OBJECTIVE: First described in 2014, renal cell carcinoma (RCC) with TFEB amplification (6p21) is a rare molecular subgroup whose diagnosis is challenging. The prognosis and therapeutic implications remain unclear.
METHODS: We report here the clinical, histological, immunohistochemical, and genetic features of nine novel cases. The pathological and immunohistochemical features were centrally reviewed by expert uropathologists. Fluorescence in situ hybridisation (FISH) confirmed the diagnosis and comparative genomic hybridisation (CGH) was performed to determine quantitative genomic alterations. We also performed an exhaustive review of the literature and compiled our data.
RESULTS: TFEB-amplified RCC were locally advanced, with initial lymph node involvement in one case and liver metastasis in another case. They were high-grade eosinophilic tumours with papillary/pseudopapillary architecture, frequent positivity for melanocytic markers, and frequent PDL1 expression. FISH demonstrated high-level TFEB amplification in six cases. One case showed concomitant TFEB translocation. CGH analysis identified complex alterations with frequent losses of 1p, 2q, 3p, 6p, and frequent 6p and 8q gains. VEGFA coamplification was identified in all cases with a lower level than TFEB. The prognosis was poor, with five patients having lymph node or distant metastases.
CONCLUSIONS: TFEB-amplified RCC is a rare molecular subgroup with variable morphology whose diagnosis is confirmed by FISH analysis. The complex alterations identified by CGH are consistent with an aggressive clinical behaviour. The coamplification of VEGFA and the expression of PDL1 could suggest a potential benefit from antiangiogenics and targeted immunotherapy in combination for these aggressive tumours.

BACKGROUND: To study the role of lysosomal decomposition and elimination of old bone matrix, as well as the mechanism of promoting chondrocyte growth and bone recovery through the perspective of TFEB-mediated lysosomal autophagy.
METHODS: Rat models of acute knee injury were designed, and autophagy flow was detected by injection of autophagy inhibitors 3-methyladenine. Autophagy flow was detected by RFP-GFP-LC3 double fluorescence molecule. The expression of TFEB, DRAM, MAPLC3, and MITF were analyzed by Western blot, and the expression of genes NITF, Bcl2, and TYR in rat cartilage tissues were detected by RT-PCR.
RESULTS: The number of autophagosomes was increasing in the auto group compared with the inhibitor-auto group and normal group. There was a significant difference of LC3 levels in the auto group and inhibitor-auto group compared with the normal control. The expression of TFEB, DRAM, MAPLC3, and MITF proteins by Western blot analysis were significantly increased in the auto group and decreased in the inhibitor-auto group. The expression of NITF, Bcl2, and TYR by RT-PCR determination were higher in the auto group and inhibitor-auto group than the normal group.
CONCLUSIONS: Autophagy can inhibit apoptosis, promote chondrocyte growth and bone regeneration, and restore knee joint injury of rats. The main mechanism is to promote the effect of TFEB-mediated lysosomal autophagy.

t(6;11)(p21;q12)/TFEB gene fusion-associated renal cell carcinoma is a recently recognized renal cell carcinoma caused by the formation of Alpha-TFEB fusion genes. Herein, we have reported a rare case. A 20-year-old female patient presented with a mass measuring 4.1 cm × 3.3 cm in left kidney, and radical left nephrectomy was performed. Then the patient underwent unmarkable prognosis without recurrence or metastasis in the 18-month follow-up. Microscopic findings showed the tumor mainly composed of medium and large epithelioid cells with the structures of solid nesting and pseudopapillary. The tumor cells showed well-circumscribed, abundant eosinophilic cytoplasm and obvious small nucleoli. Furthermore, multifocal hemosiderin deposition and focal osseous metaplasia were observed. The tumor cells were positive for E-cadherin and focally positive for HMB45, Melan-A, AE1/AE3, Vimentin, RCC and CK19. FISH analysis for TFEB break-apart probe revealed a break-apart signal pattern meaning TFEB gene rearrangement. t(6;11)(p21;q12)/TFEB gene fusion-associated renal cell carcinoma is a rare tumor that mostly occurs in young adults with a beneficial prognosis. Diagnosis is usually performed according to the age of the patients, the pathologic morphology and immunophenotype. Positive TFEB expression in neoplastic cell nuclei can be regarded as sensitive and specific diagnostic event for this type of tumor. TFEB gene break-apart and rearrangement in FISH test is crucial to the diagnosis of the disease.

Renal cell carcinoma with TFEB rearrangement (t[6;11][p21;q13]) was initially recognized to be composed of dual populations of large cells with clear cytoplasm and small cells forming rosettes around hyaline material. With increasing awareness, however, the spectrum of described morphology has been found to be more heterogeneous. We report a 54-year-old woman who underwent partial nephrectomy for a 2.4-cm renal mass, composed of fibrosis, hyalinization, calcification, and ossification and a smaller component of epithelioid cells. Immunohistochemical staining revealed diffuse positivity for cytokeratin AE1/AE3 and PAX8, patchy labeling for melan-A, human melanosome, and cathepsin K, and negative caldesmon, smooth muscle actin, TFE3 protein, carbonic anhydrase IX, CD10, cytokeratin 7, epithelial membrane antigen, and inhibin. Fluorescence in situ hybridization confirmed rearrangement of TFEB and not TFE3. Together with one recent case in another report, our findings suggest that extensive sclerosis and ossification may be a less common recurring histology of TFEB-rearrangement renal cell carcinoma.