Osseous Metaplasia in Mucinous Tubular and Spindle Cell Carcinoma of the Kidney: A Case of Massive, Bilateral Tumors

Abstract

Renal cell carcinoma (RCC) is the most common kidney malignancy, with many histologic subtypes. One of the rare forms of RCC is mucinous tubular and spindle cell carcinoma (MTSCC), which is newly described with limited information on clinical picture and outcome. Heterotopic bone formation (osseous metaplasia) is a rare finding within any renal mass. Here we report a case of a massive, bilateral MTSCC with histologic findings of heterotopic bone formation, which has not been described before.

Renal cell carcinoma with osseous metaplasia: A case report and literature review

“…Osseous metaplasia has also been reported in patients with renal diseases, including less than 20 cases of the major subtypes of RCC [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][23][24][25][26]. Table 1 summarizes clinicopathologic features of these cases, including the present case, reported in case studies of osseous metaplasia associated with RCC.…”

“…Hypotheses include osteoblast metaplasia of tumor cells and metaplastic changes of pluripotent stromal cells to osteoblasts by factors secreted by tumor cells [30]. In RCC, osseous metaplasia was suggested to represent secondary changes to ischemia, hemorrhage, necrosis, fibrosis, and/or hyalinization [2,25]. The involvement of BMP2 in ossification of RCC has also been documented [31,32].…”

Clear cell renal cell carcinoma with heterotopic bone formation: A case report and literature review

“…Heterotopic bone formation has been described in the context of clear cell, chromophobe, papillary, mucinous tubular, as well as spindle cell RCC, both in the presence and absence of sarcomatoid features. [2][3][4][5][6][7][8] The presented case describes heterotopic bone formation and mature adipose tissue associated with clear cell RCC without sarcomatoid differentiation.…”