A Collision Tumor of Papillary Renal Cell Carcinoma and Oncocytoma

Case Report and Literature Review

Rajen Goyal, MD; Anil V. Parwani, MD, PhD; Lan Gellert, MD, PhD; Omar Hameed, MD; Giovanna A. Giannico, MD

Disclosures

Am J Clin Pathol. 2015;144(5):811-816. 

In This Article

Abstract and Introduction

Abstract

Objectives: The most common renal neoplasms include clear cell, chromophobe, and papillary renal cell carcinomas (PRCCs) and oncocytomas. While lesions containing hybrid features of different tumor types, such as hybrid oncocytic tumors, have been well documented in the literature, the finding of a collision tumor of two distinct tumor types—PRCC and oncocytoma—is extremely rare.

Methods: We present a case of PRCC associated with an oncocytoma. Our discussion includes a review of the available literature on this rare type of collision tumor.

Results: Prosection of a partial nephrectomy performed in a 78-year-old man for painless gross hematuria and nocturia revealed a 6.4 × 5 × 3.6-cm well-delineated orange to yellow-tan mass harboring a white-tan 1 × 0.9 × 0.9-cm mass. Histologic diagnosis of PRCC associated with an oncocytoma was rendered. By immunohistochemistry, focal CK7 expression was present in the oncocytoma, while strong diffuse positive CK7 expression was present in the PRCC component. Fluorescence in situ hybridization (FISH) revealed trisomy 17 in 39.3% of PRCC tumor nuclei but no significant chromosomal aberration in oncocytoma.

Conclusions: In view of this and previously reported cases, thorough sectioning and examination, especially in large oncocytomas, is recommended to exclude the presence of an associated malignancy. To our knowledge, trisomy 17 by FISH has not been previously reported in these extremely rare tumors.

Introduction

Despite the emergence of several recently recognized entities within the World Health Organization classification of renal tumors, papillary renal cell carcinoma (PRCC) and oncocytoma are among the most well-understood and common renal tumors.[1]

PRCC is the second most common subtype of renal cell carcinoma (RCC), comprising 11% to 18.5% of all RCCs. It occurs across a broad age range, from 30 to 80 years, and is more commonly associated with multifocality compared with other malignant renal tumor subtypes.[2–10] PRCC is subdivided into types 1 and 2, with type 1 having a better overall survival.[11] PRCC commonly shows trisomy or gains of chromosomes 7 and 17 and loss of chromosome Y.[12–15] However, anomalies in chromosomes 1, 5, 6, 8, 11, 15, 18, and 22 are more frequently associated with type 2 PRCC.[16–18] Immunohistochemical studies helpful in the diagnosis of this tumor include cytokeratin 7 (CK7; diffusely positive in the majority of type 1 PRCCs) and alpha-methylacyl-CoA racemase (AMACR) (diffuse granular cytoplasmic positivity).[19–21] PRCC, similar to clear cell RCC, is thought to arise from proximal renal tubular epithelial cells,[7] with PRCC having better prognosis, clinical outcome, and survival.[8–10]

Oncocytomas became a recognized entity through the work of Klein and Valensi[22] and comprise 3% to 7% of renal tumors.[2,23] Most occur across a broad age range and present asymptomatically.[5,24] The disease-specific survival is nearly 100%.[25] These tumors appear to originate from collecting duct intercalated cells.[23] Cytogenetic abnormalities include loss of chromosomes 1 and Y,[23,26] and more recent data show these tumors may also harbor translocations between chromosomes 6 and 9.[27]

The presence of concurrent RCC within the same kidney as an oncocytoma has been described and most commonly involves clear cell RCC and chromophobe RCC.[28,29] However, the occurrence of PRCC and oncocytoma within the same tumor mass is extremely rare and poorly understood.[30–33] In this report, we present a unique case of PRCC associated with an oncocytoma with trisomy 17 identified by fluorescence in situ hybridization (FISH) in the PRCC component, as well as review the limited literature available on this rare type of collision tumor.

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