Correlation NKX2.2 IHC and EWSR1 break-apart FISH in the diagnosis of Ewing sarcoma: Can combined NKX2.2 and CD99 immunoexpression obviate or minimize the need of FISH testing? First assessment study from Indian tertiary cancer care center

Context: Ewing sarcoma (ES) are malignant small round cell tumors (MSRCT) characterized by rearrangements of EWSR1 gene. Although gold standard for diagnosis is detection of specific fusion genes by molecular testing, these ancillary tests are costly and only available in limited number of settings. There is a persuasive evidence for reliability of NKX2.2 immunohistochemistry (IHC) as a surrogate marker for EWSR1 gene rearrangement in ES. Aims: The aim of this study is to correlate the NKX2.2 immuno-expression with genetically confirmed ES cases and also to assess the reliability and accuracy of NKX2.2 along with combined positivity of NXX2.2 and CD99 in diagnosing ES and differentiating it from other relevant histological mimics. Settings and Design: The present study is a retrospective study conducted over a period of 6-year duration in a tertiary cancer care center. Methods and Material: We evaluated NKX2.2 immunoexpression in 35 genetically confirmed cases of ES and also in pertaining differential entities (n = 58) of ES including rhabdomyosarcoma (n = 20), lymphoblastic lymphoma (n = 14), Wilms tumor (n = 10), poorly differentiated synovial sarcoma (n = 4), small-cell osteosarcoma (n = 4), neuroblastoma (n = 5), and mesenchymal chondrosarcoma (n = 1). CD99 was performed in the category of MSRCTs showing NKX2.2 positivity to evaluate combined specificity for the diagnosis of ES. Results: Of the 35 genetically confirmed cases of ES, 29 cases (83%) showed NKX2.2-positive expression (83% sensitivity). Compared to ES, NKX2.2 was positive in only 05% cases (3/58 cases) of non-ES MSRCT. Only two of five cases of neuroblastomas and one case of mesenchymal chondrosarcoma showed NKX2.2 positivity. CD99 positivity was seen in 100% of ES and in the single case of mesenchymal chondrosarcoma. All five cases (100%) of neuroblastoma were negative for CD99. Conclusions: The presented study, which is the first from an Indian oncology center, showed NKX2.2 IHC is quite reliable in diagnosis of ES in the right clinicopathological context. With remarkable sensitivity and specificity of NKX2.2 IHC for diagnosis of ES, we propose that combined positivity of CD99 and NKX2.2 IHC can obviate or minimize the need of EWSR1 gene rearrangement molecular testing for diagnosis of ES.

Angiomatoid fibrous histiocytoma: Report of two cases, initially construed as sarcoma with unusual clinico-pathological features

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of uncertain differentiation with low metastatic potential, most commonly occurring in children, adolescents, and young adults, involving extremities. Due to its rare nature and diverse presentation, both clinically and morphologically, it is often misdiagnosed. It becomes important to correctly diagnose this lesion, given its distinct therapeutic implications. Here, we present the clinical, radiologic, and pathologic findings of two rare cases of AFH. Since AFH is a rare soft tissue tumor with low malignant potential, both pathologists and clinicians should be aware of this entity, when encountered with a soft tissue mass in extremities of a child or adolescent, so as to accord appropriate treatment in such cases.

A rare case of vulvar extraskeletal myxoid chondrosarcoma: mimics and diagnostic clues

Only 14 cases of extraskeletal myxoid chondrosarcoma (EMC) of the vulva have been documented in the literature. We report a case of a 63-year-old woman with EMC of the vulva confirmed by both EWSR1 and NR4A3 fluorescence in situ hybridization, the latter of which is a more specific probe for this entity. The unusual location of this tumor of prominent myxoid morphology gave rise to a wide differential diagnosis, which necessitated thorough histologic evaluation and confirmatory ancillary testing in the form of immunohistochemistry and cytogenetic studies. This article aims to review extraskeletal myxoid chondrosarcoma of the vulva and various diagnostic clues to help differentiate it from its histologic mimics. This is the fifth case of vulvar EMC in the literature with confirmation of a NR4A3 gene rearrangement.

