MED15::ATF1-Rearranged Tumor: A Novel Cutaneous Tumor With Melanocytic Differentiation

We recently described novel dermal tumors with melanocytic differentiation and morphologic and biological similarities to cutaneous clear cell sarcoma, including CRTC1::TRIM11 cutaneous tumor, and clear cell tumors with melanocytic differentiation and either ACTIN::MITF or MITF::CREM. Here, we describe a series of 3 patients presenting with tumors reminiscent of CRTC1::TRIM11 cutaneous tumor, found to demonstrate a novel MED15::ATF1 fusion. All 3 patients were children (5-16 years old). Primary excision of case 1 showed a circumscribed wedge-shaped silhouette with peripheral intercalation into collagen fibers and scattered lymphoid aggregates. All 3 tumors abutted the epidermis; one showed a junctional component. Tumors were highly cellular and comprised of monomorphic, oval-to-round epithelioid cells arranged in vague nests and short fascicles in variably fibrotic stroma. Mitotic rate was high (hotspot 6-12/mm2), without atypical mitoses. Necrosis was focally present in case 3. All cases showed strong, diffuse nuclear staining for SOX10 and MITF (2/2) but showed variable expression for S100 protein (1/3) and other melanocytic markers-Melan-A (focal in 2/3), HMB45 (focal in 1/3), and Pan-Melanoma (patchy in 1/1). Whole-exome RNA sequencing demonstrated a MED15::ATF1 fusion without any other notable alterations. Cases 1 and 2 were completely excised without recurrence (12 months). Case 3 developed a grossly apparent regional lymph node spread shortly after primary biopsy. The patient was treated with wide excision, radiation, cervical lymph node dissection (4/46 with >75% lymph node replacement), and neoadjuvant and adjuvant nivolumab (alive without disease at cycle 11). This series is presented to aid in future diagnosis of this novel dermal tumor with melanocytic differentiation and emphasize the potential for aggressive biologic behavior, which should be considered in patient management planning.

One step at a time: Melanocytic differentiation in fusion-driven cutaneous neoplasms

As dermatopathologists, we routinely diagnose melanocytic nevi, melanomas, and occasionally melanocytomas in our daily clinical practice. However, it is now clearly established that the presence of melanocytic differentiation in a tumor does not necessarily indicate any of the aforementioned diagnoses. Tumors such as clear cell sarcoma, malignant melanotic nerve sheath tumor, PEComa, melanotic neuroectodermic tumor of infancy, and even certain translocation-associated renal cell carcinomas all share the common characteristic of melanin synthesis. Over the past two decades, with the advent of molecular diagnostics, there has been an explosion of new data and discoveries in this field. Examples such as CRTC1::TRIM11 cutaneous tumors and MITF pathway-activated melanocytic tumors (ACTIN::MITF and MITF::CREM) have been incorporated into the latest edition of the WHO classification of skin tumors (5th ed). In a recent issue, Alexandrescu et al. reported another case of a dermal/subcutaneous melanocytic tumor harboring a MITF::CREM1 translocation. In a separate paper within the current issue, Li et al. present a case of clear cell sarcoma with the rare EWSR1::CREM fusion, which had initially been misdiagnosed as melanoma with regional and distant metastases. We warmly welcome these two very interesting and high-quality articles to our journal, and we eagerly anticipate what the future holds for this fascinating category of tumors.

Pediatric presacral tumors with intraspinal extension: a rare entity with diagnostic challenges

The presacral space is a potential space located between the rectum and the lumbosacral spine. It contains various primitive germ cell types that serve as the origin for a range of tumors. Imaging is crucial in characterizing, assessing the extent of and evaluating the treatment response to these tumors. We report a series of six cases of pediatric presacral tumors with intraspinal extension, including an immature sacrococcygeal teratoma (Altman type II), a malignant sacrococcygeal teratoma (Altman type IV), a neuroblastoma, a rhabdomyosarcoma, a clear cell sarcoma and an Ewing's sarcoma of the ilium. These tumors can be broadly categorized as tumors of germ cell, neuroblastic, mesenchymal and osteogenic origin. Despite overlapping imaging features, a review of the existing literature and careful retrospective observation revealed several distinctive features that aid in the optimal characterization of tumors. These include the tumor's epicenter, the pattern and degree of bone involvement, the status of sacral foramina and neural elements, and internal tumor characteristics such as the presence of fat, calcification, hemorrhage and necrosis.

A Rare Case of Clear Cell Sarcoma of the Tongue: A Case Report

Clear cell sarcoma (CCS), previously known as soft tissue melanoma due to similarities with melanoma, is a rare and aggressive neoplasm. This tumor predominantly occurs in the lower limbs and rarely affects the tongue, as well as other head and neck locations. To our knowledge, only five cases have been reported in the English literature. CCS presents many similar morphological and immunohistochemical features to those of melanomas, sarcomatoid cell carcinoma, angiomatoid histiocytoma, and Ewing sarcoma, which makes the diagnosis difficult, especially in cases of uncommon locations. The treatment is based on oncological surgery and adjuvant radiation therapy as these tumors show low sensitivity to chemotherapy. This study aimed to report a case of an 88-year-old male patient who presented a large, rapidly growing nodular lesion on the right border of the mobile tongue diagnosed with CCS of the tongue.

The current management of clear cell sarcoma

Clear cell sarcoma (CCS) is a rare melanocytic soft tissue sarcoma with a high propensity for lymphatic metastasis and poor prognosis. It is characterized by the translocation of t (12;22), resulting in the rearrangement of the EWSR1 gene and overexpression of MET. Despite improvements in the diagnosis and treatment of soft tissue sarcomas, the management of CCSs remains challenging owing to their rarity, unique biological behaviour and limited understanding of their molecular pathogenesis. The standard treatment for localized CCSs is surgical excision with negative margins. However, there is an ongoing debate regarding the role of adjuvant chemotherapy, radiotherapy and lymphadenectomy in the management of this disease. CCSs are usually resistant to conventional chemotherapy. Targeted therapies, such as sunitinib and MET inhibitors, may provide promising results. Immunotherapy, particularly immune checkpoint inhibitors, is currently under investigation as a potential treatment option for CCSs. Further research is needed to better understand the biology of CCSs and develop effective therapeutic strategies. The purpose of this review is to provide a comprehensive overview of current knowledge and advances in the diagnosis and treatment of CCSs.

Children's Oncology Group's 2023 blueprint for research: Renal tumors

Every year, approximately 600 infants, children, and adolescents are diagnosed with renal cancer in the United States. In addition to Wilms tumor (WT), which accounts for about 80% of all pediatric renal cancers, clear cell sarcoma of the kidney, renal cell carcinoma, malignant rhabdoid tumor, as well as more rare cancers (other sarcomas, rare carcinomas, lymphoma) and benign tumors can originate within the kidney. WT itself can be divided into favorable histology (FHWT), with a 5-year overall survival (OS) exceeding 90%, and anaplastic histology, with 4-year OS of 73.7%. Outcomes of the other pediatric renal cancers include clear cell sarcoma (5-year OS: 90%), malignant rhabdoid tumor (5-year OS: 10% for stages 3 and 4), and renal cell carcinoma (4-year OS: 84.8%). Recent clinical trials have identified novel biological prognostic markers for FHWT, and a series of Children's Oncology Group (COG) trials have demonstrated improving outcomes with therapy modification, and opportunities for further care refinement.

