Abdominopelvic desmoplastic small round cell tumor with metastasis: A case report and literature review.

RATIONALE: Desmoplastic small round cell tumor (DSRCT) is a rare and rapidly metastasizing soft tissue sarcoma, distinguished by its unique cell morphology and pleomorphic differentiation. PATIENT CONCERNS: This report describes the case of an 18-year-old male diagnosed with abdominopelvic DSRCT exhibiting metastases to the peritoneum, liver, pleura, bone, and muscle. The patient primarily presented with symptoms of incomplete intestinal obstruction and an abdominal mass. DIAGNOSES: Colonoscopy revealed lumen stenosis caused by external compression mass. Contrast-enhanced computed tomography and 18F-fluorodeoxyglucose positron emission tomography/computed tomography revealed multiple lesions in the abdominopelvic cavity. A needle biopsy of an abdominal wall lesion established it as a malignant tumor, origin unknown. Immunohistochemical staining post-surgery showed positive results for Cytokeratin (CK), CK7, Desmin, Vimentin, Caudal type homeobox 2 (CDX2), and Ki-67. Fluorescence in situ hybridization analysis revealed an Ewing sarcoma breakpoint region 1/EWS RNA binding protein 1 (EWSR1) rearrangement, and next-generation sequencing identified an EWSR1-Wilms tumor protein 1 (WT1) gene fusion. INTERVENTIONS: The patient underwent laparoscopic exploratory surgery, which encompassed biopsy, ascites drainage, adhesion lysis, reinforcement of weakened sections of the small intestinal walls, and repositioning of twisted intestines. Postoperatively, the treatment protocol included fasting, rehydration, gastrointestinal decompression, and parenteral nutrition. However, the patient did not received chemotherapy. OUTCOMES: The patient declined further treatment and deceased in early November. LESSONS: This case highlights the nonspecific nature of DSRCT symptoms. In clinical practice, it is crucial to meticulously evaluate unexplained intestinal obstruction in young patients, considering DSRCT as a differential diagnosis to avoid delays in diagnosis.

Desmoplastic small round cell tumor of the abdomen: A case report.

RATIONALE: Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor with poor prognosis, usually involving the peritoneum. There are currently no standardized treatment approaches. This study helped to further advance our understanding of DSRCT, and help to guide therapy. PATIENT CONCERNS: The patient, a 19-year-old male, presented with left-sided back pain with no obvious cause and occasional abdominal pain, and underwent abdominal electron computed tomography examination in our hospital suggesting consideration of small bowel mesenchymal tumor with possible multiple implantation metastasis in the abdominopelvic cavity. DIAGNOSES: After surgical treatment, the pathology report suggested a DSRCT, and immunohistochemistry and fluorescence in situ hybridization revealed EWSR1-WT1 gene rearrangement. Lung computer tomography and abdominal magnetic resonance imaging performed half a month later showed multiple solid nodules on the proximal septal surface of the right lung base, right posterior cardiac/right anterior inferior vena cava nodules, and multiple nodules in the abdominopelvic cavity, omenta, peritoneum, and around the liver or liver, all of which were considered as metastatic foci. INTERVENTIONS AND OUTCOMES: Patient received 5 cycles of chemotherapy after surgery. The review results showed a smaller size than before. Currently, he continues to receive treatment. LESSONS: The reported case has raised awareness of the importance of DSRCT in the treatment of chemotherapy, including its role in the differential diagnosis of abdominal tumors.

Desmoplastic small round cell tumor of the liver: diagnosing a rare case on liver biopsy.

Desmoplastic small round-cell tumors (DSRCT) frequently develop in the retroperitoneum, pelvis, omentum, and mesentery. Here, we present an unusual case of primary DSRCT in the liver. The patient was an 11-year-old boy with multiple solid masses in the liver parenchyma. The tumor in the needle biopsy had a histology revealing a small round cell morphology and desmoplasia. It shows the immunohistochemical features of DSRCT and documentation of EWSR1-WT1 fusion.A potential diagnostic pitfall is exerted when evaluating liver biopsy, in which DSRCT is a great mimicker and may be easily confused with more common liver malignancies of childhood, such as hepatoblastoma, calcifying nested stromal-epithelial tumor, undifferentiated embryonal sarcoma, and other small round cell tumors, as well as the fibrolamellar variant of hepatocellular carcinoma. This distinction is critical because an accurate therapeutic approach requires a correct diagnosis.