Therapeutic targets of desmoplastic small round cell tumor and future direction / 中国肿瘤临床

Desmoplastic small round cell tumor (DSRCT) is a rare and highly malignant soft tissue sarcoma. Most patients are diagnosed at advanced stage unless DSRCT happens to be discovered accidentally. DSRCT mainly occurs in the abdomen and pelvis, spreading along the peritoneal surface. At the time of diagnosis, most patients have passed the operable stage. The diagnosis of DSRCT is based on the histological analysis of a biopsy. It typically manifests as small round blue cells in the nest, separated by a large number of fibroproliferative stroma. A stable cytogenetic feature of DSRCT is that the characteristic t(11; 22) (P13; Q12) chromosome produces the EWSWT1 fusion gene. The prognosis of patients with DSRCT is very poor, and the 5-year survival rate is about 15%. Despite the use of active treatment methods, such as chemotherapy, surgery, and total abdominal radiotherapy, about 60% 70% of patients with DSRCT die within 2- 3 years. Targeted therapy, immunotherapy, and other methods have been trialed recently in the treatment of DSRCT due to the development of DSRCT molecular genetics.

Hyalinizing clear cell carcinoma of the soft palate: a review of literature review

Hyalinizing clear cell carcinoma (HCCC), also known as clear cell carcinoma, not otherwise specified [CCC, (NOS)], is a rare minor salivary gland tumor characterized by proliferation of clear cells, organized in trabecular cords, or solid nests within loose to densely hyalinized stroma. It is considered a diagnosis of exclusion by the World Health Organization (WHO) because other salivary tumors may also have a clear cell component. Hence, there is a wide differential diagnosis. EWSR1-ATF1 gene rearrangements are fairly specific for this tumor, however, one of the recent studies have described its presence in clear cell odontogenic carcinoma (CCOC) one of its histologic mimickers. EWSR1 and CREM fusions have recently been described in these tumors but its importance is still not well described. Here we present a case of a 33-year-old woman who presented with a recurrent lesion of the soft palate. Her initial lesion was resected and diagnosed as low-grade myoepithelial tumor. Surgical margins at the time of initial resection were positive and the re-excision was recommended but the patient did not undergo surgery. Two years later, local recurrence at the same site was found and an excision was performed yielding negative margins. Histopathologic examination revealed features consistent with hyalinizing clear cell carcinoma. The patient remains disease free 1 year after the re-excision. The pathology, clinical characteristics, differential diagnosis and treatment of hyalinizing clear cell carcinoma are reviewed.

Clear cell sarcoma like tumor of gastrointestinal tract: Experience of three cases and review of literature

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSGT) is a rare, aggressive tumor with many histological mimickers. Herein, we have documented our experience of three cases of CCSGT and reviewed the literature. The index cases were identified in male patients in their twenties, one in jejunum and two in the distal colon. Histomorphological examination revealed the characteristic heterogeneous histomorphology with patchy immunohistochemical positivity with S100 protein and negative melanocytic markers. The fluorescence in-situ hybridization test showed translocation of the EWSR1 (22q12) gene in >80% tumor cells. While one of our patients died after 2 years with lung metastasis, the other two patients are still alive on 1.5 years and 3 months follow up, respectively. CCSGT is a rare malignant tumor of the gastrointestinal tract. Although characteristic morphology, use of a judicial panel of immunohistochemical stains, and translocation study for EWSR1 gene can establish the diagnosis, experience in adjuvant therapy is still limited.

