSTRACT

BACKGROUND: Non-Hodgkin's lymphoma (NHL) seldom involves the kidney, and it is even more uncommon for the kidney to be the primary renal non-Hodgkin's lymphoma (PRNHL). Due to its rarity, PRNHL is often confused with renal cell carcinoma (RCC). Tumor collision refers to the simultaneous development of two histologically distinct malignancies in the same organ or space. Collision kidney tumors have already been described but only in a few cases. Here, we report an extremely unusual case involving a collision tumor between PRNHL and RCC. CASE PRESENTATION During a routine physical examination, a 61-year-old male was diagnosed with a tumor in his left kidney. The patient underwent a laparoscopic left partial nephrectomy. A 3.2 cm renal mass was seen on gross examination of the nephrectomy specimen, and the final pathology showed two different tumor types. The first type was a typical clear cell renal cell carcinoma (ccRCC), which made up the majority of the overall tumor. The second was composed of small- to medium-sized lymphoid monomorphic cells with uneven nuclei. Immunohistochemistry confirmed the diagnosis of a collision tumor consisting of PRNHC and ccRCC. After surgery, the patient received five courses of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) therapy. With the gradual deterioration of all aspects of his physical function, the patient finally died of respiratory failure 15 months later. CONCLUSIONS: We present a rare case of a collision tumor consisting of renal cell carcinoma and primary renal non-Hodgkin's lymphoma. Despite their rarity, it is essential to report such cases to further understand the behavior of these tumors and develop evidence-based treatment strategies.