Yin Xiaoxue, Zhang Xingming, Pan Xiuyi, Tan Junya, Zheng Linmao, Zhou Qiao, Chen Ni
Department of Pathology, Laboratory of Pathology, West China Hospital, West China Medical School, Sichuan University, Chengdu, China.
Department of Urology, West China Hospital, West China Medical School, Sichuan University, Chengdu, China.
Front Oncol. 2022 Oct 14;12:1020456. doi: 10.3389/fonc.2022.1020456. eCollection 2022.
Metanephric adenomas (MAs) are rare, benign renal tumors. Wilms' tumors (WTs) are malignant embryonic tumors that originated from nephrogenic blastemal cells. However, some tumors have similar morphology to both MA and epithelial-predominant WT, which makes differential diagnosis difficult. We aimed to analyze the morphological, immunophenotypic and molecular changes in overlapping cases to explore their attribution.
Twenty MAs, ten WTs, and nine cases with MA/WT overlapping histological features were studied. Twenty tumors demonstrated the typical morphological spectrum of MA with high cellularity and were composed of tightly packed small, uniform, round acini with a lower Ki67 index. Almost all MAs (94.7%, 18/19) were detected with V600E mutation. The ten WTs were epithelial-predominant WTs with glands, rosettes and glomerular structures, which also showed a higher Ki-67 index (up to 60%), invasive growth patterns, and a lack of mutation. However, the other nine overlapping cases showed two components: typical MA-like areas and epithelial WT-like areas. The cells of the WT-like areas were tubular, columnar and showed marked cytological atypia, with a Ki-67 proliferative index of up to 30%. The immunophenotype of these overlapping lesions was not significantly different from that of typical MA and they positively expressed WT1 and CD57. The V600E mutation was detected in both WT-like and MA-like areas in nine overlapping tumors. The follow-up data of 31 patients were analyzed, with a median follow-up time of 66 months (range, 8-45 months). Even though most patients with WT underwent radiotherapy or chemotherapy after surgery, two died, and one had liver metastasis. No MA or overlapping cases showed any evidence of recurrence or metastasis after surgery.
The molecular changes in tumors with overlapping morphological features were the same as those of typical MA; thus, we think that these tumors should be classified as MA and further called atypical MA. It is important to note that atypical MA is not a neglected subtype of MA. It possesses different histological morphology and a higher Ki-67 index but has the common imaging characteristics, immunophenotype and gene expression as typical MA, and patients usually have a good prognosis.
后肾腺瘤（MA）是一种罕见的良性肾肿瘤。肾母细胞瘤（WT）是起源于肾胚基细胞的恶性胚胎性肿瘤。然而，一些肿瘤在形态上与MA和上皮为主型WT都相似，这使得鉴别诊断困难。我们旨在分析重叠病例的形态学、免疫表型和分子变化，以探讨其归属。
研究了20例MA、10例WT和9例具有MA/WT重叠组织学特征的病例。20例肿瘤表现出典型的MA形态谱，细胞密度高，由紧密排列的小而均匀的圆形腺泡组成，Ki67指数较低。几乎所有的MA（94.7%，18/19）都检测到V600E突变。10例WT为上皮为主型WT，具有腺体、玫瑰花结和肾小球结构，其Ki-67指数也较高（高达60%），呈浸润性生长模式，且无突变。然而，另外9例重叠病例表现为两种成分：典型的MA样区域和上皮WT样区域。WT样区域的细胞呈管状、柱状，细胞学异型性明显，Ki-67增殖指数高达30%。这些重叠病变的免疫表型与典型MA无明显差异，均阳性表达WT1和CD57。9例重叠肿瘤的WT样区域和MA样区域均检测到V600E突变。分析了31例患者的随访数据，中位随访时间为66个月（范围8 - 45个月）。尽管大多数WT患者术后接受了放疗或化疗，但仍有2例死亡，1例发生肝转移。没有MA或重叠病例术后出现复发或转移的迹象。
形态学特征重叠的肿瘤分子变化与典型MA相同；因此，我们认为这些肿瘤应归类为MA，可进一步称为非典型MA。需要注意的是，非典型MA并非被忽视的MA亚型。它具有不同的组织学形态和较高的Ki-67指数，但具有与典型MA相同的影像学特征、免疫表型和基因表达，患者通常预后良好。