Clinicopathologic and molecular characteristics of myxoid angiomatoid fibrous histiocytoma / 中华肿瘤杂志

Objective@#To investigate the molecular genetic and clinicopathologic characteristics, immunophenotypes, diagnostic and differential diagnostic features of myxoid angiomatoid fibrous histiocytoma (MAFH).@*Methods@#Three cases of MAFH were collected from the archives of Zhejiang Provincial People′s Hospital between January 2015 to August 2018. The clinical and radiologic features, histomorphology, immunohistochemistry, molecular genetics and prognosis were analyzed.@*Results@#Patients consisted of 2 women and 1 man aged 37 years, 46 years, and 57 years, respectively. The clinical manifestations of 3 patients were presented as a painless, slowly-enlarged mass with a duration ranging of 2 weeks, 2 months and 50 years. These tumors were located at the deep somatic soft tissue of extremities or limbs (right hip, left forearm, left wrist, respectively) and 2 were preoperatively considered as ganglion cyst or giant cell tumor of tendon sheath by imaging examinations. The diameter of circumscribed mass lesion was ranged from 3.0 to 7.5 cm, which exhibited a gray white to tan and gelatinous cut surface. Extensive hemorrhage and cystic changes were observed in 2 cases. Under low magnification, all tumors showed a dense fibrous pseudo-capsule with a peritumoral lymphoplasmacytic cuff and a multi-nodular growth pattern. Blood-filled cystic spaces were observed in 2 tumors. The myxoid stroma occupied 60.0%, 80.0% and 90.0% area of the entire tumor, respectively. Within the myxoid areas, tumor cells were oval to stellate and arranged in cord-like, microcystic and reticular growth patterns. Transitions of myxoid tumor components to more solid areas with typical histology of angiomatoid fibrous histiocytoma (AFH) were observed at least focally in all the three cases. The tumor cells exhibited minimal atypia and scarce mitoses (1 to 2/50 HPF) without necrosis, and prominently focal intracytoplasmic vacuoles were identified in one case. The results of immunohistochemistry staining showed that, 2/3 cases focally expressed desmin, 2/3 focally expressed epithelial membrane antigen (EMA), and 1/3 focally expressed CD99. The positive index of Ki67 was approximately 1% to 5%. Fluorescence in situ hybridization analysis showed that EWSR1 gene rearrangement occurred in all of the three cases. During the period of follow-up, one case showed local recurrence at 15 months, one case showed postoperative recurrence at 24 months, and the recurrent tumor slowly grew for 120 months until the second resection, without recurrence at the following 2 months. The left case showed a disease-free survival at 32 months.@*Conclusions@#MAFH is a rare subtype of AFH with a low-grade behavior and may lead to diagnostic confusions. Carefully searching for the typical AFH histomorphology and combining with EWSR1 gene rearrangement test can help to distinguish MAFH from other mimickers.

Genetic Ablation of EWS RNA Binding Protein 1 (EWSR1) Leads to Neuroanatomical Changes and Motor Dysfunction in Mice

A recent study reveals that missense mutations of EWSR1 are associated with neurodegenerative disorders such as amyotrophic lateral sclerosis, but the function of wild-type (WT) EWSR1 in the central nervous system (CNS) is not known yet. Herein, we investigated the neuroanatomical and motor function changes in Ewsr1 knock out (KO) mice. First, we quantified neuronal nucleus size in the motor cortex, dorsal striatum and hippocampus of three different groups: WT, heterozygous Ewsr1 KO (+/−), and homozygous Ewsr1 KO (−/−) mice. The neuronal nucleus size was significantly smaller in the motor cortex and striatum of homozygous Ewsr1 KO (−/−) mice than that of WT. In addition, in the hippocampus, the neuronal nucleus size was significantly smaller in both heterozygous Ewsr1 KO (+/−) and homozygous Ewsr1 KO (−/−) mice. We then assessed motor function of Ewsr1 KO (−/−) and WT mice by a tail suspension test. Both forelimb and hindlimb movements were significantly increased in Ewsr1 KO (−/−) mice. Lastly, we performed immunohistochemistry to examine the expression of TH, DARPP-32, and phosphorylated (p)-DARPP-32 (Thr75) in the striatum and substantia nigra, which are associated with dopaminergic signaling. The immunoreactivity of TH and DARPP-32 was decreased in Ewsr1 KO (−/−) mice. Together, our results suggest that EWSR1 plays a significant role in neuronal morphology, dopaminergic signaling pathways, and motor function in the CNS of mice.

