Renal tumors with different histological types occurring in the same kidney: A case report

Abstract

We report on one rare clinical case where renal tumors of different histological types occurred simultaneously. An 84-year-old male with two right renal tumors underwent radical nephrectomy. Pathology revealed chromophobe renal cell carcinoma (ChRCC) and clear cell renal cell carcinoma (ccRCC). He had a 3-year recurrence-free survival without renal function decline.

1 Introduction

Simultaneous renal tumors in the same kidney are rare and most commonly associated with hereditary syndromes, such as Von Hippel–Lindau disease and Birt–Hogg–Dubé syndrome. ^, However, reports of renal tumors with different histological types occurring simultaneously in the same kidney are extremely uncommon.

We herein report one case of synchronous renal tumors with distinct histological subtypes arising in the same kidney in patients without hereditary syndromes, along with a literature review.

2 Case presentation

Between January 2013 and December 2023, 327 patients underwent nephrectomy or partial nephrectomy for renal tumors at our hospital. Among these, 2 cases (0.6 %) involved synchronous renal tumors with different histological subtypes in the same kidney. One of the cases involved clear cell RCC (ccRCC) and angiomyolipoma (AML). The other case consisted of both renal tumors being malignant. Here, we provide a detailed description of this case.

An 84-year-old male with full activities of daily living (ADL) was referred to our hospital after plain computed tomography (CT) for a preoperative evaluation of spinal canal stenosis revealed a right renal tumor. Contrast-enhanced CT identified two distinct renal tumors in the right kidney with differing characteristics ( Fig. 1 ).

One tumor, located on the ventrolateral side, measured 20 × 19 mm and showed poor enhancement. Hypovascular renal cell carcinoma, such as chromophobe renal cell carcinoma (ChRCC) or papillary RCC, was suspected (cT1aN0M0, R.E.N.A.L. score 5a). The other tumor, located medially near the renal hilum, measured 21 × 20 mm, and exhibited an enhancement pattern suggestive of ccRCC (cT1aN0M0, R.E.N.A.L. score 8p).

Considering curative intent, retroperitoneoscopic right nephrectomy was performed without intraoperative or postoperative complications. A pathological examination revealed the following findings. The ventral tumor, on hematoxylin and eosin (HE) staining, exhibited a mixed pattern of large polygonal cells with abundant flocculent cytoplasm and small cells with eosinophilic cytoplasm. Immunohistochemical (IHC) staining was positive for CK7 and c-kit, consistent with a diagnosis of ChRCC (pT1a). The dorsal tumor, on HE staining, exhibited compact nests and sheets of cells with clear cytoplasm and distinct membranes. IHC staining was negative for CK7 and c-kit, consistent with a diagnosis of ccRCC (pT1a) ( Figs. 2 and 3 ).