Granular cell tumors overexpress TFE3 without corollary gene rearrangement

Evaluation of TRIM63 RNA in situ hybridization (RNA-ISH) as a potential biomarker for alveolar soft-part sarcoma (ASPS)

Alveolar soft-part sarcoma (ASPS) is a rare soft tissue tumor with a broad morphologic differential diagnosis. While histology and immunohistochemistry can be suggestive, diagnosis often requires exclusion of other entities followed by confirmatory molecular analysis for its characteristic ASPSCR1-TFE3 fusion. Current stain-based biomarkers (such as immunohistochemistry for cathepsin K and TFE3) show relatively high sensitivity but may lack specificity, often showing staining in multiple other entities under diagnostic consideration. Given the discovery of RNA in situ hybridization (RNA-ISH) for TRIM63 as a sensitive and specific marker of MiTF-family aberration renal cell carcinomas, we sought to evaluate its utility in the workup of ASPS. TRIM63 RNA-ISH demonstrated high levels (H-score greater than 200) of expression in 19/20 (95%) cases of ASPS (average H-score 330) and was weak or negative in cases of paraganglioma, clear cell sarcoma, rhabdomyosarcoma, malignant epithelioid hemangioendothelioma, as well as hepatocellular and adrenal cortical carcinomas. Staining was also identified in tumors with known subsets characterized by TFE3 alterations such as perivascular epithelioid cell neoplasm (PEComa, average H-score 228), while tumors known to exhibit overexpression of TFE3 protein without cytogenetic alterations, such as melanoma and granular cell tumor, generally showed less TRIM63 ISH staining (average H-scores 147 and 96, respectively). Quantitative assessment of TRIM63 staining by RNA-ISH is potentially a helpful biomarker for tumors with molecular TFE3 alterations such as ASPS.

Metastatic Epithelioid Pleomorphic Liposarcoma in the Brain: A Case Report

Metastatic soft tissue sarcoma (STS) to the brain is rare, and metastatic pleomorphic liposarcoma (PLPS) to the brain is even rarer. We present the case of a 76-year-old male with an incidental finding of a brain mass on a brain magnetic resonance imaging (MRI) following a head injury. Additionally, multiple pulmonary nodules and a right gluteal mass were discovered. A core biopsy of the right gluteal mass revealed an epithelioid malignant neoplasm expressing transcription factor enhancer 3 (TFE3) by immunohistochemistry (IHC). Subsequently, the left middle fossa brain mass was removed and found to be an epithelioid PLPS, which was positive for TFE3 by IHC but lacked TFE3 rearrangement by fluorescence in situ hybridization (FISH), and negative for murine double minute (MDM2) amplification by FISH. The diagnosis of epithelioid PLPS mainly relies on histomorphology. This paper discusses the clinicopathological correlation of PLPS, including the epithelioid variant, with a focus on cases with brain metastases.

Antiangiogenics in Malignant Granular Cell Tumors: Review of the Literature

Granular cell tumors (GCT) represent 0.5% of all soft tissue sarcomas (STS), and when metastatic, they exhibit aggressive behavior and determine limited survival. Metastatic GCTs are relatively chemo-resistant; however, there is growing evidence of the benefit of using pazopanib and other targeted therapies in this histology. This is a review of the role of pazopanib and other targeted therapies in the treatment of GCTs, along with some insights on pathology and molecular biology described in GCTs. From 256 articles found in our search, 10 case-report articles met the inclusion criteria. Pazopanib was the most employed systemic therapy. The median reported time on therapy with pazopanib was seven months. Eight out of ten patients (80%) experienced disease control with pazopanib, while four out of ten (40%) patients achieved an objective RECIST response. Molecular studies suggested that antitumoral effects of pazopanib in GCT might be due to a loss-of-function of ATP6AP1/2 genes which consequently enhance signaling through several molecular pathways, such as SFKs, STAT5a/b, and PDGFR-β. Other reported targeted therapies for malignant GCTs included pazopanib in combination with crizotinib, which showed disease control for four months in one patient, and a PI3K inhibitor which achieved disease control for nine months in another patient. Dasatinib and megestrol were ineffective in two other different patients. Pazopanib has been demonstrated to be active in advanced GCTs and may be considered as a preferable treatment option.