Clear cell tumor with melanocytic differentiation and MITF::CREM translocation

In addition to melanoma, a large and diverse family of tumors shows melanocytic differentiation. The best characterized member of this family is clear cell sarcoma, which is characterized by EWSR1::ATF1 and EWSR1::CREB1 fusions. These fusions drive the transcription of MITF, the master regulator of melanocytic differentiation. Clear cell tumor with melanocytic differentiation and MITF::CREM translocation is a recently described tumor with some similarities to clear cell sarcoma. However, only a single case has been reported. Here, we describe a second molecularly proven case that arose on the scalp of a newborn baby. In contrast to the prior reported case, the current case showed predominantly high-grade cytomorphologic features with only focal clear cell areas. Similar to the prior case, the tumor showed immunohistochemical evidence of neural crest origin/differentiation with prominent melanocytic differentiation. The fusion breakpoints were also similar and preserved the transcriptional activation domain of CREM, suggesting that CREM hyperactivity is a major feature of this tumor type. The current tumor showed a short-interval recurrence. These results expand the clinical and pathologic spectrum of this potentially new entity.

"E-MGNET": Extra-Enteric Malignant Gastrointestinal Neuroectodermal Tumor- A Clinicopathological and Molecular Genetic Study of 11 Cases

Malignant gastrointestinal neuroectodermal tumors (MGNET), also known as "gastrointestinal clear cell sarcoma-like tumor", are very rare, aggressive sarcomas characterized by enteric location, distinctive pathologic features, and EWSR1/FUS::ATF1/CREB1 fusions. Despite identical genetics, the clinicopathologic features of MGNET are otherwise quite different from clear cell sarcoma of soft parts (CCS). Only exceptional extra-enteric MGNET (E-MGNET) have been reported. We report a series of 11 E-MGNET, the largest to date. Cases diagnosed as MGNET and occurring in non-intestinal locations were retrieved. Clinical follow-up was obtained. The tumors occurred in 3 males and 8 females (14-70 years of age, median 33 years) and involved the soft tissues of the neck (3), shoulder (1), buttock (2), orbit (1), and tongue/parapharyngeal space (1), the urinary bladder (1) and the falciform ligament/liver (1). Tumors showed morphologic features of enteric MGNET (small, relatively uniform, round to ovoid cells with round, regular nuclei containing small nucleoli, growing in multinodular and vaguely lobular patterns, with solid, pseudoalveolar and pseudopapillary architecture). Immunohistochemical results were: S100 protein (11/11), SOX10 (11/11), synaptophysin (3/10), CD56 (7/9), CD117 (3/9), DOG1 (0/4), ALK (4/8), chromogranin A (0/10), HMB45 (0/11), Melan-A (0/11), tyrosinase (0/4), MiTF (0/11). NGS results were: EWSR1::ATF1 (7 cases), EWSR1::CREB1 (3 cases) and EWSR1::PBX1 (1 case). The EWSR1::PBX1-positive tumor was similar to other cases, including osteoclast-like giant cells, and negative for myoepithelial markers. Clinical follow-up (range: 10 to 70 months; median 34 months) showed 4 patients dead of disease (10.5, 12, 25 and 64 months after diagnosis), 1 patient alive with extensive metastases (43 months after diagnosis), 1 patient alive with persistent local disease (11 months after diagnosis), and 4 alive without disease (10, 47, 53 and 70 months after diagnosis). One case is too recent for follow-up. The clinicopathologic and molecular genetic features of rare E-MGNET are essentially identical to those occurring in intestinal locations. Otherwise-typical E-MGNET may harbor EWSR1::PBX1, a finding previously unreported in this tumor type. As in enteric locations, the behavior of E-MGNET is aggressive, with metastases and/or death from disease in at least 50% of patients. E-MGNET should be distinguished from CCS and other tumors with similar fusions. ALK expression appears to be a common feature of tumors harboring EWSR1/FUS::ATF1/CREB1 fusion but is unlikely to predict therapeutic response to ALK inhibition. Future advances in our understanding of these unusual tumors will hopefully lead to improved nomenclature.

Multiple metastases of clear cell sarcoma at diagnosis presented in bone marrow aspirate: A case report

Clear cell sarcoma (CCS) is a rare and aggressive soft-tissue sarcoma that arises most commonly in adolescents and young adults of both sexes. CCS presents a diagnostic challenge due to its morphological and immunohistochemical similarity to malignant melanoma. We present a rare and severe case of CCS simultaneously with multiple bone and lymph node metastases at the time of initial diagnosis in a previously healthy 15-year-old Chinese man. Detailed information on clinical manifestations, laboratory profiles, histopathological findings and poor outcome were described. The cytomorphology of bone marrow aspirate in CCS in Wright-Giemsa staining smear was first depicted in this case. The diagnostic difficulties of the rare case was also discussed.

PRAME is a useful marker for the differential diagnosis of melanocytic tumours and histological mimics

AIMS

Although the morphological assessment of melanoma is generally straightforward, diagnosis can be especially difficult when the significant morphological and immunohistochemical results overlap with those of benign and malignant melanocytic tumours and histological mimics. This study assessed the potential diagnostic utility of measuring PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemically in naevi, melanomas and clear cell sarcomas (CCSs) in Chinese patients.

METHODS

We examined the immunohistochemical expression of PRAME in 317 melanocytic naevi, 178 primary melanomas, 72 metastatic melanomas and 19 CCSs and compared the sensitivity and specificity of PRAME immunohistochemistry (IHC) in the differential diagnosis of melanocytic tumours and histological mimics.

RESULTS

Of the 317 melanocytic naevi, 98.1%were completely negative for PRAME; six cases showed focal PRAME immunoreactivity in a minor population of lesional melanocytes. Diffuse nuclear immunoreactivity for PRAME was found in 89.9% of primary melanomas and 93.1% of metastatic melanomas. Regarding melanoma subtypes, PRAME was expressed in 100% of superficial spreading melanomas, 100% of melanomas arise in congenital naevus, 91.4% of nodular melanomas, 87.8% of acral lentigo melanomas, 80.0% of lentigo malignant melanomas, 60.0% of Spitz melanomas, 96.2% of mucosal melanomas and 80.0% of uveal melanomas. None of the two desmoplastic melanomas expressed PRAME. Of the 19 CCS cases, 89.5% were negative for PRAME and 10.5% showed focal weak PRAME immunoreactivity in a minor population of tumour cells.

CONCLUSIONS

Our findings indicate that PRAME may be a useful marker to support a suspected diagnosis of melanoma. In addition, lack of PRAME expression is a valuable hint to CCS in a suspected case, and then molecular confirmation of the presence of EWSR1 rearrangement is necessary.

Clear cell sarcoma of soft tissue with plasmacytoid morphology: A rare case report

RATIONALE

Clear cell sarcoma of soft tissue (CCSST) is a rare malignant tumor that occurs in the extremities of young adults. CCSST has been documented to have atypical histopathological features, such as epidermotropism or myxoid differentiation, which may set pitfalls in the differential diagnosis. We report a case of CCSST with plasmacytoid morphology which has never been described.

PATIENT CONCERNS

A 15-year-old male, presented with a 5-cm mass in his left inguinal area.

DIAGNOSIS

Positron emission tomography-computed tomography examination showed nodules in the left groin and the lung, the latter was considered metastasis. A core needle biopsy with the diagnosis of CCSST with plasmacytoid morphology was made according to histology, immunostaining, and molecular analysis.

INTERVENTIONS

The patient received chemotherapy of doxorubicin and ifosfamide.

OUTCOMES

The patient failed to respond to the standard chemotherapy and deceased twelve months after diagnosis.

LESSONS

This special case of CCSST with plasmacytoid features demonstrated a morphological variation never been documented and may easily lead to misdiagnosis. For such cases, molecular analysis is essential to provide solid evidence for accurate diagnosis.