Clinicopathologic analysis of primary pulmonary myxoid sarcoma with EWSR1 translocation / 中国癌症杂志

Background and purpose: Primary pulmonary myxoid sarcoma (PPMS) is a very rare lung tumor that has recently been shown to harbor EWSR1-CREB1 translocation. This study aimed to investigate the clinicopatho-logical characteristics and differential diagnosis of PPMS. Methods: The clinical and pathological features of 6 cases of PPMS with EWSR1 gene rearrangement were reviewed. Immunohistochemistry and fluorescence in situ hybridization (FISH) study were performed. Results: Six patients were enrolled in this study, including 4 male patients and 2 female patients with an age range of 23 to 64 years (median age, 44 years). All tumors involved pulmonary parenchyma, with a predominant endobronchial component in 1 and adjacent to bronchus in 5 patients. Microscopically, the tumor was lobulated and composed of cords of polygonal, spindle cells within myxoid stroma. Tumors were immunoreactive for only Vimentin and weakly focal for epithelial membrane antigen (EMA). All tumors were shown to harbor EWSR1 gene rearrangement by FISH. Follow-up of all patients showed that 1 patient developed a pleura and bone metastasis but was still alive and 5 were disease-free after 4-29 months. Conclusion: PPMS is an extremely rare sarcoma with low-grade malignant potential. This is characterized by distinct histological features and EWSR1 gene rearrangement. It is important that understanding tumor spectrum and genetic feature can contribute to diagnosis and differential diagnosis of PPMS.

Angiomatoid fibrous histiocytoma: Clinicopathological spectrum of five cases, including EWSR1‑CREB1 positive result in a single case.

Background: Angiomatoid fibrous histiocytoma (AFH) is an unusual soft tissue tumor (STT), characterized by recurrences, but rarely metastasis. Later, certain molecular signatures have been identified underlying this tumor, which at times, is either underdiagnosed as a benign vascular tumor, or over diagnosed as a high‑grade pleomorphic sarcoma, including a malignant fibrous histiocytoma. Materials and Methods: Over a 14‑year‑period, five diagnosed cases of AFH were analyzed. Results: Five tumors occurred in three males and two females, over a wide age‑range (median = 21, mean = 30 years); mostly in the extremities (4) (80%). Microscopically, most tumors were circumscribed, comprising large, blood‑filed spaces with surrounding histiocytic cells and a “cuff” of lymphoplasmacytic cells. Three tumors revealed solid growth pattern with polygonal to spindle cells, including myxoid matrix in one of these tumors. On molecular analysis, this tumor exhibited EWS‑CREB transcript. Immunohistochemically, various tumors were positive for CD68 (n = 2/2), epithelial membrane antigen (n = 3/4), CD99/MIC2 (n = 2/3), and desmin (n = 1/4). All tumors were surgically excised. On follow‑up (n = 2), a single patient, who underwent wide‑excision was free‑of‑disease (24 months), while another patient had a recurrence 4 months post tumor excision. Conclusions: This forms as the first documented series on clinicopathological features of AFH, a rare STT, from our country. Significant clinicopathological features include younger age, extremities as commonest site and histopathological appearance of blood‑filled spaces with surrounding “cuff” of histiocytic cells and lymphocytes. Tumors with unusual histopathological tumor patterns require molecular confirmation. Surgical resection remains the treatment mainstay.