Atypical granular cell tumor of the urinary bladder: A case report

BACKGROUND

Granular cell tumor (GCT) is a neurogenic tumor mainly occurring in the head and neck. GCT in the genitourinary system is extremely rare and only sporadic cases of urinary bladder GCT have been reported. Most urinary bladder GCT cases are benign and only two malignant cases have been reported. Due to its rarity, no consensus criteria for the treatment of urinary bladder GCT are available at present.

CASE SUMMARY

A 62-year-old Chinese woman was found to have a urinary bladder tumor without any clinical manifestations on physical examination. Cystoscopy revealed a semispherical shaped lesion measuring approximately 4.0 cm in diameter at the junction of the left wall and roof of the bladder, which was covered with normal bladder mucosa. Computed tomography scan demonstrated a high-density lesion on the left wall of the bladder, measuring approximately 2.9 cm × 2.4 cm with clear boundaries. Contrast-enhanced pelvic magnetic resonance imaging revealed a space-occupying lesion on the left wall of the bladder (non-mucosal origin/ external pressure), which was preliminarily suspected to be a desmoplastic fibroma or leiomyoma. In the context of the above findings, a pre-operative diagnosis of bladder leiomyoma was made. The patient consequently underwent a laparoscopic partial cystectomy. The resected bladder mass looked yellowish and well-demarcated, measuring 4.0 cm × 3.5 cm and infiltrated the muscular layer. The diagnosis of urinary bladder GCT was finally made by postoperative pathology, with positive immunohistochemical S-100 staining and negative pancytokeratin. The patient has been followed for 6 mo so far, with no tumor recurrence detected.

CONCLUSION

This case highlights the biological feature and differential diagnosis of urinary bladder GCT at the pathological and molecular levels. Transurethral resection of the bladder tumor and partial cystectomy are recommended in most urinary bladder GCT cases, while radical cystectomy is recommended in malignant cases.

Recent developments in gastroesophageal mesenchymal tumours

The pathologist's approach to gastroesophageal mesenchymal tumours has changed dramatically during the last 25 years. In particular, gastrointestinal stromal tumour (GIST) has evolved from a wastebasket mesenchymal tumour category to a precisely defined entity with an increasingly detailed genetic subclassification. This subclassification has brought gastrointestinal mesenchymal neoplasia into the realm of precision medicine, with specific treatments optimised for particular genetic subtypes. Molecular genetic data have also greatly improved our understanding of oesophageal mesenchymal tumours, including the discovery that so-called 'giant fibrovascular polyps' in fact represent a clinically distinctive presentation of well-differentiated liposarcoma. Here, we will focus on gastroesophageal mesenchymal tumours for which there have been recent developments in classification, molecular genetics or tumour biology: granular cell tumour, 'giant fibrovascular polyp'/well-differentiated liposarcoma, plexiform fibromyxoma, gastroblastoma and, of course, GIST.

Gene of the month: TFE 3

Transcription factor enhancer 3 (TFE3), on the short arm of chromosome Xp11.23 and its protein, belongs to the microphthalmia transcription family (MiTF) of transcription factors. It shares close homology with another member of the family, MiTF which is involved in melanocyte development. When a cell is stressed and/or starved, TFE3 protein translocates into the nucleus. TFE3 gene fusions with multiple different partner genes occur in several tumours with resultant nuclear expression of TFE3 protein. The main tumours associated with TFE3 gene fusions are: renal cell carcinoma, alveolar soft part sarcoma, a subset of epithelioid haemangioendotheliomas (EHE), some perivascular epithelioid cell tumours and rare examples of ossifying fibromyxoid tumour and malignant chondroid syringoma. TFE3 immunohistochemistry is of use in routine diagnostic practice with the aforementioned tumours harbouring TFE3 fusions leading to nuclear staining. In addition, there are tumours lacking TFE3 fusions but also display TFE3 nuclear immunolabeling, and these include: granular cell tumour, solid pseudopapillary neoplasm of the pancreas and ovarian sclerosing stromal tumour.

