Abstract
Xp11 translocation renal cell carcinoma (RCC), a member of the microphthalmia-associated transcription factor (MiTF) family, is a rare renal tumor characterized by different translocations involving the TFE3 gene. Here, we reported a case of Xp11 translocation RCC with a rare MED15-TFE3 gene fusion by RNA sequencing. Morphologically, the tumor cells were arranged in a solid and small nest pattern. The cytoplasm was voluminous, flocculent eosinophilic, and vacuolated. The nuclei were round or polygon with fine granular chromatin, and the nucleoli were unconspicuous. Psammoma bodies were observed in mesenchyma. Immunohistochemically, the tumor cells were diffuse moderately or strongly positive for CD10, P504S, vimentin, PAX8, RCC, AE1/AE3, and SDHB and focally positive for CK7 and CA IX while negative for cathepsin K, HMB45, Melan-A, Ksp-cadherin, and CD117. The Ki67 proliferation index was approximately 3%. However, TFE3 labeling showed an uncertainly weak nuclear staining and been considered negative. Fluorescence in situ hybridization (FISH) demonstrated a positive result that splits signals with a distance of > 2 signal diameters. Subsequently, RNA sequencing confirmed a fusion of MED15 gene exon 11 on chromosome 22 with TFE3 gene exon 6 in the tumor. The patient was alive with no evidence of recurrence. Our report contributes to the understanding on MED15-TFE3 RCC.
Highlights
Microphthalmia-associated transcription (MiT) family translocation renal cell carcinoma, consisted of Xp11 tRCC and t(6; 11) RCC, is a distinct cancer subtype named in 2016 WHO classification of renal tumor [1]
Abdominal computed tomography (CT) scan revealed a cystic solid density lesion at the lower pole of her left kidney, which protruded the renal parenchyma with a clear boundary
Renal carcinoma associated with Xp11.2 translocations/ TFE3 gene fusions is an unusual renal tumor, which is recognized as an entity in 2004 WHO classification of tumors of the urinary system [1, 21]. e majority (40%) of paediatric RCCs are Xp11 translocation RCCs, whereas approximately 1.6–4% of adult RCCs are Xp11 translocation RCCs [2,3,4]. e most common histological pattern of the Xp11 translocation RCCs is that of a papillary neoplasm composed of epithelioid clear cells with abundant psammoma bodies [5]
Summary
Microphthalmia-associated transcription (MiT) family translocation renal cell carcinoma (tRCC), consisted of Xp11 tRCC and t(6; 11) RCC, is a distinct cancer subtype named in 2016 WHO classification of renal tumor [1]. Xp11 tRCC is featured by a short arm of X chromosome translocation with other chromosomes, leading to TFE3 gene fusion. It is commonly reported in children and young adults, especially in young women, accounting for about 40% of RCC in children and 1.6–4% in adults [2,3,4]. E morphological manifestations of Xp11 tRCC are diverse They are occasionally confused with other common types of RCCs. TFE3 translocation-associated RCC was divided into different genotypes according to the target genes of the translocation. Inadequate description has been given on it by WHO histological classification of RCC due to rarity
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