Desmoplastic Small Round Cell Tumor Involving Serous Fluid: Cytologic Features and Diagnostic Pitfalls: A Series of 8 Cases.

OBJECTIVES: When desmoplastic small round cell tumor (DSRCT) is present in serous fluid, the cytomorphology can be diverse and can mimic metastatic carcinomas and thus present a diagnostic challenge. The aim of this study was to evaluate the cytomorphologic and immunocytochemical features of this rare tumor in serous effusion specimens. METHODS: Demographic, clinical, radiologic, and pathologic information from patients who had a DSRCT diagnosis on body fluid specimens was collected and cytologic slides were reviewed. RESULTS: Nine specimens were identified (5 pleural fluid and 4 ascitic fluid specimens) from 8 patients (5 male and 3 female). The mean patient age at diagnosis was 26 years. The most common symptoms were abdominal distension and pain, with 5 patients having abdominal masses. Other findings included peritoneal carcinomatosis, liver masses, ascites, and pleural nodules. The predominant cytomorphology was loose cellular clusters, followed by tight clusters of small cells with scant occasional vacuolated cytoplasm and a sphere-like pattern. CONCLUSIONS: Serous fluid may be the first available specimen to diagnose DSRCT. In young patients with no history of malignancy and radiologic finding of peritoneal implants, DSRCT should be considered a possibility in the differential diagnosis, and sensitive markers should be used for accurate diagnosis.

Desmoplastic Small Round Cell Tumor of the Head and Neck: A Clinicopathological, Immunohistochemical and Molecular Analysis of Three Cases with Literature Review.

Desmoplastic small round cell tumor (DSRCT) is a rare aggressive malignancy typically originating from the abdominal or pelvic cavity. DSRCT presenting as a primary head and neck tumor has rarely been described in the literature. We present three cases of DSRCT arising in the head and neck to further characterize its clinicopathological features. All three patients were male and aged 36, 30 and 17 years. The involved sites included the orbit (1 case) and submandibular gland (2 cases). The tumors ranged in size from 2.4 to 3.5 cm (mean, 2.1 cm). Histologically, all tumors showed irregular-shaped, variable-sized nests of small round cells deposited in an abundant desmoplastic stroma. Tumor cells contained scant amounts of eosinophilic cytoplasm and small hyperchromatic nuclei with inconspicuous nucleoli. Immunohistochemically, the tumors were positive for keratin (AE1/AE3) (3/3), desmin (3/3), vimentin (2/2), NSE (1/1) and EMA (1/1). Fluorescence in situ hybridization (FISH) analysis demonstrated the presence of EWSR1 and WT1 rearrangements in all three cases. All patients received surgery and adjuvant chemotherapy and/or radiotherapy. There was no evidence of recurrence and metastasis in two patients, and the third suffered lung metastasis. DSRCT arising in the head and neck represents an extremely rare condition. It is easily mistaken as poorly differentiated carcinoma due to similar morphology and expression of epithelial markers. Immunohistochemistry assay in conjunction with molecular detection of EWSR1::WT1 fusion will be helpful for arriving at an accurate diagnosis to avoid misdiagnosis and inappropriate treatment.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series.

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

Selective Immunoreactivity for WT1 Carboxy-Terminus Distinguishes Desmoplastic Small Round Cell Tumor From its Histologic Mimics.