The Diagnostic and Clinical Significance of TFE3 Immunohistochemical Nuclear Expression in Solitary Fibrous Tumour

The expression of TFE3 (transcription factor E3) in solitary fibrous tumours (SFTs) and their histologic mimickers was investigated, and the diagnostic value and clinical significance of TFE3 nuclear expression in SFTs were explored. Immunohistochemical analysis for TFE3 was performed on 50 cases of SFTs that were surgically resected. The controls were sample tissues from malignant peripheral nerve sheath tumour, synovial sarcoma, dedifferentiated liposarcoma, spindle cell lipoma, and dermatofibrosarcoma protuberans. The survival of patients with TFE3-positive and TFE3-negative expressions was assessed through the Kaplan-Meier analysis. In 44 of 50 (88%) SFTs, nuclear immunoreactivity for TFE3 was detected. The TFE3 expression was negative in all samples of synovial sarcoma, malignant peripheral nerve sheath tumour, dermatofibrosarcoma protuberans, and spindle cell lipoma and weakly positive in 2 of 10 cases of dedifferentiated liposarcoma. Fluorescence in situ hybridization (FISH) confirmed that the expression of the TFE3 protein is not caused by gene translocation. There was no statistical significance between the association of the TFE3 expression and SFT patient prognosis. Therefore, TFE3 is capable of enhancing the differential diagnosis of SFTs and their histologic mimickers and can be potentially used as a diagnostic marker. The findings also offer valuable insights into SFT diagnosis, aetiology, and associated molecular mechanisms.

Giant Granular Cell Tumor of the Cervical Spinal Cord Resected via Anterior Corpectomy with Reconstruction: Technical Note and Review of Literature

BACKGROUND

Granular cell tumors (GCT) are rare soft tissue neoplasms with a nerve sheath origin, most often found in female adult populations. When these tumors arise in the central nervous system, they most commonly appear intradurally in the thoracic or lumbar spine. GCT malignancy rates vary and recurrence rates can be relatively high, thereby necessitating complete resection.

CASE DESCRIPTION

We present an exceedingly rare case of an intradural, extramedullary GCT originating in the anterior cervical spine of a male pediatric patient who presented with progressive neck pain and gait instability.

CONCLUSIONS

The patient underwent an anterior C7 corpectomy for resection of the tumor, followed by stabilization and fusion, and recovered without neurologic deficit. A literature review of spinal GCTs is provided.

Granular cell tumors overexpress TFE3 without gene rearrangement: Evaluation of immunohistochemistry and break-apart FISH in 45 cases

Transcription factor E3 (TFE3) is a useful marker for tumors with Xp11.2 translocation, including alveolar soft part sarcoma and renal cell carcinoma. Recently, TFE3 overexpression was also found in granular cell tumors (GrCTs). However, the case cohorts of these two studies were limited to only 11 and 6 cases. Whether aberrant TFE3 expression is a common feature of Asian patients with GrCT requires further investigation. In the present study, immunohistochemical staining and TFE3 break-apart fluorescence in situ hybridization (FISH) assay were performed in 45 samples of GrCTs obtained from Chinese patients recruited from three medical centers in northeast China. Diffusive and marked nuclear staining for TFE3 was identified in 11/45 (24%) cases, which was lower than previously reported. Focal or weak TFE3 staining was identified in 13/45 (29%) cases. The remaining 21 cases were negative stained. In addition, GrCTs in subcutaneous tissue exhibited a relatively higher ratio (8/45, 18%) for TFE3 expression, compared with those in other sites. Furthermore, according to FISH data, no rearrangement or amplification of TFE3 was identified in these cases, whether they were positively or negatively stained for TFE3. The results from the present study demonstrated that part of patients GrCTs exhibited TFE3 overexpression, which suggested that this may not be derived from gene rearrangement.