Clear-Cell Sarcoma With an Unusual Presentation Mimicking Metastatic Melanoma

Clear-cell sarcoma (CCS) was first described in 1968. It partly overlaps morphologically, immunohistochemically, and ultrastructurally with malignant melanoma (MM), hence its name "soft tissue melanoma." Nevertheless, there are sufficient cytogenetic differences between cutaneous melanoma and clear-cell sarcoma to consider clear-cell sarcoma as a separate entity. Clear-cell sarcoma of soft tissue is different from clear-cell sarcoma of the kidney. It is classified as a tumor of uncertain differentiation in the WHO 2020 classification of soft tissue tumors. It is an aggressive, rare malignant tumor that is involved in the deep soft tissues of the extremities and trunk. We report a case of primary clear-cell sarcoma of unusual presentation in a 31-year-old young man, mimicking metastatic melanoma. A 31-year-old man presented with a heel mass of 2.5 cm. Histologically, it was a dermal and hypodermal nodular proliferation of spindle cells of 23 mm with a grenz zone under the epidermis. There was no necrosis area or lymphovascular invasion. Surgical margins were free. There were no clinically suspicious lymph nodes. The tumor cells were stained for S100 protein, MELAN A, and HMB45, which led to an initial diagnosis of metastatic malignant melanoma. However, analysis by fluorescence in situ hybridization (FISH) found a rearrangement of the Ewing sarcoma region 1 (EWSR1) gene, which led to a diagnosis of primary clear cell sarcoma in the skin. This case highlights the importance of considering the diagnosis of a clear-cell sarcoma in front of any dermal lesions with morphological and immunohistochemical melanocytic features that do not have an in situ component and of atypical presentation, especially in young patients, hence the interest in performing fluorescence in situ hybridization for EWSR1, which remains the key to the diagnosis of cutaneous clear-cell sarcoma.

Protein arginine methyltransferase 5 is essential for oncogene product EWSR1-ATF1-mediated gene transcription in clear cell sarcoma

Transcription dysregulation is common in sarcomas driven by oncogenic transcription factors. Clear cell sarcoma of soft tissue (CCSST) is a rare sarcoma with poor prognosis presently with no therapy. It is characterized by a balanced t(12;22) (q13;q12) chromosomal translocation, resulting in a fusion of the Ewing's sarcoma gene EWSR1 with activating transcription factor 1 (ATF1) to give an oncogene EWSR1-ATF1. Unlike normal ATF1, whose transcription activity is dependent on phosphorylation, EWSR1-ATF1 is constitutively active to drive ATF1-dependent gene transcription to cause tumorigenesis. No EWSR1-ATF1-targeted therapies have been identified due to the challenges in targeting intracellular transcription factors. Through proteomics screening to identify potential druggable targets for CCSST, we discovered protein arginine methyltransferase 5 (PRMT5) as a novel protein to interact with EWSR1-ATF1. PRMT5 is a type II protein arginine methyltransferase to symmetrically dimethylate arginine residues in substrate proteins to regulate a diverse range of activities including gene transcription, RNA splicing, and DNA repair. We found that PRMT5 enhances EWSR1-ATF1-mediated gene transcription to sustain CCSST cell proliferation. Genetic silencing of PRMT5 in CCSST cells resulted in severely impaired cell proliferation and EWSR1-ATF1-driven transcription. Furthermore, we demonstrate that the clinical-stage PRMT5 inhibitor JNJ-64619178 potently and efficaciously inhibited CCSST cell growth in vitro and in vivo. These results provide new insights into PRMT5 as a transcription regulator and warrant JNJ-64619178 for further clinical development to treat CCSST patients.

Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion and prominent epidermal involvement: A case report

Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMCT) is a recently described entity with only 13 cases reported in the literature. Histopathologically, the neoplasm consists of atypical epithelioid to spindled cells that form a well-circumscribed nodule confined to the dermis and subcutis with cytological features including large vesicular nuclei with prominent nucleoli and abundant eosinophilic cytoplasm. Immunohistochemistry shows variable expressivity of melanocytic markers. Currently, there is limited data regarding long-term outcomes of this newly described entity. Most cases have done well, but there is one case reported with an adverse event. Hence, further studies are needed to accurately classify this tumor. Definitive diagnosis is made by laboratory evidence of CRTC1::TRIM11 fusion. Herein, we report the first case of CMCT with epidermal involvement in the youngest patient known to be affected to date.

Systemic treatment of advanced clear cell sarcoma: results from a retrospective international series from the World Sarcoma Network

Background

Clear cell sarcoma (CCS) is a translocated aggressive malignancy with a high incidence of metastases and poor prognosis. There are few studies describing the activity of systemic therapy in CCS. We report a multi-institutional retrospective study of the outcomes of patients with advanced CCS treated with systemic therapy within the World Sarcoma Network (WSN).

Materials and methods

Patients with molecularly confirmed locally advanced or metastatic CCS treated with systemic therapy from June 1985 to May 2021 were included. Baseline demographic and treatment information, including response by Response Evaluation Criteria in Solid Tumours (RECIST) 1.1, was retrospectively collected by local investigators. Descriptive statistics were carried out.

Results

Fifty-five patients from 10 institutions were included. At diagnosis, the median age was 30 (15-73) years and 24% (n = 13/55) had metastatic disease. The median age at diagnosis was 30 (15-73) years. Most primary tumours were at aponeurosis (n = 9/55, 16%) or non-aponeurosis limb sites (n = 17/55, 31%). The most common fusion was EWSR1–ATF1 (n = 24/55, 44%). The median number of systemic therapies was 1 (range 1-7). The best response rate was seen for patients treated with sunitinib (30%, n = 3/10), with a median progression-free survival of 4 [95% confidence interval (CI) 1-7] months. The median overall survival for patients with advanced/metastatic disease was 15 months (95% CI 3-27 months).

Conclusions

Soft tissue sarcoma-type systemic therapies have limited benefit in advanced CCS and response rate was poor. International, multicentre prospective translational studies are required to identify new treatments for this ultra-rare subtype, and access to early clinical trial enrolment remains key for patients with CCS.

•

This is the largest reported series of advanced CCS patients treated with systemic therapy.

•

The activity of sarcoma-type systemic therapy is poor and modest responses were seen only with sunitinib.

•

Effective therapies are needed to improve outcomes for patients with this ultra-rare sarcoma type.

Trends of lymph node sampling and metastasis in pediatric and young adult patients with clear cell, epithelioid, and synovial sarcomas

BACKGROUND

Clear cell sarcoma of soft tissue (CCS), epithelioid sarcoma, and synovial sarcoma are rare tumors historically identified as high risk for lymph node metastasis. This study investigates incident nodal metastasis and associated survival in children and young adults with these subtypes.

PROCEDURE

Using the National Cancer Database (2004-2015), we created a retrospective cohort of 1303 patients (aged ≤25 years) who underwent local control therapy for CCS, epithelioid sarcoma, and synovial sarcoma. Kaplan-Meier curves estimated overall survival (OS) by subtype. Stratifying on subtype, Cox regressions assessed OS by lymph node sampling status and nodal metastasis.

RESULTS

There were 103 (7.9%) patients with CCS, 221 (17.0%) with epithelioid sarcoma, and 979 (75.1%) with synovial sarcoma. Lymph node sampling was more frequent in patients with CCS (56.3%) and epithelioid sarcoma (52.5%) versus synovial sarcoma (20.5%, p < .001). Synovial sarcoma metastasized to lymph nodes less frequently than CCS or epithelioid sarcoma (2.1% vs. 14.6% and 14.9%, p < .001). Across all subtypes, lymph node metastasis was associated with inferior OS (HR 2.02, CI 1.38-2.95, p < .001). Lymph node sampling was associated with improved OS in CCS (HR 0.35, CI: 0.15-0.78, p = .010), inferior OS in synovial sarcoma (HR 1.60, CI: 1.13-2.25, p = .007), and no statistical association with OS in epithelioid sarcoma.

CONCLUSIONS

Lymph node metastasis is rare in children and young adults with synovial sarcoma. Lymph node sampling procedures were not consistently performed for patients with CCS or epithelioid sarcoma, but improved OS supports routine lymph node sampling in children and young adults with CCS.

