Heterotopic Ossification in Benign and Malignant Renal Neoplasms

Abstract

Abstract Introduction/Objective Heterotopic bone formation in renal neoplasms is a rare phenomenon. Ossification with or without marrow elements has been reported in both benign and malignant renal tumors. Due to its rarity, the epidemiological and clinical features of this finding are not well-documented. Herein, we have examined heterotopic ossification in renal neoplasms and summarized the epidemiological and clinical features of this entity. Methods/Case Report A database search on PubMed, Scopus, and Google Scholar was performed using a combination of proper search terms. Full article texts of all search results were reviewed with reference lists screened for additional articles matching the search criteria. The demographic details of the patients, disease characteristics, treatment, and outcomes were all extracted from full text articles and were summarized in a pre-standardized form. The inclusion criteria were set as any epithelial renal neoplasm with histological evidence of heterotopic ossification. A case of clear cell renal cell carcinoma (CCRCC) with heterotopic ossification diagnosed in our institution is included in the study. Results (if a Case Study enter NA) A total of 30 cases were found of renal neoplasms with bone formation. The majority of patients were between the ages of 40 to 60. The male to female ratio was 1:1. The majority (19/30) were histologically diagnosed as CCRCC, the most common subtype of kidney tumor with a few cases diagnosed as chromophobe RCC (4/30), papillary RCC (3/30), and cystic nephroma (2/30). Of the neoplasms reported, tumor size varied from 3.0 cm to 28.8 cm. Conclusion Heterotopic ossification of renal neoplasms often presents a diagnostic challenge to the radiologist as other benign conditions such as extramedullary hematopoiesis can be in the differential. The rarity of this phenomenon renders pre-surgical diagnosis difficult. Our study documents this phenomenon to be seen in a variety of renal neoplasms and underscores the necessity to be aware of this rare entity.