Objective: To investigate the clinicopathological characteristics, immunophenotypes, diagnostic criteria and differential diagnosis of atrophic kidney-like lesion (AKLL). Methods: Three cases of AKLL were collected from April 2021 to October 2023 at the Xiangya Hospital of Central South University, Changsha, Zhejiang Provincial People's Hospital, Hangzhou and Ningbo Clinical Pathology Diagnosis Center, Ningbo, China. The clinical, morphological, and immunohistochemical characteristics were analyzed. Relevant literature was also reviewed. A targeted DNA-based next-generation sequencing (a panel of 150 genes) was performed on one of the three cases. Results: There were 1 female and 2 males, aged 30, 57, and 17 years (mean 34.6 years), respectively. The lesions were all incidentally identified during physical or imaging examination. Radiologically, they were all presented as a unilateral renal parenchymal mass. Grossly, the maximum diameters of the lesions were 1.8, 4.0, and 6.5 cm (mean 4.1 cm), respectively. The tumor cut-surfaces were sponge-like, multilocular cystic, and solid, respectively. At low magnification, the lesions were well-circumscribed, while a thick fibromuscular capsule was noted in cases 1 and 3. Cases 1 and 2 were composed of thin-walled cysts or follicular like structures of varying sizes, with the cyst wall lined by flattened and atrophic, or hobnail cells. The luminal spaces contained dense eosinophilic secretion and associated calcifications, while some cysts contained discohesive cells floating in the eosinophilic material. The tissue between the cysts showed predominantly small atrophic tubular structures. Case 3 was almost entirely composed of atrophic and collapsed tubular structures with focal cyst formation, imparting a solid sheets growth pattern under low magnification. Immunohistochemical staining revealed that the cyst lining cells and the intracystic floating cells were WT1 positive, PAX8 negative and CK7 negative, while the atrophic renal tubules were WT negative, PAX8 positive and CK7 positive. Targeted next-generation sequencing in case 1 showed no significant genetic abnormalities. All 3 patients underwent partial nephrectomy. No evidence of recurrence or metastasis was found with a follow-up of 17 to 36 months. Conclusions: AKLL is a rare and novel benign renal disease. It is easily misdiagnosed as a renal neoplasm grossly and histologically. Careful morphological observation combined with characteristic immunophenotypes can aid in its diagnosis and differential diagnosis.
目的： 探讨萎缩肾样病变（atrophic kidney-like lesion，AKLL）的临床病理特征、免疫表型以及诊断和鉴别诊断要点。 方法： 观察和分析2021年4月至2023年10月3例AKLL（分别来自中南大学湘雅医院、浙江省人民医院、宁波市临床病理诊断中心）的临床特征、形态学及免疫组织化学特点，并复习相关文献。对1例行基于150基因套餐的靶向DNA二代测序。 结果： 患者女性1例（例1），男性2例（例2、3），年龄分别为30、57和17岁（平均34.6岁）。病变均为体检或影像学检查偶然发现，影像学上均表现为单侧肾实质的占位性病变。大体上，病变最大径1.8、4.0、6.5 cm（平均4.1 cm），切面分别为海绵状、多房囊性及实性。低倍镜下，病变边界清楚，例1和3可见厚的纤维肌性包膜。例1和2由大小不等的薄壁囊肿或滤泡样结构组成，囊壁内衬扁平或靴钉样细胞。囊内含嗜酸性分泌物伴钙化，部分囊内可见漂浮的游离的细胞群。囊肿之间主要为萎缩的肾小管。例3几乎完全由萎缩的肾小管组成伴局灶的囊性扩张，在低倍镜下呈现实性片状生长。免疫组织化学染色，囊肿被覆细胞以及囊内漂浮的细胞群显示表型WT1+/PAX8-/CK7-，而萎缩的肾小管显示表型WT-/PAX8+/CK7+。例1行二代测序未见有意义的基因异常。3例均行部分肾切除术，术后随访36、17、21个月均未见复发或转移。 结论： AKLL是一种罕见而独特的良性肾疾病，在大体和组织学上均易误诊为肾肿瘤。仔细的形态学观察并辅以特征性的免疫标志物可助于其诊断和鉴别诊断。.