Nevus, melanoma or something else? Mesenchymal neoplasms with melanocytic differentiation

The overwhelming majority of cutaneous neoplasms with melanocytic differentiation are nevi, melanomas and more rarely melanocytomas. Nevertheless, there is also a group of mesenchymal neoplasms with genuine melanocytic differentiation which can create diagnostic difficulties with significant repercussions. These can rarely present as primary or metastatic cutaneous lesions. Theones that are relevant to a dermatopathologist include malignant melanotic nerve sheath tumor, perivascular epithelioid cell neoplasm and clear cell sarcoma. This work will provide a thorough review of clinical presentation, morphologic and immunohistochemical features as well as molecular pathogenesis of these tumors. We hope to familiarize the general dermatopathology readership with a group of neoplasms of mesenchymal lineage exhibiting melanocytic differentiation and ultimately avoid diagnostic misadventures. This article is protected by copyright. All rights reserved.

Case report: Robust response of metastatic clear cell sarcoma treated with cabozantinib and immunotherapy

Clear Cell Sarcoma (CCS), also referred to as malignant melanoma of soft parts, is a rare and aggressive malignant tumor. It comprises 1% of all soft tissue sarcomas and is known to be radio- and chemotherapy resistant. CCS shares morphological and immunohistochemical features with malignant melanoma, including melanin biosynthesis and melanocytic markers. However, it is distinct for the presence of EWSR1-ATF1 translocation which activates MITF transcription factor. We report here of an aggressive case of CCS in a 9-year-old patient, which demonstrates the critical role of molecular analysis in the diagnosis and treatment of uncommon cancer variants in the era of personalized medicine. The EWSR1-ATF1 translocation induces pathological c-Met activation, and so, following unsuccessful CTLA4 and PD-1 blockade immunotherapy, the child received cabozantinib, a small molecule tyrosine kinase inhibitor, with the intent to block c-Met oncogenic effect. In parallel, active immunization, using hapten di-nitrophenyl modified autologous tumor cells was administered with monotherapy PD-1 inhibitor nivolumab. Under this "triplet" therapy, the patient attained an initial partial response and was progression-free for 2 years, in good performance status and resumed schooling. Based on our observation, cabozantinib can be used as an effective and potentially life-prolonging treatment in CCS. We suggest that priming the child's immune system using her autologous tumor and combating T cell exhaustion with PD-1 blockade may have synergized with the targeted therapy. Combining targeted and immunotherapy is a rapidly growing practice in solid tumors and provides a glimpse of hope in situations that previously lacked any treatment option.

Clinical Experience with Apatinib and Camrelizumab in Advance Clear Cell Sarcoma: A Retrospective Study

Purpose

Advanced clear cell sarcoma (CCS) is a rare subtype of sarcoma with few effective treatments. Evidence shows that apatinib is efficacious and safe for CCS. This study aimed to assess the safety and efficacy of apatinib and/or camrelizumab (a PD-1 inhibitor) in treating advanced CCS.

Methods

We retrospectively reviewed 12 patients with advanced CCS who received apatinib and/or camrelizumab therapy between November 2018 and July 2021. Standard descriptive statistics were employed for continuous variables and categorical variables (number and percentage).

Results

Of the 12 CCS patients, 3 had a partial response (PR), and 4 had stable disease (SD). Among the 5 patients treated with apatinib monotherapy, 1 PR and 2 SD were found, and the addition or replacement of camrelizumab after progressive disease (PD) did not work. In the 4 patients who received apatinib plus camrelizumab combination therapy, 1 PR and 1 SD were found. All 3 patients who received camrelizumab first had PD, and 1 PR and 1 SD were found after adding apatinib. Grade 3 or 4 adverse events were significantly more common in the apatinib plus camrelizumab combination therapy than in the apatinib or camrelizumab monotherapy, and these included increased aspartate aminotransferase and increased alanine aminotransferase levels.

Conclusion

Apatinib has promising effectiveness for CCS. Camrelizumab efficacy for the treatment of clear cell sarcoma is inconclusive. The efficacy of apatinib and PD-1 inhibitors in CCS need to be further investigated in prospective clinical trials.

Histopathological and Molecular Profiling of Clear Cell Sarcoma and Correlation with Response to Crizotinib: An Exploratory Study Related to EORTC 90101 "CREATE" Trial

Simple Summary

Clear cell sarcoma (CCSA) is a rare subtype of soft tissue sarcoma characterized by EWSR1 rearrangement and subsequent MET upregulation. The European Organisation for Research and Treatment of Cancer 90101 phase II trial evaluated the MET inhibitor crizotinib in CCSA but resulted in only sporadic responses. The aim of this exploratory study was to identify the molecular alterations potentially relevant for the treatment outcome by using archival CCSA samples and trial-related clinical data. We characterized MET signaling and revealed an infrequent activation of MET, which may explain the lack of response to crizotinib in the disease cohort. Based on sequencing analyses, we discovered copy number alterations, mutations and dysregulated pathways with potentially predictive or prognostic values for patients’ outcomes. This work describes the molecular heterogeneity in CCSA and provides deep insight into the biology of this ultra-rare malignancy, which may potentially lead to better therapeutic approaches.

Abstract

Clear cell sarcoma (CCSA) is characterized by a chromosomal translocation leading to EWSR1 rearrangement, resulting in aberrant transcription of multiple genes, including MET. The EORTC 90101 phase II trial evaluated the MET inhibitor crizotinib in CCSA but resulted in only sporadic responses. We performed an in-depth histopathological and molecular analysis of archival CCSA samples to identify alterations potentially relevant for the treatment outcome. Immunohistochemical characterization of MET signaling was performed using a tissue microarray constructed from 32 CCSA cases. The DNA from 24 available tumor specimens was analyzed by low-coverage whole-genome sequencing and whole-exome sequencing for the detection of recurrent copy number alterations (CNAs) and mutations. A pathway enrichment analysis was performed to identify the pathways relevant for CCSA tumorigenesis. Kaplan–Meier estimates and Fisher’s exact test were used to correlate the molecular findings with the clinical features related to crizotinib treatment, aiming to assess a potential association with the outcomes. The histopathological analysis showed the absence of a MET ligand and MET activation, with the presence of MET itself in most of cases. However, the expression/activation of MET downstream molecules was frequently observed, suggesting the role of other receptors in CCSA signal transduction. Using sequencing, we detected a number of CNAs at the chromosomal arm and region levels. The most common alteration was a gain of 8q24.21, observed in 83% of the cases. The loss of chromosomes 9q and 12q24 was associated with shorter survival. Based on exome sequencing, 40 cancer-associated genes were found to be mutated in more than one sample, with SRGAP3 and KMT2D as the most common alterations (each in four cases). The mutated genes encoded proteins were mainly involved in receptor tyrosine kinase signaling, polymerase-II transcription, DNA damage repair, SUMOylation and chromatin organization. Disruption in chromatin organization was correlated with longer progression-free survival in patients receiving crizotinib. Conclusions: The infrequent activation of MET may explain the lack of response to crizotinib observed in the majority of cases in the clinical trial. Our work describes the molecular heterogeneity in CCSA and provides further insight into the biology of this ultra-rare malignancy, which may potentially lead to better therapeutic approaches for CCSA.

