Gene of the month: TFE 3

PEComa with ASPSCR1::TFE3 fusion: expanding the molecular genetic spectrum of TFE3-rearranged PEComa with an emphasis on overlap with alveolar soft part sarcoma

AIMS

Mesenchymal neoplasms involving TFE3 gene fusions are diverse, mainly include alveolar soft part sarcoma (ASPS) that is characterised by ASPSCR1::TFE3 fusion, and a small subset of perivascular epithelioid cell tumours (PEComas) referred to as TFE3-rearranged PEComa, that most frequently harbours SFPQ::TFE3 fusion. Historically, ASPS and TFE3-rearranged PEComa are considered two distinctive entities despite their known morphological overlap. However, recent studies have suggested a potential histogenetic relationship between them, and several neoplasms that showed morphological features more closely fit PEComa rather than ASPS but harboured ASPSCR1::TFE3 fusion have been documented. In this study, we report three cases of PEComa with ASPSCR1::TFE3 fusion.

METHODS AND RESULTS

Clinicopathological features were assessed and partner agnostic targeted next-generation sequencing on clinically validated platforms were performed. The patients are two females and one male with age at presentation ranging from 21 to 51 years. All three tumours were located in the viscera (rectum, kidney and cervix). On a relatively limited follow-up period (range = 9-15 months), all patients are alive without evidence of recurrent or metastatic disease. The neoplasms were composed of tight nested architecture of epithelioid clear cells separated by a delicate vascular network, two of which were associated with sheets of plump spindle cells, and none showed significant discohesive tumour morphology. Immunohistochemically, in addition to TFE3 protein, all three neoplasms demonstrated co-expression of melan-A and smooth muscle actin. RNA-sequencing identified ASPSCR1::TFE3 fusion in all three cases that were confirmed by subsequent fluorescence in-situ hybridisation analyses.

CONCLUSIONS

Our study expands the molecular genetic spectrum of TFE3-rearranged PEComa and further indicates its close relationship to ASPS.

TFE3 nuclear expression as a novel biomarker of ovarian sclerosing stromal tumors and associated with its histological morphology

Sclerosing stromal tumors of the ovary are benign and tend to occur in youthful women with lobular structures at low frequencies. Three types of cells, including luteinized cells, short spindle myoid cells, and intermediate cells, are found in the lobules which abundant in the blood vessels. Currently, immunohistochemistry is used to detect normal follicles, sclerosing stromal tumors, granulosa cell tumors, and fibromas/thecomas. Our research results showed that transcription factor enhancer 3 (TFE3) was moderate to strong positive in the theca interna layer of normal follicles. TFE3 was expressed in seven out of eight sclerosing stromal tumors, mainly in luteinized cells. It did not express in 20 granulosa cell tumors. Of the nine fibromas/thecomas, TFE3 was weakly staining in 2 cases and negative in the remaining 7 cases. The expression of TFE3 was also weak in only one microcystic stromal tumor. 8 cases of sclerosing stromal tumors were analyzed by FISH using a TFE3 separation probe, and the results were negative. In short, as a nuclear transcription protein, TFE3 specifically expressed in sclerosing stromal tumors and could serve as a new marker for the diagnosis and differential diagnosis of sclerosing stromal tumors. Moreover, we speculate that TFE3 will promotes the formation of the vascular plexus after entry into the nucleus, which can further explain why sclerosing stromal tumors are different from other ovary sex-cord stromal tumors.

Primary Xp11 translocation PEComa of the testis with SFPQ⁃TFE3 rearrangement: a case report and review of the literature

BACKGROUND

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal tumors with features of both smooth muscle and melanocytic differentiation. A subset of PEComas demonstrate rearrangements involving the TFE3 (Xp11) locus. Xp11 translocation PEComa is a rare neoplasm with special clinicopathological features and a more aggressive behavior. We recently encountered a case of Xp11 translocation PEComa occurring in the testis, with SFPQ⁃TFE3 rearrangement.

CASE PRESENTATION

A 57-year-old male touched a mass in his testis incidentally. MRI revealed a 10 mm diameter mass in the right testis. The patient underwent radical orchiectomy. Gross examination revealed a well-demarcated mass from the surrounding testicular tissue. Microscopically, the tumor mainly displayed nested or sheet-like architecture separated by delicate fibrovascular septa. The tumor cells exhibited marked nuclear atypia and pleomorphism. Immunohistochemistry showed that the tumor cells were strongly positive for cathepsin-K, HMB45 and TFE3. Molecular analysis revealed SFPQ⁃TFE3 gene fusion. Thus, it was diagnosed as primary Xp11 translocation PEComa of the testis.

CONCLUSIONS

The present case reports primary Xp11 translocation PEComa of the testis for the first time, which to our knowledge has not been described in the literature in this anatomic site, where it could potentially be problematic in diagnosis.

