Accurate diagnostic criteria should be used in correlation studies comparing histology and radiologic findings. Histology is the reference standard for the diagnosis of angiomyolipoma. In the current World Health Organization (WHO) classification of renal neoplasms, two histotypes of angiomyolipoma are reported: classic and epithelioid angiomyolipoma. Other histologic variants, such as oncocytic and cystic angiomyolipoma have been described. Lane et al. [1] define monophasic angiomyolipomas composed predominantly (95% or more) of smooth muscle (monotypic leiomyomatous variant) or of fat (lipomatous variant). This distinction is not reported in the WHO classification or in current surgical pathology textbooks [2, 3]. In the histopathologic literature, the terms “fat-pure angiomyolipoma” or “angiomyolipoma with minimal fat” have not been reported. This terminology is used by radiologists and should not be accepted as a conclusive diagnosis because the histologic examination has not been performed and the entity of neoplastic single components is unclear. We have read with great interest the article, Histogram Analysis of Small Solid Renal Masses: Differentiating Minimal Fat Angiomyolipoma From Renal Cell Carcinoma, by Chaudhry et al. [4]. These authors examined 20 “minimal fat renal angiomyolipomas” obtained by biopsy or surgical resection. They do not specify the number of angiomyolipomas diagnosed by biopsy or the number of core needle biopsies that were obtained. Consequently the fat content could not be established with accuracy because only complete histologic examination of the lesion permits determination of the fat at ≤ 25% per high-power field. These cases should be excluded from the study. The diagnosis of minimal fat angiomyolipoma is based on radiologic findings and should be avoided because these variants have been not reported in the histologic classification. We propose that the term “minimal fat angiomyolipoma” should be changed to angiomyolipoma with an indication of the exact percentage of fat content. Only a complete histologic examination of the entire lesion can establish the exact fat content.

Minimal Fat Angiomyolipoma: A Controversial Subtype of Classic Angiomyolipoma

SCIALPI, Michele
2013

Abstract

Accurate diagnostic criteria should be used in correlation studies comparing histology and radiologic findings. Histology is the reference standard for the diagnosis of angiomyolipoma. In the current World Health Organization (WHO) classification of renal neoplasms, two histotypes of angiomyolipoma are reported: classic and epithelioid angiomyolipoma. Other histologic variants, such as oncocytic and cystic angiomyolipoma have been described. Lane et al. [1] define monophasic angiomyolipomas composed predominantly (95% or more) of smooth muscle (monotypic leiomyomatous variant) or of fat (lipomatous variant). This distinction is not reported in the WHO classification or in current surgical pathology textbooks [2, 3]. In the histopathologic literature, the terms “fat-pure angiomyolipoma” or “angiomyolipoma with minimal fat” have not been reported. This terminology is used by radiologists and should not be accepted as a conclusive diagnosis because the histologic examination has not been performed and the entity of neoplastic single components is unclear. We have read with great interest the article, Histogram Analysis of Small Solid Renal Masses: Differentiating Minimal Fat Angiomyolipoma From Renal Cell Carcinoma, by Chaudhry et al. [4]. These authors examined 20 “minimal fat renal angiomyolipomas” obtained by biopsy or surgical resection. They do not specify the number of angiomyolipomas diagnosed by biopsy or the number of core needle biopsies that were obtained. Consequently the fat content could not be established with accuracy because only complete histologic examination of the lesion permits determination of the fat at ≤ 25% per high-power field. These cases should be excluded from the study. The diagnosis of minimal fat angiomyolipoma is based on radiologic findings and should be avoided because these variants have been not reported in the histologic classification. We propose that the term “minimal fat angiomyolipoma” should be changed to angiomyolipoma with an indication of the exact percentage of fat content. Only a complete histologic examination of the entire lesion can establish the exact fat content.
2013
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1149077
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