Intracranial mesenchymal tumors with FET-CREB fusion are composed of at least two epigenetic subgroups distinct from meningioma and extracranial sarcomas

‘Intracranial mesenchymal tumor, FET‐CREB fusion‐positive’ occurs primarily in children and young adults and has previously been termed intracranial angiomatoid fibrous histiocytoma (AFH) or intracranial myxoid mesenchymal tumor (IMMT). Here we performed genome‐wide DNA methylation array profiling of 20 primary intracranial mesenchymal tumors with FET‐CREB fusion to further study their ontology. These tumors resolved into two distinct epigenetic subgroups that were both divergent from all other analyzed intracranial neoplasms and soft tissue sarcomas, including meningioma, clear cell sarcoma of soft tissue (CCS), and AFH of extracranial soft tissue. The first subgroup (Group A, 16 tumors) clustered nearest to but independent of solitary fibrous tumor and AFH of extracranial soft tissue, whereas the second epigenetic subgroup (Group B, 4 tumors) clustered nearest to but independent of CCS and also lacked expression of melanocytic markers (HMB45, Melan A, or MITF) characteristic of CCS. Group A tumors most often occurred in adolescence or early adulthood, arose throughout the neuroaxis, and contained mostly EWSR1‐ATF1 and EWSR1‐CREB1 fusions. Group B tumors arose most often in early childhood, were located along the cerebral convexities or spinal cord, and demonstrated an enrichment for tumors with CREM as the fusion partner (either EWSR1‐CREM or FUS‐CREM). Group A tumors more often demonstrated stellate/spindle cell morphology and hemangioma‐like vasculature, whereas Group B tumors more often demonstrated round cell or epithelioid/rhabdoid morphology without hemangioma‐like vasculature, although robust comparison of these clinical and histologic features requires future study. Patients with Group B tumors had inferior progression‐free survival relative to Group A tumors (median 4.5 vs. 49 months, p = 0.001). Together, these findings confirm that intracranial AFH‐like neoplasms and IMMT represent histologic variants of a single tumor type (‘intracranial mesenchymal tumor, FET‐CREB fusion‐positive’) that is distinct from meningioma and extracranial sarcomas. Additionally, epigenomic evaluation may provide important prognostic subtyping for this unique tumor entity.

Clear cell carcinoma: a comprehensive literature review of 254 cases

This comprehensive literature review represents a summary of all cases of clear cell carcinoma (CCC) of the salivary glands that are documented in the literature. PubMed was used to collect available reports of CCC; 97 reports detailing 254 cases, published between 1983 and 2020, were retrieved. Clinically the tumor manifests most commonly as a painless mass or swelling on the palate, and the duration of symptoms prior to seeking care ranges from 1 week to 6 years. Local tumor recurrence was present in 18.8% of the cases. By histopathology, CCC shows a mixture of growth patterns including solid (25.1%), nested (78.6%), sheet-like (23.5%), cords (46.1%), and trabeculae (42.4%). Immunohistochemical studies are positive for one or more cytokeratins (99.1%), PAS (95.1%), EMA (77.8%), and p63 (96.3%), but negative for S-100 (96.3%), PASD (91.1%), SMA (91.0%), and calponin (95.1%). Molecular features were reported in 113 cases; 96.0% were positive for an EWSR1 rearrangement by EWSR1 break apart FISH testing and 14.8% were positive for the rearrangement EWSR1-ATF1 tested by qPCR or targeted RNA sequencing. Clinical patterns and genetic studies imply that this tumor is the extraosseous counterpart of clear cell odontogenic carcinoma, an intraosseous odontogenic tumor of the jaws.

Clear Cell Sarcoma of the Achilles Tendon: A Case Report

Clear cell sarcoma of the Achilles tendon is an extremely rare condition, with a handful of cases reported in the literature over the past 3 decades. Patients usually present late because of the slow progress of the disease and seemingly benign nature of its presentation. Clinical and radiological findings are not enough to make a diagnosis; hence, a high index of suspicion is required. A firm diagnosis is made only after histopathologic studies. We present a rare case of this tumor in a young female, the management plan, and prognostic outlook, with subsequent review of the literature.

A report of three cases]

The paper describes three cases of soft tissue clear cell sarcoma, a rare melanin-producing malignant tumor, which is diagnosed in 52-to-87-year-old women. It provides a clinical and morphological description of the tumor and the results of immunohistochemical tests.

Pathologic nodal staging for clinically node negative soft tissue sarcoma of the extremities

BACKGROUND AND OBJECTIVES

Synovial, clear cell, angiosarcoma, rhabdomyosarcoma, and epithelioid (SCARE) soft tissue sarcoma are at risk for nodal involvement, although the nodal positivity rates and impact on prognostication in clinically node negative patients are not well described.

METHODS

Patients with extremity SCARE sarcoma without clinical nodal involvement undergoing surgical resection in the National Cancer Database (2004-2017) were included. Logistic regression was used to evaluate the likelihood of nodal surgery and nodal positivity. Kaplan-Meier method and Cox regression were used to assess associations of nodal status to overall survival.

RESULTS

We included 4158 patients, and 669 patients (16%) underwent regional lymph node surgery (RLNS). On multivariable logistic analysis, patients with epithelioid (odds ratio [OR]: 3.77; p < .001) and clear cell (OR: 6.38; p < .001) were most likely to undergo RLNS. Forty-five patients (7%) had positive nodes. Clear cell sarcoma (14%) and angiosarcoma (13%) had the highest rates of nodal positivity. Patients with positive nodes had reduced 5-year overall survival, and the stratification was largest in clear cell and angiosarcoma.

CONCLUSION

Discordance exists between selection for pathologic nodal evaluation and factors associated with nodal positivity. Clinically node negative patients with clear cell and angiosarcoma should be considered for pathologic nodal evaluation.

Molecular Characteristics of Genes and the Immune Microenvironment of a Rare Chest Malignant Tumor (Pulmonary Clear Cell Sarcoma): A Case Report

Pulmonary clear cell sarcoma is a rare malignant tumor that has rarely been reported and is challenging to diagnose, especially when differentiating from malignant melanoma. Currently, EWSR1-ATF1 is the key marker for distinguishing clear cell sarcoma from melanoma, but IHC has diagnostic limitations. We report a patient diagnosed with pulmonary clear cell sarcoma, in which an NGS was used to help with the pathological diagnosis. The exposure to the immune microenvironment in pulmonary clear cell sarcoma suggests that TIGIT-related drugs may be a new and effective treatment for this rare disease. Immune microenvironment-related markers, including PD-L1, CD8, TIM3, LAG3, and CD163, were negatively expressed in pulmonary clear cell sarcoma.

Primary Clear Cell Sarcoma of the Ileum: A Case Report With Next-Generation Sequencing Analysis

As the concept of clear cell sarcoma-like tumor or malignant gastrointestinal neuroectodermal tumor (CCS-LT/MGNET) has been widely accepted, primary CCS of the gastrointestinal tract (CCS-GI) is becoming a rare entity. In this article, we describe a case of primary CCS-GI that occurred in the ileum of a 65-year-old male to further illustrate its rare occurrence. Similar to CCS of soft tissue (CCS-ST), the tumor was composed of spindled to epithelioid cells displaying fascicular, nested, or pseudopapillary arrangement. The tumor cells had large round to ovoid nuclei with vesicular chromatin and prominent nucleoli, containing eosinophilic to pale cytoplasm. In contrast to CCS-LT/MGNET, immunohistochemical study also showed variable positivity of HMB45, melan A, and MiTF besides the strong and diffuse staining of S100 protein and SOX10. Fluorescence in situ hybridization (FISH) using fusion probes identified EWSR1 and ATF1 genes rearrangement. Next-generation sequencing (NGS) analysis further revealed EWSR1 exons9/8-ATF1 exon4 and ATF1 exon3- EWSR1 exon11 fusion genes. CCS-GI and CCS-LT/MGNET possibly represent 2 related entities of the same spectrum, which differentiate along 2 different pathways.