Xp11 translocation renal cell carcinoma and clear cell renal cell carcinoma with TFE3 strong positive immunostaining: morphology, immunohistochemistry, and FISH analysis

TFE3 is accepted as a good marker for the diagnosis of Xp11 translocation renal cell carcinoma. However, the significance of TFE3 in other types of renal cell carcinomas remains unclear. We examined the expression of TFE3 using immunohistochemistry by automated Ventana BenchMark XT system in 1818 consecutive renal cell carcinomas and verified the strong positive cases with TFE3 break-apart fluorescence in situ hybridization and RNA sequencing. Among the 27 renal cell carcinomas with TFE3 strong positive immunostaining, 20 cases were diagnosed as Xp11 translocation renal cell carcinoma, and seven cases were diagnosed as clear cell renal cell carcinoma. We further analyzed the morphology, clinicopathological features, and immunohistochemistry markers (CK7, CD117, CD10, P504s, vimentin, CA-IX, AE1/AE3, EMA, HMB45, Melan-A, and cathepsin K) of them. Pale to eosinophilic flocculent cytoplasm and psammomatous calcification were seen only in Xp11 translocation renal cell carcinomas (P < 0.05). Tumor necrosis occurred in all four cases of Xp11 translocation renal cell carcinomas with pT3a stage, which had local recurrence and distant metastasis (two of them died) within 3 years. The expressions of Vimentin, CA-IX, AE1/AE3, and EMA were significantly different between them (P < 0.05). CA-IX was diffusely strong positive in clear cell renal cell carcinomas but negative or focally mild positive in Xp11 translocation renal cell carcinomas. Our study first demonstrates that a very small minority (0.4%) of clear cell renal cell carcinomas with TFE3 strong positive immunostaining, which points out a potential pitfall in diagnosis of Xp11 translocation renal cell carcinomas by TFE3 immunohistochemistry. CA-IX is a good marker to distinguish clear cell renal cell carcinoma with TFE3 strong positive immunostaining from Xp11 translocation renal cell carcinoma. Tumor necrosis could be a potential factor relevant to pT3a stage, which may be a high-risk factor for the patients with Xp11 translocation renal cell carcinomas.

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.

[The histopathology and immunohistochemistry of granular cell tumour. A study of 12 cases with a brief historical note]

INTRODUCTION AND OBJECTIVE

Granular cell tumour (GCT) is a benign neoplasm of neural/schwannian origin, usually presenting as a single asymptomatic lesion, mainly located in the dermis and subcutaneous tissue or submucosa, although multiple tumours may occur. Microscopically, GCTs are composed of large cells with abundant eosinophilic, granular cytoplasm arranged in sheets, nests, cords or trabeculae. Based on the cytological characteristics and the presence of necrosis, three types are recognized: benign, atypical and malignant. We aim to present the cytological and immunohistochemical characteristics of 12 granular cell tumours.

MATERIALS AND METHODS

12 cases of GCT were selected from the consultation files of one of the authors (COH) The paraffin embedded tissue was processed for immunostaining with S-100 protein, calretinin, CD68, α-inhibin, PGP9.5, CD57 (Leu7), CD63 (NKI / C3), Gap43 (growth-associated protein-43), SOX10, TFE-3 and Ki-67.

RESULTS AND CONCLUSIONS

6 male and 6 female patients, with an average age of 40, made up the study group. The most frequent location for the tumours was in the subcutaneous soft tissues of the arms. There were no malignant cases. All tumours were positive for S-100, CD57, SOX10, calretinin, CD68, PGP9.5, α-inhibin and TFE-3, with a low Ki-67 (1-5%). Additionally, we reported, for the first time, the positive immunoreaction to Gap43 (growth-associated protein-43) in GCT.

