Minimal fat renal angiomyolipoma with central scar and stellate calcification mimicking a calyceal calculus

Low, Eugene; Tan, Cher Heng; Ho, Bernard; Chong, Simon

doi:10.11622/smedj.2013231

Cited by 1 publication

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“…Radiographic evidence of fat within a renal mass can be seen in both AML and RCC, potentially complicating the radiographic diagnosis of AML versus RCC. Intratumoral adipose in RCC is usually associated with osseous metaplasia [1][2][3][4][5][6][7][8][9][10][11][12][13][14], but AML is also known to rarely present with calcifications [15][16][17][18][19][20]. Furthermore, RCC has been reported to contain adipose without evidence of calcification on CT and/or pathologic analysis [3,[7][8][9]14].…”

Section: Discussionmentioning

confidence: 99%

Clinicopathologic analysis of renal cell carcinoma containing Intratumoral fat with and without osseous metaplasia

et al. 2020

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Background: There is minimal information regarding the prevalence of intratumoral adipose in renal cell carcinoma (RCC), and no study has assessed the impact of intratumoral adipose on the preoperative imaging diagnosis. The aim of this study was to investigate the prevalence and histopathologic characteristics of entrapped adipose with or without osseous metaplasia in RCC nephrectomy specimens and to determine if this finding impacted the preoperative imaging interpretation. Methods: 704 RCC specimens were prospectively evaluated for entrapped adipose and osseous metaplasia (423 partial nephrectomies, 281 total nephrectomies; 327 pT1a, 377 ≥ pT1b; 510 clear cell, 119 papillary, 30 chromophobe, 22 clear cell papillary, 23 other). Imaging reports were obtained, and the presence of intratumoral fat or calcification and the radiologic diagnostic impression were recorded. Results: 3% (n = 21) contained microscopically identified intratumoral adipose, with a similar frequency in the main histologic subtypes (p = 0.76). Mean metaplastic deposit size was 0.4 cm, mean deposit to capsule distance 0.2 cm, and 29% involved the tumor capsule. Histologically identified adipose was infrequently noted via imaging (13%), and only 1 case with histologically identified metaplasia had a radiologic diagnostic differential of angiomyolipoma (1/704, 0.1%). Conclusion: While intratumoral adipose and/or osseous metaplasia can be observed within RCC, it is extremely rare for the radiologic diagnostic impression to have been confounded by histologically identified entrapped adipose. Awareness that metaplastic deposits are usually near the tumor capsule and may be minute could help prevent errors in diagnosis or staging.

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