Clinicopathological features and prognosis of TFE3-positive renal cell carcinoma

Background

This study aimed to investigate the expression profile of TFE3 in renal cell carcinoma (RCC) and the clinicopathological features as well as prognosis of TFE3-positive RCC.

Methods

Tissue sections from 796 patients with RCC were collected for immunohistochemical staining of TFE3. Molecular TFE3 rearrangement tests were also carried out on the TFE3-positive RCCs using fluorescence in situ hybridization and RNA-sequencing assays. Both clinicopathological features and follow-up information were collected for further analysis.

Results

The present study showed that 91 patients with RCC (91/796, 11.4%) were TFE3 positive expression but only 31 (31/91, 34.1%) of the patients were diagnosed with Xp11.2 translocation RCC. Further, it was found that the patients with TFE3-positive RCCs were more likely to develop lymph node and distant metastasis at diagnosis as well as presented a significantly higher WHO/ISUP nuclear grade and AJCC stage as compared with patients with TFE3-negative RCCs (p<0.01). Results of univariate and multivariate analyses showed that TFE3 positive expression was an independent prognostic factor associated with poor progression-free survival. Further, the findings of survival analysis showed that patients with positive TFE3 expression showed a shorter progression-free survival as compared with the patients with negative expression of TFE3 (p<0.001). In addition, results of the survival analysis found that there was no significant difference in progression-free survival between the Xp11.2 translocation RCC and TFE3-positive non-Xp11.2 translocation RCC groups (p=0.9607).

Conclusion

This study found that nuclear TFE3 expression is not specific to the Xp11.2 translocation RCC. Moreover, the positive TFE3 expression is associated with tumor progression and poor prognosis in patients with RCC irrespective of the presence of TFE3 translocation.

"Papillary Adenoma-like" Renal Tumor with TFE3 Gene Rearrangement, A Potential Precursor to or Early Event in the Development of TFE3 Translocation Renal Cell Carcinoma

MiT family translocation renal cell carcinomas harbor gene fusion involving members of MiT family of transcription factors. Their precursor lesions have not been identified. Herein, we report the first case of small papillary tumors morphologically resembling papillary adenomas but harboring TFE3 gene alteration. The patient was a 23-year old man with multiple small papillary tumors in the right kidney discovered following a gunshot wound injury. These lesions were < 5 mm, well-circumscribed but not encapsulated tubulopapillary proliferation lined with a single layer of cuboidal cells with WHO/ISUP grade 1 or 2 nuclei. The tumor cells were immunoreactive to PAX8, AMACR, high molecular weight cytokeratin, and keratin 7 and negative for CD10, CA9, TTF1, and cathepsin K. Morphologically and immunohistochemically, these lesions were diagnosed as papillary adenomas. TFE3 gene rearrangement was confirmed by fluorescence in-situ hybridization (FISH) using a TFE3 break-apart probe. We term these tumors "papillary adenoma-like" renal tumor with TFE3 gene rearrangement. These tumors are likely a precursor to or represent an early event in the development of TFE3 translocation renal cell carcinomas. An understanding of such tumors to translocation renal cell carcinoma progression can provide insight into the pathogenic mechanism, and ultimately aid the diagnosis and management of translocation renal cell carcinoma.

A Case of TFE3-positive Non-neoplastic Pseudodecidualized Endometrium Presenting as a Cervical Mass

Transcription factor E3 (TFE3) represents a useful target for immunohistochemistry assays in routine surgical pathology practice. This protein has shown nuclear expression in a variety of normal tissues; however, this expression is usually at very low levels, while strong nuclear immunoreactivity of TFE3 has been seen almost exclusively in tumors. We present the case of a 30-year-old female on oral contraceptive pill (drospirenone/ethinylestradiol) and with complaints of dysmenorrhea and menorrhagia. She was found to have a cervical mass on pelvic ultrasound, and the biopsy showed fragments of benign squamous epithelium and polypoid endometrial tissue with stromal pseudodecidualization and abundant mixed inflammation. The pseudodecidualized stromal component showed moderate to strong nuclear staining in ~85% of stromal cells for TFE3. We discuss the intracellular role of TFE3 during inflammatory states and hypothesize that TFE3 expression can be associated with ongoing inflammation. Our case shed light upon the possibility that non-neoplastic environments with an inflammatory background could lead to increased nuclear expression of TFE3. Pathologists should be aware of the possibility of strong nuclear expression of TFE3 in non-neoplastic endometrium to avoid potential misdiagnosis.

