TSC2 nonsense mutation in angiomyolipoma with epithelial cysts: a case report and literature review.

Background: Angiomyolipoma with epithelial cysts (AMLEC) is an extremely rare subtype of kidney angiomyolipoma that contains epithelial-lined cysts. The most distinctive immunohistochemical feature of AMLEC is its immunoreactivity with melanocytic markers. AMLEC also has a distinct histological structure, which aids in its pathological diagnosis. To date 27 cases of AMLEC have been reported in 11 case series. However, the molecular biology underlying the pathogenesis of AMLEC remains unexplored. Case report: A 30-year-old female was diagnosed with AMLEC and underwent partial nephrectomy. Histologically, the cross-section of cystic tissue revealed a multilocular appearance, with some cysts containing thrombus-like material, and the wall thickness was approximately 0.2 ~ 0.3 cm. Additionally, the compact subepithelial cellular stroma showed strong and diffuse nuclear labeling for estrogen receptor, progesterone receptor, and CD10, as well as HMB45 and Melan A, which are markers of melanocytic differentiation. Furthermore, using a DNA targeted sequencing panel with next-generation sequencing, we identified a nonsense mutation in TSC Complex Subunit 2 (TSC2) gene, resulting in the formation of a premature termination codon. Moreover, the mutated genes found to be enriched in the PI3K-AKT pathway. The patient in this case had a favorable postoperative follow-up at 3 months. Conclusion: To the best of our knowledge, this study represents the first analysis of genotype mutations in AMLEC, providing valuable insights for future clinical practice. These findings have significant potential in guiding the understanding and management of AMLEC, paving the way for further research and advancements in the field.

Concurrent Eosinophilic Solid and Cystic Renal Cell Carcinoma and Angiomyolipoma With Epithelial Cysts in the Setting of Tuberous Sclerosis Complex: A Rare Synchronous Occurrence of 2 Distinct Entities.

Eosinophilic solid and cystic renal cell carcinoma (ESCRCC) is a recently described distinct renal neoplasm known to occur almost exclusively in female patients with or without tuberous sclerosis complex (TSC). We report a case of ESCRCC with 2 synchronous angiomyolipomas, including 1 angiomyolipoma with epithelial cysts (AMLEC), a rare cystic variant of AML that typically arises sporadically in the absence of TSC, in a 46-year-old woman with TSC. Besides additional copy number alterations identified in ESCRCC via molecular karyotyping, we also report a unique histologic feature of TSC-associated ESCRCC previously not described in detail, with formation of semicircular multinucleated neoplastic giant cells engulfing an additional intact neoplastic cell, simulating emperipolesis. To the best of our knowledge, this is the first reported case of ESCRCC with concurrent AMLEC in a patient with TSC, confirmed through additional genetic testing showing a germline heterozygous mutation in TSC1. Awareness of ESCRCC helps avoid the pitfall of a diagnosis of unclassified renal cell carcinoma, a typically much more aggressive tumor.

Smooth muscle and adenoma-like renal tumor: a previously unreported variant of mixed epithelial stromal tumor or a distinctive renal neoplasm?

We describe 6 cases of a biphasic renal neoplasm, which we designate smooth muscle and adenoma-like renal tumor, which do not cleanly fit any category as currently defined. There were 4 females and 2 males (age, 27-70 years); neither male had a history of hormone exposure. All 5 neoplasms with available history were discovered incidentally on imaging studies with sizes ranging from 4 to 20 cm. The stroma was composed of smooth muscle fascicles alternating with looser, edematous areas; none of the cases contained ovarian-like stroma. The complex but cytologically benign epithelial component consisted of tubulopapillary nodules, branching tubules, clefts, and large cysts. The stroma of all of the cases labeled diffusely for desmin. Estrogen receptor labeling was absent in 4 cases with only minimal (<10%) weak labeling in the remaining 2. The epithelial component of each case labeled diffusely for cytokeratin 7 and was patchy for α-methyl-CoA racemase (P504S). Carbonic anhydrase IX, HMB45, WT-1, and inhibin were negative. None of the 5 cases tested demonstrated trisomies of chromosome 7 or 17 by fluorescence in situ hybridization. Two patients with significant follow-up are disease free at 18.5 and 2.5 years. Smooth muscle and adenoma-like renal tumor could potentially represent a variant of mixed epithelial stromal tumor, which would expand its reported spectrum. However, the absence of clinical history of hormone exposure, predominance of smooth muscle with lack of ovarian-like stroma, prominence of epithelial nodules, and typical absence of estrogen receptor labeling suggest that it may represent a distinct entity.