Diagnosing A Rare Case Of Desmoplastic Small Round Cell Tumour On Liver Biopsy

A 50-year-old male of Indian descent presented with jaundice and right hypochondrium pain. Following a computed tomography (CT) scan of the abdomen, a segment 7 liver lesion was visualized, accompanied by extensive peritoneal tumour deposits. An ultrasound guided liver biopsy was performed and histology showed loose nests and sheets of tumour cells with a small blue round cell morphology. The tumour cells showed patchy strong immunopositivity for cytokeratins (AE1/3, CK7, CK19) and synaptophysin, while showing diffuse strong perinuclear positivity for desmin. Interphase fluorescence in-situ hybridization (FISH) study using EWSR1 breakapart probe was positive for EWSR1 gene rearrangement. Desmoplastic small round cell tumour is a rare but aggressive intra-abdominal mesenchymal tumour. While the primary sites of involvement are usually the peritoneum and omentum, visceral involvement can occur. We wish to highlight the importance of considering this entity when evaluating a liver biopsy especially in a less than classical clinical context.

Primary Ewing sarcoma of vulva, confirmed with molecular cytogenetic analysis: A rare case report with diagnostic and treatment implications.

Primary vulvar Ewing sarcoma (ES)/PNET is an uncommonly documented tumor, especially with molecular results. A 10-year-old girl presented with left vulvar swelling, a year ago. Her abdominopelvic ultrasound revealed a 12 cm × 8 cm sized, mixed echogenic blood-fi lled lesion in the left vulva; radiologically considered as a hematoma. Vulvectomy revealed a multinodular grey-brown tumor, microscopically comprising malignant round cells. Immunohistochemically, tumor cells diffusely expressed MIC2/ CD99 and Fli1 and subsequently displayed EWSR1 rearrangement, confi rming diagnosis of ES/PNET. Subsequently, PET-CT scan revealed residual local lesion with lung metastases. The patient was induced on EFT 2001 chemotherapy protocol. Three months after chemotherapy completion, there was no metabolically active disease on PET scan. Four months later, MRI disclosed recurrent primary and metastatic pulmonary lesions. She was planned for scar excision and adjuvant radiotherapy, but unfortunately defaulted further treatment. This forms the eighth case of primary vulvar ES/PNET confi rmed with molecular cytogenetic result, underscoring therapeutic value of objective diagnosis in such cases.

Detection of EWSR1 gene translocation in paraffin-embedded Ewing family tumor by fluores-cence in situ hybridization / 临床与实验病理学杂志

Purpose To evaluate the application of fluorescence in situ hybridization ( FISH) in detection of EWSR1 gene translocation in formalin-fixed paraffin-embedded tissue samples of Ewing family tumor ( EFT) . Methods Four cases of EFT were collected and their clinical pathological features were obsered. Interphase FISH was carried out in paraffin-embedded tissue of EFT cases, using a EWSR1 dual colar break-apart probe. Fifteen cases of other soft tissue tumor were selected as negative control. Results Translocation of EWSR1 was detected in four EFT cases, which may be a adjuvantly diagnositic value for the diagnosis of atypical cases. Conclu-sions FISH may serve as an adjunctive diagnostic tool in problematic cases of EFT, however, FISH results should be interpreted con-cerning clinical pathological features, morphological patterns and immunohistological results.

Peripheral Primitive Neuroectodermal Tumor with Osseous Component of the Small Bowel Mesentery: A Case Study

A case of peripheral primitive neuroectodermal tumor of the small bowel mesentery with osseous component is reported. A 23-year-old man was admitted to our hospital because of acute severe abdominal pain. Abdominal computed tomography revealed a large solid and cystic, oval shaped mass, measuring 11.0x6.0 cm in the pelvic cavity. Histologically the resected lesion consisted of sheets of undifferentiated small round cells forming Homer-Wright rosettes and perivascular pseudorosettes, and showed areas of osteoid and bone formation. Immunohistochemical studies revealed that tumor cells expressed positivity against CD99 (MIC2), CD57, neuron-specific enolase, and vimentin. Fluorescence in situ hybridization study revealed Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangement on chromosome 22q12. To the authors' knowledge this is the first documentation of a peripheral neuroectodermal tumor with osteoid and bone formation of the small bowel mesentery.