Childhood Clear Cell Sarcoma of Kidney: Incidence and Survival

This study is to describe current incidence of childhood clear cell sarcoma of kidney (CCSK) and to investigate the present survival of this cancer. Surveillance, Epidemiology, and End Result (SEER) data was used to identify children with CCSK and Wilms tumor (WT) aged 0-19 years in the US. Age-adjusted incidences were estimated over the decades. Age- and sex-specific epidemiology was also presented. Propensity score matching was used to balance features of CCSK and WT cases. Log rank test was used to compare survivals and Cox regression was used to evaluate independent effects of factors. The present age-adjusted incidence of childhood CCSK was 0.205 per million, which remained stable for years and ranked third in all pediatric renal tumors. The incidence rate ratios for boy and age under 4 were 3 and 21, respectively. The current 5-year overall survival (OS) rate for CCSK was 87%, which is not evidently inferior to that for WT (90%); however the outcome of CCSK was significantly poorer if both groups were well-balanced (OS rate was 86 vs. 95%). Early year of diagnosis and distant metastasis were independent survival factors. In conclusion, occurrence of CCSK remains stable over the years, with an age-adjusted incidence of 0.205 per million. Boy and age under 4 are risk factors for tumor development. CCSK currently has a favorable outcome but its nature may be more aggressive than common kidney tumor, which in turn proves efficacy of modern treatment.

Superficial Clear Cell Sarcoma (Melanoma of Soft Parts) of the Large toe in an 80-Year-Old Female With a Rare Cytogenetic Translocation

We present a case of clear cell sarcoma (CCS) on the left large toe of an 80-year-old female. CCS, also known as “melanoma of soft parts,” is a rare soft tissue neoplasm that exhibits melanocytic differentiation. Most cases occur on the distal extremities of young female adults. CCS shares histopathologic and immunohistochemical features with malignant melanoma that cause diagnostic difficulties distinguishing between these entities; therefore, cytogenetic studies of specific translocations are paramount in obtaining the correct diagnosis. The majority of CCS cases reveal a t(12;22)(q13;q12) EWSR1/ATF1 translocation, while a rare subset of CCS demonstrate a t(2;22) (q32:q12) EWS/CREB1 translocation. Our patient presented with a 50-year history of a nodule on the dorsum of her left large toe, with increasing size and tenderness over the past nine months. Histopathology and immunoperoxidase staining indicated CCS as a differential diagnosis. Cytogenetic analysis revealed a translocation in t(2;22) (q32;q12) resulting in the EWSR1/CREB1 gene, confirming a diagnosis of CCS. The translocation, histologic location, and long-standing clinical course exhibited in this case are exceptionally rare, and we hope to inform dermatologists of an uncommon presentation of CCS in an unexpected age group.

An obstructive role of NK cells on metastatic growth of clear-cell sarcoma cells in a xenoplant murine model

Clear cell sarcoma (CCS) affects the deep soft tissues in young adults and is known to have high rates of metastasis, including lymphatic metastasis. In our previous study an xenoplant model of CCS was established, which exhibited local tumor growth, lymphatic metastasis, and distant metastasis in SCID-Beige mice. In the current study, the role of NK cells during metastasis in the same xenoplant murine model was investigated. Injection of murine or human NK cells significantly suppressed the metastasis of HS-MM CCS cells in SCID-Beige mice. Notably, reverse transcription-quantitative PCR analysis demonstrated that injection of NK cells did not alter the mRNA expression levels of ERSR1-ATF1, which is specifically transcribed in CCS, in the buffy coat of circulating blood cells of HS-MM-xenoplanted SCID-Beige mice. BALB/c nude mice xenoplanted with HS-MM cells exhibited local growth without evident metastasis, whereas inoculation with the anti-asialo-GM1 antibody, which has previously been found to abolish NK-cell activity, resulted in metastasis of HS-MM cells in BALB/c nude mice. The injection of the anti-CD96 antibody, which increases the cytotoxicity of NK cells, significantly suppressed the metastasis of HS-MM cells in SCID-Beige mice. These results indicated that NK cells impaired the metastatic tumor microenvironments in the present mice xenoplant model.

Phase II trial of pazopanib in patients with metastatic or unresectable chemoresistant sarcomas: A Japanese Musculoskeletal Oncology Group study

Alveolar soft part sarcoma (ASPS), epithelioid sarcoma (ES), and clear cell sarcoma (CCS) are known to be chemoresistant tumors. The aim of this study was to investigate the effect of pazopanib on these chemoresistant tumors. This study is designed as a single‐arm, multicenter, investigator‐initiated phase II trial. Patient enrollment was undertaken between July 2016 and August 2018 at 10 hospitals participating in the Japanese Musculoskeletal Oncology Group. The primary end‐point is the CBR (CBR, including complete or partial response and stable disease) at 12 weeks after treatment with pazopanib according to RECIST. Eight patients were enrolled within the period. The histological subtypes were 5 ASPS, 2 ES, and 1 CCS. The median follow‐up period was 22.2 (range, 4.9‐24.9) months. All patients initially received pazopanib 800 mg once daily. The CBRs were 87.5% (7 of 8) and 75.0% (6 of 8) according to RECIST and Choi criteria at 12 weeks after pazopanib treatment, respectively. The CBRs at 12 weeks according to RECIST were 80.0%, 100.0%, and 100.0% in ASPS, ES, and CCS, respectively. Partial response was observed in 1 ASPS according to RECIST and 3 ASPS and 1 ES according to Choi criteria at 12 weeks after pazopanib treatment. This study documented antitumor activity of pazopanib, especially in ASPS. These results support the frontline use of pazopanib for ASPS. Prospective data collection is desired using both RECIST and Choi criteria for these rare chemoresistant tumors.

A rare case of primary dermal clear cell sarcoma with focal epidermotropism: An entity difficult to distinguish from melanoma

Clear cell sarcoma (CCS) is an uncommon soft-tissue sarcoma that only rarely arises within the dermis. It is challenging to distinguish dermal CCS from nodular, primary dermal, or metastatic melanoma, as they share morphologic features and immunoprofiles. We describe a dermal CCS in a 25-year-old man with a cutaneous groin mass. The lesion was initially diagnosed as melanoma, likely metastatic. On consultation, in addition to a melanoma-like tumor in the dermis, we identified focal infiltration of tumor cells into the overlying epidermis (epidermotropism), resembling primary nodular or metastatic melanoma. Given the patient's age and absence of a history of primary melanoma, fluorescence in situ hybridization (FISH) was performed, which revealed separation of the 5' and 3' EWSR1 probe signals on chromosome 22q12, prompting a diagnosis of CCS. Our case highlights the histopathological, immunohistochemical, and ultrastructural similarities between CCS and melanoma, and the consequent potential for major diagnostic confusion. In such cases, FISH analysis remains the key to diagnosis. CCS should be considered in patients with a melanoma-like tumor in the dermis or subcutaneous tissue without epidermal (or with minimal) involvement, or prior to diagnosing metastatic melanoma in the absence of a known history of primary melanoma, especially in young individuals.

Clear cell sarcoma of the esophagus: A rare location

Clear cell sarcoma of the esophagus is very rare. The etiology of this neoplasm remains unknown. Confirmed diagnosis requires histopathology with immunochemistry and molecular study. CCS typically shows highly aggressive behavior with a high rate of local recurrence, metastases, and death from disease.

A case report of cutaneous melanocytoma with CRTC1-TRIM11 fusion: Is CMCT distinct from clear cell sarcoma of soft tissue?

Pathological diagnosis of dermal melanocytic tumors is often problematic owing to histological resemblance. Recently, cutaneous melanocytoma with CRTC1-TRIM11 (CMCT) was added to this category. However, only six cases have been reported so far. We herein present a case of a 77-year-old Japanese man with CMCT. The patient presented a nodule in the right thigh and underwent surgical resection. Histological examination indicated a well-demarcated 6 × 5 mm-sized tumor nodule in the dermis and subcutis. The tumor was amelanotic, consisting of uniform nests and fascicles of spindled, or epithelioid cells. The melanocytic nature was evident by immunohistochemistry. The CRTC1-TRIM11 fusion was detected by TRIM11 immunostaining, chromogenic in situ hybridization, and RT-PCR/direct sequencing. He has been free from the tumor for 1 year after additional resection. The main differential diagnosis of CMCT includes primary and metastatic dermal malignant melanomas (MM) and dermal/subcutaneous clear cell sarcoma (CCS). Additionally, histological overlap with paraganglioma-like dermal melanocytic tumor was considered. Although some investigators argue that CMCT is a variant of CCS, we think it should be separated from CCS, and subcutaneous/dermal CCS should be confined to tumors with EWSR1-ATF1/ CREB1 fusion. However, longer follow-up and more case studies are needed for revealing the true prognosis of CMCT.

