Pathology Unit, Department of Medical and Surgical Sciences, University of Cantabria, Santander, Spain;
Rom J Morphol Embryol. 2021 Jul-Sep;62(3):663-670. doi: 10.47162/RJME.62.3.02.
Renal oncocytoma (RO) is a distinctive neoplasm with a well-recognized gross and cytoarchitectural appearance. However, on some occasions, it may show uncommon, atypical, or worrisome gross and microscopic features potentially generating diagnostic difficulties. We herein review the oncocytoma variant characterized by a significant intraneoplastic xanthomatous reaction that produces a variegated macroscopic appearance. This feature may pose a genuine diagnostic problem with conventional (clear cell) renal cell carcinoma (RCC) because this reaction creates a departure from the typical uniform, tan-brown appearance of oncocytoma. The microscopic presence of foamy macrophages in RO may potentially lead to diagnostic difficulties with tumors exhibiting eosinophilic cells and significant infiltration for lipid-laden foamy macrophages such as cystic RCC, unclassified RCC rich in foamy macrophages, the solid variant of papillary RCC with oncocytic features, post-neuroblastoma RCC, succinate dehydrogenase-deficient RCC, mucinous-poor tubular and spindle cell carcinoma, and the oncocytic variant of the epithelioid angiomyolipoma. In conflictive cases, an immunohistochemical panel should help to solve the diagnostic problem. Therefore, the presence of abundant foamy macrophages should not dissuade the pathologist from establishing a diagnosis of RO. Prominent xanthomatous reaction despite its low frequency (4.3%) can be considered an additional feature of RO. Thus, RO should be added to the list of renal tumors that can show a significant reaction of lipid-laden foamy macrophages. Besides, Gamna-Gandy bodies can be present in this tumor.
肾嗜酸细胞瘤（RO）是一种具有明显的大体和细胞结构特征的独特肿瘤。然而，在某些情况下，它可能表现出不常见的、非典型的或令人担忧的大体和显微镜特征，可能导致诊断困难。本文回顾了一种以显著的瘤内黄色瘤反应为特征的嗜酸细胞瘤变异型，其产生斑驳的大体外观。这种特征可能会对常规（透明细胞）肾细胞癌（RCC）的诊断产生真正的问题，因为这种反应偏离了嗜酸细胞瘤典型的均匀棕褐色外观。RO 中泡沫状巨噬细胞的存在可能会导致与表现出嗜酸性细胞和富含脂质的泡沫状巨噬细胞浸润的肿瘤（如囊性 RCC、富含泡沫状巨噬细胞的未分类 RCC、具有嗜酸细胞特征的乳头状 RCC 的实性变异型、神经母细胞瘤后 RCC、琥珀酸脱氢酶缺陷型 RCC、黏液性管状和梭形细胞癌以及上皮样血管平滑肌脂肪瘤的嗜酸细胞瘤变异型）的诊断困难。在有争议的情况下，免疫组织化学组化应该有助于解决诊断问题。因此，大量泡沫状巨噬细胞的存在不应阻止病理学家做出 RO 的诊断。尽管黄色瘤反应的频率较低（4.3%），但它可以被认为是 RO 的另一个特征。因此，RO 应该被添加到可以显示大量富含脂质的泡沫状巨噬细胞反应的肾肿瘤列表中。此外，该肿瘤中也可以存在 Gamna-Gandy 体。