Applications of Ancillary Testing in the Cytologic Diagnosis of Soft Tissue Neoplasms

Soft tissue neoplasms are diagnostically challenging, although many advances in ancillary testing now enable accurate classification of fine-needle aspiration biopsies by detection of characteristic immunophenotypes (including protein correlates of molecular alterations) and molecular features. Although there are many useful diagnostic immunohistochemical markers and molecular assays, their diagnostic utility relies on correlation with clinical and morphologic features, judicious application, and appropriate interpretation because no single test is perfectly sensitive or specific. This review discusses applications of ancillary testing for commonly encountered soft tissue neoplasms in cytopathologic practice in the context of a pattern-based approach.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Granular Cell Tumor of the Neurohypophysis With TFE-3 Expression: A Rare Case Report

Granular cell tumor (GCT) rarely involves the central nervous system, and fewer than 100 cases have been reported in English literatures. We herein report a case of a 36-year-old Chinese man with GCT of the neurohypophysis. Magnetic resonance imaging showed one mass located in the hypophysis with heterogeneous contrast enhancement. Pathological examination showed a neoplasm comprising densely packed polygonal cells of ample cytoplasm with abundant eosinophilic granules inside. The nuclei were small with inconspicuous nucleoli and yet without any mitoses. The tumor was positive for S-100, CD68, CD163, lysosome, and vimentin. Translocation factor E-3 (TFE-3) was diffusely nuclear positive although ASPSCR1-TFE-3 fusion was not detected by fluorescence in situ hybridization. GCT of the neurohypophysis is supposed to be considered under differential diagnosis with neoplasms or lesions of histiocytic origin and others such as pituitocytoma and spindle cell oncocytoma. A group of markers such as GFAP, EMA, CD68, S-100, and PAS staining are useful in complementary diagnosis and TFE-3 may be an alternative marker.

Alveolar Soft Part Sarcoma of the Female Genital Tract: A Morphologic, Immunohistochemical, and Molecular Cytogenetic Study of 10 Cases With Emphasis on its Distinction From Morphologic Mimics

Alveolar soft part sarcoma (ASPS) is a morphologically distinctive neoplasm of unknown differentiation that bears a characteristic gene fusion involving ASPSCR1 and TFE3. ASPS can occur in the female genital tract, but is rare. Eleven cases with an initial diagnosis of ASPS at female genital tract sites were evaluated for their morphologic features and immunoprofile using a panel of antibodies (TFE3, HMB45, melan-A, smooth muscle actin, desmin, and h-Caldesmon). In addition, the presence of TFE3 rearrangement and subsequent ASPSCR1-TFE3 fusion were determined by fluorescence in situ hybridization. Ten tumors retained their classification as ASPS based on their morphologic appearance, immunohistochemical profile, and demonstration of ASPSCR1-TFE3 fusion. The remaining case was reclassified as conventional-type PEComa due to its pattern of HMB45, melan-A, and desmin positivity as well as absence of TFE3 rearrangement. Sites of the 10 ASPS were uterine corpus (3), cervix (2), uterus not further specified (2), vagina (2), and vulva (1). The age of the patients ranged from 15 to 68 years (mean 34 y, median 32 y). The tumors demonstrated a spectrum of morphologic features, but all had a consistent immunophenotype of strong TFE3 nuclear expression and lack of muscle (smooth muscle actin, desmin, h-Caldesmon) and melanocytic (melan-A, HMB45) markers, except focal positivity for HMB45 in 1. Follow-up was available for 4 patients ranging from 1 to 35 months (mean 15 mo, median 25 mo) and they were alive and had no evidence of recurrence or metastasis at last follow-up. Distinguishing ASPS from its morphologic mimics, particularly PEComa, is important due to increasingly efficacious targeted agents such as MET-selective and VEGF signaling inhibitors in the former and mTOR inhibition therapy in the latter.