Desmoplastic small round cell tumor (DSRCT) is an aggressive pediatric round cell sarcoma containing a characteristic EWSR1-WT1 gene fusion. In the absence of genetic data, distinguishing DSRCT from other small round cell tumors of childhood can be problematic due to overlapping histologic and immunohistochemical features. We studied the utility of immunohistochemistry with antibodies targeting both the amino-terminal and carboxy-terminal regions of the Wilms tumor-1 (WT1) protein in differentiating these groups of tumors. The study cohort included 33 cases of genetically confirmed pediatric round cell tumors (10 DSRCTs, 12 Wilms tumors, 10 Ewing sarcomas, and 1 CIC-rearranged sarcoma). Immunoreactivities and immunolocalization of both the WT1 amino-terminus and carboxy-terminus were scored and documented. All DSRCTs displayed selective reactivity for only the WT1 carboxy-terminus (10/10), while dual immunoreactivity for both the WT1 carboxy-terminus (12/12) and amino-terminus antibodies (12/12) were characteristic of Wilms tumors. CIC-rearranged sarcoma showed variable WT1 nuclear immunopositivity (1/1, 1/1) and Ewing sarcomas were consistently WT1-negative for both the WT1 amino-terminus (0/10) and carboxy-terminus (0/10). Dual WT1 amino-terminus and carboxy-terminus immunohistochemistry remains a helpful diagnostic tool in discriminating intraabdominal small round cell tumors, which serves as an adjunct to the genetic information in preventing misdiagnosis.

Primary desmoplastic small round cell tumor of the submandibular gland: a case report and literature review.

BACKGROUND: Desmoplastic small round cell tumor (DSRCT) is a sporadic, highly malignant tumor with a poor prognosis. The abdomen and pelvis have been reported as the primary localization sites. However, to the best of our knowledge, there are few reports on primary DSRCT in the submandibular gland. CASE PRESENTATION: We report a case of a 26-year-old Chinese man with a mass in the right submandibular gland. Imaging studies showed a hypoechoic mass in the right submandibular region. Intraoperative pathology revealed that the tumor tissue was composed of small round tumor cells and a dense desmoplastic stroma. On immunostaining, the tumor cells showed markers of epithelial, mesenchymal, myogenic, and neural differentiation. The EWSR1 gene rearrangement was detected by fluorescence in situ hybridization. Based on the overall morphological features and immunohistochemical findings, a final diagnosis of DSRCT was made. The patient was treated with comprehensive anti-tumor therapy mainly based on radiotherapy and chemotherapy. CONCLUSIONS: DSRCT is an uncommon malignant neoplasm with rare submandibular gland involvement. In this report, we have described a case of DSRCT in the submandibular gland and reviewed the literature on DSRCT over the past 5 years. Considering the importance of differential diagnosis between DSRCT, especially with rare extra-peritoneal involvement, and small round blue cell tumors, a full recognition of the clinicopathological features will help to better diagnose this neoplasm.

Primary Desmoplastic Small Round Cell Tumor of the Femur: Case Report and Review of a Rare Intraosseous Malignancy.

Background: Desmoplastic small round cell tumors (DSRCT) are malignant neoplasms of young males arising most commonly in the abdominopelvic cavity, with a subset originating from extra-abdominal soft tissues. As either primary or metastatic lesions, they are rare in intraosseous sites. Case Presentation: We describe the fifth report of primary DSRCT of bone. A healthy 18-year old male presented with a blastic, 17 cm lesion within the left distal femur, suspicious for osteosarcoma or Ewing sarcoma. Subsequent biopsy revealed nests of small round blue cells infiltrating through a desmoplastic stroma. These cells were diffusely positive for epithelial markers, with paranuclear staining for desmin and focal reactivity with NSE. Break-apart FISH revealed a rearrangement in EWSR1, and RNA fusion panel confirmed WT1 as its partner in the pathognomonic t(11;22)(p13;q12) rearrangement. PET/CT showed widespread metastatic disease to visceral and bony sites. Conclusions: Due to their rarity as well as clinicopathologic and immunomorphologic overlap, primary intraosseous DSRCT can create diagnostic challenges with the more frequently encountered tumors of bone.

Desmoplastic Small Round Cell Tumor of the Submandibular Gland: A Case Report and Literature Review.