CD151 confers metastatic potential to clear cell sarcoma of the soft tissue in animal model

Cluster of differentiation 151 (CD151) is a potent therapeutic target for regulating tumor metastasis. In the present study, the role of CD151 in clear cell sarcoma of soft tissue was examined using a xenoplanted tumor model, which had high rates of metastasis. A clear cell sarcoma cell line, HS-MM, which was transplanted to the aponeuroses of the thighs, the most affected sites of human clear cell sarcoma, exhibited robust lymphatic invasion and nodal metastasis in SCID-beige mice. Serial in vivo passaging of peritoneally disseminated tumor cells accelerated the metastatic activity, which was accompanied by increased CD151 expression, and were designated as HS-MM^high. Notably, inoculation of anti-CD151 antibody significantly suppressed the lymphatic invasion, peritoneal dissemination and distant metastasis of the present clear cell sarcoma model without affecting local tumor growth at the transplantation site. Small interfering RNA (siRNA)-mediated downregulation of CD151 did not alter cell proliferation, but significantly inhibited Matrigel invasion activity of HS-MM^high cells. Downregulation of CD151 impaired matrix metalloproteinase-9 activity and phosphorylation of SMAD3 protein in HS-MM^high cells. The present results suggest that CD151 may contribute to invasion and metastasis of clear cell sarcoma of soft tissue. Therefore, CD151 may serve as a potent target to regulate metastasis of clear cell sarcoma.

Oral malignant gastrointestinal neuroectodermal tumour with junctional component mimicking mucosal melanoma

Malignant gastrointestinal neuroectodermal tumour (GNET) is a recently characterised rare and aggressive tumour that typically arises in association with the small intestine of adults. We present a novel case of this entity and expand the spectrum of its reported morphological features. The patient was a 5-year-old female, the youngest reported patient affected by the condition, and presented with extra-abdominal disease. The histopathological features included the presence of a junctional component of the palatal tumour, which mimicked mucosal melanoma, a feature that has not been previously reported in GNET. Whole genome and RNA sequencing was performed that demonstrated the EWSR1-ATF1 translocation characteristic of GNET. Knowledge of this entity and its features, together with careful morphological assessment supplemented by judicious immunohistochemical and molecular studies should enable the correct diagnosis to be established.

Imprint cytology of clear cell sarcoma-like tumor of the gastrointestinal tract in the small intestine: A case report

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is an extremely rare malignant neoplasm in the digestive tract. Its cytomorphologic features have never previously been reported. Here, we describe a case of CCSLGT, including its cytologic examination findings. A 47-year-old woman presented with a mass in the small intestine, which was resected and sent for imprint cytology. Imprint smears revealed tumor cells with light eosinophilic or clear cytoplasm in a necrotic background. Many of the tumor cells were arranged in a perivascular growth with a pseudopapillary formation, and there were some non-neoplastic osteoclast-like giant cells. Histological examination revealed solid nests and a pseudopapillary pattern of the tumor cells with clear or pale eosinophilic cytoplasm and large nuclei with small nucleoli. Immunohistochemistry showed positive for vimentin, S-100, and SOX-10, and negative for SMA, c-KIT, cytokeratin, HMB-45, and MelanA. The EWSR1 gene split signal was detected by reverse transcriptase fluorescence in situ hybridization, and EWSR1-CREB1 gene fusion was indicated by reverse transcriptase polymerase chain reaction analysis. From these findings, we diagnosed the tumor as CCSLGT. To best of our knowledge, this is the first description of the imprint cytology features of CCSLGT.

Primary clear cell sarcoma of the head and neck: a case series with review of the literature

BACKGROUND

Clear cell sarcoma typically arises in deep soft tissues of the foot/ankle. Primary head and neck clear cell sarcoma is rare. We report three molecularly confirmed primary head and neck clear cell sarcoma and review the literature.

METHODS

Head and neck clear cell sarcoma with no primary elsewhere were retrieved from archival/consultation files. English language literature review of all reported head and neck clear cell sarcoma was performed.

RESULTS

Three cases were identified. The tumors, all in men, presented on the scalp of a 33-year-old, face of a 20-year-old and tongue of a 44-year-old. Tumors ranged from 0.6 to 1.4 cm. All had typical features of clear cell sarcoma, including nests of tumor cells divided by fibrous septae. One had multinucleated wreath-like giant cells. One had a focal junctional component. Immunohistochemistry was positive for S100 (three out of three), HMB45 (three out of three) and Melan-A (two out of three). All had EWSR1 rearrangements by fluorescence in situ hybridization. Follow up available for one patient revealed no evidence of disease after wide excision and radiation. Seven additional reported cases were identified and tabulated.

CONCLUSION

Head and neck clear cell sarcoma is rare but should be considered in the differential diagnosis of nested tumors with fibrous septae. Molecular analysis should be considered for definitive diagnosis regardless of location.

Atypical amplification of chromosome region 22q12 in melanoma: A case report

Morphological, ultrastructural and immunohistochemical characteristics of clear cell sarcoma (CCS) of the soft tissue frequently overlap with those of malignant melanoma. Thus, the differential diagnosis between the two lesions represents an important diagnostic dilemma. However, a number of genetic factors can be used to differentiate the two tumors; in particular, the t(12;22)(q13;q12) chromosomal translocation is typical of CCS, resulting in fusion of the EWSR1 gene on chromosome 22q12 and the ATF1 gene on chromosome 12q13. The detection of this molecular alteration has proved useful in the differential diagnosis of the two lesions. The present study reports the case of a 71-year-old male patient with a suspicious lymph node mass. Immunohistochemical analysis of the lesion indicated a diagnosis of metastatic melanoma, however, cytogenetic analysis using fluorescence in situ hybridization was additionally performed to investigate the chromosomal rearrangements of the 22q12 region and completely exclude the possibility of CCS. The current case did not demonstrate the presence of the translocation, supporting the diagnosis of melanoma. However, a clear orange amplification signal was observed relative to an ~500-kb region adjacent to the EWSR1 gene in the centromeric direction of chromosome 22q12. To the best of our knowledge, this is the first description of a 22q12 chromosomal alteration in melanoma. Furthermore, despite the presence of numerous genes in this region, their amplification has not previously been associated with the pathogenesis of melanoma.

Primary malignant neuroectodermal tumor of the ileum with predominantly uncommon pseudopapillary architecture

A malignant gastrointestinal neuroectodermal tumor (GNET), a distinctive entity covering the characteristics of clear cell sarcoma (CCS) of gastrointestinal tract described recently, arising primarily in the ileum of a 33-year-old woman is reported. Histologically, the neoplasm involved the full thickness of the intestinal wall. Tumor cells, mainly displayed epithelioid or polygonal appearance with oval or round nuclei, arranged in strand, nested, and solid pattern with prominent pseudopapillary architecture instead of the familiar histological image with multinucleated osteoclast-like giant cells. They were positive for vimentin, S-100, synaptophysin, CD56 and CD99 protein, but negative for AE1/AE3, EMA, CEA, LCA, Desmin, CK7, CK20, Villin, CgA, CD117, Dog-1, GFAP, Melan-A, HMB-45, CD34, CR, WT1, D2-40. Fluorescence in situ hybridization (FISH) showed the presence of chromosomal translocation involving EWSR. The patients lived through a calm period after a tumor resection and 4 cycles of chemotherapy combining ifosfamide and epirubicin. This case demonstrates that GNET is a rare tumor in gastrointestinal tract, and furthermore, various misleading histological characteristics should been taken into consideration in the diagnosis.