Chameleon TFE3-translocation RCC and How Gene Partners Can Change Morphology: Accurate Diagnosis Using Contemporary Modalities

Translocation renal cell carcinoma (tRCC) with TFE3 gene rearrangements has been born as a distinct entity 20 years ago. These relatively rare tumors were notable among other RCC subtypes because of their disproportionally high incidence among children and young adults. Initial reports were focused on describing unifying morphologic criteria and typical clinical presentation. Follow-up studies of ancillary immunohistochemical and hybridization techniques provided additional diagnostic tools allowing recognition of tRCC tumors in practice. However, a growing body of literature also expanded the clinicomorphologic spectrum of tRCCs, to include a significant morphologic overlap with other RCC variants thus blurring the diagnostic clarity of this entity. More recent molecular studies utilizing next-generation sequencing technology accelerated recognition of numerous novel gene partners fusing at different breakpoints with the TFE3 gene. Accumulating data indicates that morphologic and clinical heterogeneity of tRCC could be explained by fusion subtypes, and knowledge of TFE3 partnering genes may be important in predicting tumor behavior. Herein we provided a comprehensive analysis of ∼400 tRCC cases with known TFE3 fusion partners, estimated their relative incidence and summarized clinicomorphologic features associated with most common fusion subtypes. Our data was based on an extensive literature review and had a special focus on comparing immunohistochemistry, fluorescent in situ hybridization and contemporary molecular studies for the accurate diagnosis of tRCC.

Absence of TFE3 Immunoexpression in a Spectrum of Cutaneous Mixed Tumors: A Retrospective Pilot Study

Background: Cutaneous mixed tumors (CMTs) include benign, atypical, and malignant chondroid syringomas. This spectrum of entities is known to be a part of myoepithelial neoplasms, which display considerable genetic heterogeneity. In a previous report, a malignant chondroid syringoma (MCS) demonstrated PHF1-TFE3 gene fusion and strong TFE3 immunohistochemical (IHC) staining. The authors suggested that the MCS is genetically related to tumors with TFE3 rearrangements such as renal cell carcinoma and might have genetic heterogeneity. In this study, we aim to investigate potential TFE3 gene fusions with TFE3 IHC stain in a spectrum of CMTs. Materials: Eleven benign chondroid syringoma (BCS), one atypical chondroid syringoma (ACS), and one malignant chondroid syringoma cases were identified, stained with TFE3 IHC stain, and interpreted based on preset criteria. Results: ACS and MCS cases did not show any staining. In 7 of 11 BCS cases, weak (1+) staining was observed in less than 20% of the tumor cells and were considered negative. Additionally, in one BCS case, weak (1+) and (2+) staining was shown in approximately 15% and less than 1% of the tumor cells, respectively. Based on our positivity criteria, this case was also interpreted as negative. Conclusions: Our study failed to reveal possible TFE3 gene fusion by IHC staining in benign, atypical, and malignant chondroid syringomas. Although the negative staining in MCS suggests a genetic heterogeneity in this entity, further studies with larger case groups are needed for a more definitive conclusion.

mTOR Inhibition Increases Transcription Factor E3 (TFE3) Activity and Modulates Programmed Death-Ligand 1 (PD-L1) Expression in Translocation Renal Cell Carcinoma

The efficacy of programmed cell death protein ligand (PD-L)-1/PD-1 checkpoint blockade in renal cell carcinoma (RCC) remains unknown. The effects of mTOR inhibitors are uncertain, and patients may develop resistance to them. The limited understanding of cancer cell-intrinsic mTOR-mediated pathways remains a challenge in developing effective treatments. Whether transcription factor (TF)-E3 regulates PD-L1 expression and the tumor microenvironment was investigated, and the effects of an mammalian target of rapamycin (mTOR) inhibitor on translocation RCC were explored. TFE3 was overexpressed in clear cell RCC cell lines, and PD-L1 expression was analyzed by Western blot analysis. PD-L1 activity in relation to TFE3 expression in translocation RCC was also analyzed, via TFE3 knockdown and treatment with an mTOR inhibitor. The results were correlated with the gene expression profile, evaluated using digital multiplex analysis. TFE3 and PD-L1 expression were positively correlated in RCC cells. TFE3 overexpression was associated with the expression of PD-L1 in RCC. Furthermore, mTOR inhibition was associated with enhanced PD-L1 expression via TFE3 activation in translocation RCC. These data support the feasibility of combination therapy based on mTOR inhibition and PD-L1 blockade as a novel strategy for the treatment of patients with translocation RCC.

The Network That Never Sleeps

This review describes how Twitter is currently used by laboratory professionals for education, research, and networking. This platform has a global audience. It enables users to post information publicly, easily, rapidly, and free of charge. The absence of hierarchies enables interactions that may not be feasible offline. Laboratory professionals teach thousands of people using text, images, polls, and videos. Academic discussion flourishes without paywalls. Published research is shared faster than ever before, articles are discussed in online journal clubs, and research collaborations are facilitated. Pathologists network globally and make new friends within and beyond their specialty. Pathology departments and residency programs showcase trainees and faculty and celebrate graduations. As users in one time zone go to bed, others who are just waking up begin to read and tweet, creating a 24/7/365 live global online conference. We encourage others to plug into the power of Twitter, the network that never sleeps.