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressively malignant tumor mostly occurring in the abdominal and pelvic cavity of young patients. However, few cases had been reported concerning DSRCT occurring in the head and neck region. We presented a rare case of DSRCT of the right submandibular in a 25-year-old man. MRI revealed a 3 × 2-cm solid nodule located in the right submandibular, and physical examination showed no other occupying lesion elsewhere. Histologically, the tumor was composed of various-sized small round cell nests, embedded in an abundant desmoplastic stroma. Immunohistochemically, the tumor cells were typically positive for epithelial (CK and EMA), mesenchymal (vimentin and desmin), and neuroendocrine (CD56, NSE, Syn, and CgA) markers, but negative for WT1. Fluorescence in situ hybridization revealed the presence of a break apart involving the Ewing sarcoma (EWS) gene. The patient received chemotherapy and radiotherapy and relapsed after 19 months of follow-up. DSRCT of the submandibular gland is rare, and the diagnosis of this tumor in an uncommon location relies on the histomorphology, immunophenotype, and EWS gene translocation detection. Differential diagnosis including primary salivary gland tumors and the other small round cell tumors needs to be excluded.

A rare cause of bilateral pleural effusion - desmoplastic small round cell tumor.

Desmoplastic small round cell tumor (DSRCT) is a rare, extremely aggressive and malignant tumor predominantly affects young adolescent males and typically presents as a large intra-abdominal mass. However, tumor arising from other body sites are also reported in the literature. Histology and immunohistochemistry play an important role in the diagnosis and differentiating this rare tumor from other round cell tumors. A multidisciplinary approach consisting of a combination of surgery, chemotherapy and radiation therapy is the treatment of choice as there is no standard therapy.  We report a case of DSRCT of pleura presenting as bilateral pleural effusion in a young adolescent male who was treated with both surgery and chemotherapy. However, the patient succumbed to illness after one year of diagnosis.

Common Pitfalls in Ewing Sarcoma and Desmoplastic Small Round Cell Tumor Diagnosis Seen in a Study of 115 Cases.

Ewing sarcoma (ES), "Ewing-like sarcoma" (ELS) and desmoplastic small round cell tumors (DSRCT) can masquerade as other tumor types, particularly neuroendocrine neoplasms and receive inappropriate treatment. We retrieved 115 cases of ES, ELS and DSRCT seen over 17 years in a tertiary center. An initial misdiagnosis or incomplete diagnosis occurred in 6/93 (6.4%) of ES/ELS and 5/22 (22.7%) of DSRCT cases. The most frequent misdiagnosis was small cell neuroendocrine carcinoma. While any misdiagnosis or incomplete classification is almost certainly multifactorial, the most common identified reason for erroneous/incomplete initial reporting was expression of neuroendocrine markers. Other contributing factors included keratin expression, older patient age and apparently unusual tumor location. Most patients treated with a non-sarcoma chemotherapy regimen expired, while those who received a sarcoma-related regimen were alive as of last evaluation. Increased awareness of this diagnostic pitfall is needed in evaluating cases of round cell malignancies.

Clinicopathological features of desmoplastic small round cell tumors: clinical series and literature review.

BACKGROUND AND PURPOSE: Desmoplastic small round cell tumor (DSRCT) is a highly malignant sarcoma that occurs in the abdominopelvic cavities of adolescents. The accurate diagnosis of DSRCT is challenging owing to limited literatures. Our study aimed to investigate the relationship between clinicopathological features and prognosis in patients with DSRCTs. METHODS: Data of 8 patients with DSRCT originating from the abdominal cavity were retrospectively reviewed. The clinical manifestations, pathological characteristics, treatment approaches, and prognosis were analyzed. The histopathological (identified using hematoxylin-eosin staining), immunohistochemical, and molecular diagnostic (using fluorescence in situ hybridization) features were also reviewed. RESULTS: All patients were male aged between 24 and 45 years (median age, 30 years). The main clinical symptoms included abdominal distension, abdominal pain, and constipation. Seven of the 8 patients developed metastases to either distant organs or lymph nodes. Multiple gray nodules with diameters of 1-10 cm and poorly defined boundaries were scattered throughout the omentum and mesentery. Histopathological examination demonstrated well-defined nests composed of small round blue cells separated by markedly desmoplastic stroma. Immunohistochemical analysis revealed positive expressions of desmin, vimentin and C-terminal of Wilm's tumor suppressor (WT-1). The Ewing sarcoma breakpoint region 1 gene fused with WT1 (EWSR1-WT1) gene fusion was detected in all patients. Cytoreductive surgery (CRS) was performed in 6 patients. Follow-up period ranged from 7.5 to 28.5 months with a median of 17.2 months. Three patients died during follow-up. CONCLUSION: DSRCT is highly aggressive and presents distinctive morphological features. CRS is the essential therapy for DSRCT. A test for the combined expression of desmin, cytokeratins, and C-terminal of WT-1, as well as the analysis of morphologic features, might be helpful during DSRCT diagnosis, and the EWSR1-WT1 gene fusion is the gold standard for definitive diagnosis. Our work will provide new insights into the diagnosis and treatment of DSRCTs.