Clear cell sarcoma of the kidney: patients' characteristics and improved outcome in developing countries

BACKGROUND

Clear cell sarcoma of the kidney (CCSK) is a rare and aggressive tumor accounting for 5% of pediatric renal tumors with an incidence of 20 patients per year in the USA. It is bone metastasizing with poor prognosis. Our aim was to show characteristics of patients in relation to improved outcome in one of the developing countries.

PROCEDURE

We included all patients diagnosed as CCSK in the period between July 2007 and March 2012 at Children's Cancer Hospital, Egypt. Patients' demographics, clinical presentation, pathology, and management were reviewed. Follow up was continued until April 2013.

RESULTS

Twenty-five patients were identified in the defined time interval, accounting for 7% all renal tumors diagnosed at the hospital. Mean age was 36 months. Abdominal swelling and hematuria were the most common presentations. Stages I, II, III, IV, and V represented 9 (36%), 3 (12%), 8 (32%), 3 (12%), and 2 (8%), respectively. Twenty-four patients had radical nephrectomy either upfront or after neo-adjuvant chemotherapy. Surgery was followed by adjuvant chemotherapy. Abdominal radiotherapy was given for local stages II and III. Twenty-two patients reached complete remission, while one patient had stationary disease and two patients died due to progression and relapse. Overall survival was 88.5% and event-free survival was 87.8% at 45 months.

CONCLUSION

Although previous studies indicate poor prognosis of CCSK, our experience shows that those patients can be treated using extensive chemotherapy combined with proper local control.

Pediatric gastrointestinal PEComas: a diagnostic challenge

Perivascular epithelioid cell tumors (PEComas) in the pediatric population are very rare and frequently arise in the gastrointestinal tract. These tumors are characterized by variable morphological and immunohistochemical features, which may pose significant problems in differential diagnosis with other gastrointestinal mesenchymal tumors in pediatric patients. In presenting an unusual pediatric case of gastrointestinal PEComa, we also discuss the possible differential diagnosis of this rare entity.

Children's Oncology Group's 2013 blueprint for research: renal tumors

Renal malignancies are among the most prevalent pediatric cancers. The most common is favorable histology Wilms tumor (FHWT), which has 5-year overall survival exceeding 90%. Other pediatric renal malignancies, including anaplastic Wilms tumor, clear cell sarcoma, malignant rhabdoid tumor, and renal cell carcinoma, have less favorable outcomes. Recent clinical trials have identified gain of chromosome 1q as a prognostic marker for FHWT. Upcoming studies will evaluate therapy adjustments based on this and other novel biomarkers. For high-risk renal tumors, new treatment regimens will incorporate biological therapies. A research blueprint, viewed from the perspective of the Children's Oncology Group, is presented.

Rare non-Wilms' tumors in children

We report our institutional experience of the management of 2 cases of rare non-Wilms' tumors; a rhabdoid tumor in a 17-month old boy and a clear cell sarcoma in a 5-year old girl. The two patients were treated with ifosfamide/carboplatin/etoposide (ICE) alternating with vincristine/doxorubicin/cyclophosphamide (VDC) and cyclophosphamide/etoposide (CE) alternating with vincristine/doxorubicin/cyclophosphamide (VDC) and radiotherapy, respectively. Both patients showed full response with no significant adverse events. At 2-year follow up, they are disease and relapse free. Although contemporary treatment regimens are very promising, multicenter collaborative studies are needed in order to define a standard treatment for non-Wilms' tumors.

Abscess mimicking lung metastasis in a 10-year-old boy - case report

BACKGROUND

Malignant pulmonary tumours in children are very rare; the majority are metastases. Nonspecific radiographic findings of these abnormalities are challenging and may delay the final diagnosis and treatment.

CASE REPORT

A 10-year-old boy was admitted to our hospital because of the clinical and radiographic symptoms and signs of pneumonia with abscess formation in the left lower lobe. After initial improvement on antibiotic therapy, a significant deterioration of the patient's condition was observed, together with progression in radiographic examinations. The patient was treated surgically and transferred to the Haematology and Oncology Department with a final diagnosis of pulmonary metastasis of clear cell sarcoma.

CONCLUSIONS

Radiographic findings of metastatic diseases may mimic non-neoplastic pulmonary conditions. A lack of specific clinical symptoms and a confusing radiographic pattern in our patient with clear cell sarcoma lung metastasis caused serious diagnostic difficulties.

The melanocyte inducing factor MITF is stably expressed in cell lines from human clear cell sarcoma

Clear cell sarcoma (CCS) is associated with the EWS/ATF1 oncogene that is created by chromosomal fusion of the Ewings Sarcoma oncogene (EWS) and the cellular transcription factor ATF1. The melanocytic character of CCS suggests that the microphthalmia-associated transcription factor (Mitf), a major inducer of melanocytic differentiation, may be miss-expressed in CCS. Accordingly, we show that the mRNA and protein of the melanocyte-specific isoform of Mitf (Mitf-M) are present in several cultured CCS cell lines (Su-ccs-1, DTC1, Kao, MST-1, MST-2 and MST-3). The above cell lines thus provide a valuable experimental resource for examining the role of Mitf-M in both CCS and melanocyte differentiation. Melanocyte-specific expression of Mitf-M is achieved via an ATF-dependent melanocyte-specific cAMP-response element in the Mitf-M promoter, and expression of Mitf-M in CCS cells suggests that EWS/ATF1 (a potent and promiscuous activator of cAMP-inducible promoters) may activate the Mitf-M promoter. Surprisingly, however, the Mitf-M promoter is not activated by EWS/ATF1 in transient assays employing CCS cells, melanocytes or nonmelanocytic cells. Thus, our results indicate that Mitf-M promoter activation may require an appropriate chromosomal context in CCS cells or alternatively that the Mitf-M promoter is not directly activated by EWS/ATF1.

Malignant melanoma is genetically distinct from clear cell sarcoma of tendons and aponeurosis (malignant melanoma of soft parts)

Clear cell sarcoma of tendons and aponeuroses (malignant melanoma of soft parts) and conventional malignant melanoma may demonstrate significant morphologic overlap at the light microscopic and ultrastructural level. Consequently, the clinically relevant distinction between primary clear cell sarcoma and metastatic melanoma in the absence of a known primary cutaneous, mucosal or ocular tumour may occasionally cause diagnostic problems. A balanced translocation, t(12;22)(q13;q13), which can be detected, amongst others, using the reverse transcriptase polymerase chain reaction (RT-PCR) or fluorescent in situ hybridization (FISH), has been identified in a high percentage (50-75%) of clear cell sarcomas and is presumed to be tumour specific. Whether this chromosomal rearrangement is present in malignant melanoma has, to date, not as yet been studied by molecular genetic or molecular cytogenetic techniques. Using RT-PCR and FISH, a series of metastases from 25 known cutaneous melanomas and 8 melanoma cell lines (5 uveal and 3 cutaneous) were screened for the t(12;22)(q13;q13) translocation. Primers for RT-PCR were chosen based upon published breakpoint sequences. The Cosmids G9 and CCS2.2, corresponding to the 5' region of EWS and 3' region of ATF-1 respectively, were used as probes. The translocation was not identified in any of the melanomas or melanoma cell lines analysed in this study; in contrast this translocation was identified in 3 out of 5 clear cell sarcomas using these techniques. This allows distinction between translocation positive cases of clear cell sarcoma and malignant melanoma at a molecular genetic level. Consequently, in diagnostically challenging cases, this represents a valuable tool for the clinicopathologic differentiation between these two entities, with an important impact on patient management and prognosis.