NKX3.1 a useful marker for mesenchymal chondrosarcoma: An immunohistochemical study.

INTRODUCTION: Mesenchymal chondrosarcoma is a rare subtype of chondrosarcoma. The tumor has a characteristic bimorphic pattern with areas of poorly differentiated small round cell component and interspersed islands of well differentiated hyaline cartilage. Histological diagnosis of mesenchymal chondrosarcoma is very challenging especially in small biopsies when tumor presents with little cartilaginous component. In such cases, it is very difficult to distinguish mesenchymal chondrosarcoma from other round blue cell tumors like Ewing's sarcoma, rhabdomyosarcoma, small cell osteosarcoma and desmoplastic round blue cell tumor. Immunohistochemically, mesenchymal chondrosarcoma stains positive for NKX2.2, CD99, S100 and SOX9. This immunoprofile is non-specific and overlaps with other round blue cell tumors. Till recently, there was no reliable immunohistochemical marker to differentiate mesenchymal chondrosarcoma from other round blue cell tumors. NKX3.1, though widely used as a diagnostic biomarker for prostatic adenocarcinoma, has been recently proposed by Yoshida et al. (2020) as a unique marker of mesenchymal chondrosarcoma and EWSR1-NFATC2 sarcoma. OBJECTIVE: The aim of our study was to further explore utility of NKX3.1 as a diagnostic marker of mesenchymal chondrosarcoma. MATERIAL & METHODS: We applied NKX3.1 immunohistochemistry to 21 cases of mesenchymal chondrosarcoma and 32 cases of other round blue cell tumors. RESULTS: 14 out of 21 cases (66.7%) of mesenchymal chondrosarcoma stained positive for NKX3.1 with nuclear expression in small round component. Cartilaginous component was predominantly negative. All other round blue cell tumors showed negative results. CONCLUSION: Based on our study results we suggest that NKX3.1 is a useful immunohistochemical marker in differentiating mesenchymal chondrosarcoma from its histological mimics.

Small Round Blue Cell Sarcoma Other Than Ewing Sarcoma: What Should an Oncologist Know?

OPINION STATEMENT: The diagnosis of round cell sarcomas has changed rapidly over the last decade, causing much diagnostic confusion for pathologists and oncologists. The advances in diagnosis are largely due to the advent of next-generation sequencing techniques, which allowed the recognition of novel gene fusions in round cell sarcomas. The new 5th edition of the WHO Classification of Tumors of Soft Tissue and Bone recognizes four subgroups of undifferentiated round cell sarcomas: Ewing sarcoma, CIC-rearranged sarcomas, BCOR-altered sarcomas, and sarcomas with EWSR1-non-ETS fusions, in addition to desmoplastic small round cell tumor. This classification is based on a variety of publications showing that each of these molecular subtypes has unique clinical and prognostic characteristics distinct from Ewing sarcoma, therefore supporting the validity of recognizing these as discrete diagnostic entities. Despite our improved ability to diagnose these new round cell sarcomas, there remains confusion on how best to identify and treat these tumors. However, several key clinicopathologic features can point the physician toward the correct diagnosis. The goal of the following article is to emphasize the key clinical, pathologic, molecular, and prognostic differences between Ewing sarcoma and these non-Ewing round cell malignancies to improve recognition of these rare diseases.