Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical and molecular study of four patients

Small round cell sarcomas

Undifferentiated small round cell sarcomas (SRCSs) of bone and soft tissue comprise a heterogeneous group of highly aggressive tumours associated with a poor prognosis, especially in metastatic disease. SRCS entities mainly occur in the third decade of life and can exhibit striking disparities regarding preferentially affected sex and tumour localization. SRCSs comprise new entities defined by specific genetic abnormalities, namely EWSR1-non-ETS fusions, CIC-rearrangements or BCOR genetic alterations, as well as EWSR1-ETS fusions in the prototypic SRCS Ewing sarcoma. These gene fusions mainly encode aberrant oncogenic transcription factors that massively rewire the transcriptome and epigenome of the as yet unknown cell or cells of origin. Additional mutations or copy number variants are rare at diagnosis and, depending on the tumour entity, may involve TP53, CDKN2A and others. Histologically, these lesions consist of small round cells expressing variable levels of CD99 and specific marker proteins, including cyclin B3, ETV4, WT1, NKX3-1 and aggrecan, depending on the entity. Besides locoregional treatment that should follow standard protocols for sarcoma management, (neo)adjuvant treatment is as yet ill-defined but generally follows that of Ewing sarcoma and is associated with adverse effects that might compromise quality of life. Emerging studies on the molecular mechanisms of SRCSs and the development of genetically engineered animal models hold promise for improvements in early detection, disease monitoring, treatment-related toxicity, overall survival and quality of life.

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.

Desmoplastic Small Round Cell Tumor with "Pure" Spindle Cell Morphology and Novel EWS-WT1 Fusion Transcript: Expanding the Morphological and Molecular Spectrum of This Rare Entity

Background: Desmoplastic small round cell tumor (DSRCT) is a rare pediatric soft tissue neoplasm composed of small round tumor cells with prominent stromal desmoplasia, polyphenotypic differentiation and EWSR1-WT1 gene fusion. We, herein, present a unique case of DSRCT, exhibiting a pure spindle cell morphology, absence of desmoplastic stroma and showing a novel EWS-WT1 fusion transcript. Methods: A 12-year-old boy presented multiple intra-abdominal, confluent and mass-forming nodules that affected the entire abdominal and pelvic cavities. Results: Histologically, the nodules were composed of spindle cells with scant cytoplasm and oval nuclei arranged into short, intersecting fascicles and set in a scant, non-desmoplastic, stroma. Immunohistochemically, neoplastic cells were stained with vimentin, desmin, WT-1 (C-terminus antibodies) and EMA. Reverse-transcriptase polymerase chain reaction (RT-PCR) analysis showed the presence of an unusual chimeric transcript, composed of an in-frame junction of exon 9 of EWS to exon 7 of WT1, confirming the histological diagnosis of DSRCT. Conclusions: The present case contributes to widen the morphological spectrum of this entity; notably, the additional presence of a novel chimeric fusion transcript contributes to making the present case even more unique. Whether the detection of the above-mentioned fusion transcripts could explain the unusual morphology of the tumor remains to be established.

Desmoplastic small round cell tumor of the parotid gland-report of a rare case and a review of the literature

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is a rare soft tissue tumor that generally involves the retroperitoneum, pelvis, omentum and mesentery in younger patients. However, extra-abdominal DSRCT is very rare.

CASE PRESENTATION

A 49-year-old Japanese man noticed a mass in the right parotid gland. Ultrasound examination revealed a solid tumor about 2 cm in diameter. Computed tomography (CT) of the whole body revealed no other tumors or lymph node swelling. Superficial parotidectomy was performed. Histologically, the tumor was composed of various-sized tumor cell nests in an abundant fibromyxoid and collagenous background. The tumor cells were small to medium-sized. Immunohistochemistry showed that the tumor cells were immunoreactive for epithelial markers and desmin. They also showed strong nuclear staining with a Wilms tumor 1 (WT1) antibody detecting the C-terminal region (C-WT1), but not the N-terminal region (N-WT1). We also performed 3'/5' expression imbalance assay based on reverse transcription polymerase chain reaction (RT-PCR) to determine whether aberrant WT1 gene expression was present. This tumor was found to lack 5'-regional expression of the WT1 gene, as well as immunoreactivity with the N-WT1 antibody. Finally, fluorescence in situ hybridization (FISH) and RT-PCR analyses revealed the presence of a gene showing fusion between exon 7 of EWSR1 and exon 8 of WT1. The tumor was diagnosed as a DSRCT of the right parotid gland. The patient has been followed for 3 years without recurrence or metastasis.

CONCLUSIONS

Although DSRCT in the salivary gland is extremely rare, it should be included in the differential diagnosis of poorly differentiated salivary gland neoplasms, especially with a fibromyxoid background. Pathologists should bear in mind that DSRCT may occur in major salivary glands and should perform immunohistochemistry with appropriate antibodies, not only those against keratin and desmin, but also one detecting the C-terminal region of WT-1. Furthermore, molecular detection of EWSR1-WT1 fusion gene conclusively confirmed the diagnosis of DSRCT in this uncommon location.

A national analysis of patterns of care and outcomes for adults diagnosed with desmoplastic small round cell tumors in the United States

BACKGROUND

Because of the rarity of desmoplastic small round cell tumors (DSRCT), there is a lack of data describing patterns of care and survival for these patients. Using a national tumor registry, the current study sought to describe patterns of care and clinical outcomes for patients with DSCRT.

METHODS

Data from the National Cancer Database were used to identify 491 patients aged 18 years or older diagnosed with DSRCT between 2004 and 2014. Multivariable Cox proportional hazards regression analysis was used to identify factors associated with overall survival (OS).

RESULTS

Among all patients, 41.2% (n = 200), underwent surgical resection of their primary tumor, chemotherapy was administered to 86.5% (n = 415) of patients, while radiation therapy was administered to 13.0% (n = 63) of patients. Over the study, 69.7% of patients died with a median OS of 25.9 months (interquartile range [IQR]: 22.7-27.5); 1-, 3-, and 5-year OS were 78.6%, 32.3%, and 18.4%, respectively. On multivariable analysis, stage IV disease (Hazard Ratio [HR] = 2.12, 95% CI: 1.41-3.18), receipt of surgery (HR = 0.68, 95% CI: 0.50-0.91), chemotherapy (HR = 0.52, 95% CI: 0.35-0.78), or radiation therapy (HR = 0.55, 95% CI: 0.33-0.92) were independently associated with OS.

CONCLUSIONS

Although receipt of multimodality treatment may lead to improved survival, further research and clinical trials are required to establish best practices for the care of DSRCT.

Molecular Changes Associated With Tumor Initiation and Progression of Soft Tissue Sarcomas: Targeting the Genome and Epigenome

Soft tissue sarcomas are rare, but generally aggressive tumors which disproportionately affect children and young adults. They represent less than 10% of all cancers, but are one of the most frequently diagnosed cancers in pediatric patients. These cancers have a high rate of morbidity and mortality, and their overall incidence has been increasing at an estimated rate of 26% over the last 2 decades. The cause of this increased incidence is unknown but various environmental factors have been implicated. Establishing standard therapeutic strategies is challenging for soft tissue sarcomas as more than 50 different histological subtypes exist, each with their own molecular alterations and clinical characteristics, and this combination of tumor heterogeneity and a limited number of clinical cases make detailed omics level molecular studies particularly challenging. This chapter will focus on the unique genetic and epigenetic changes which characterize these cancers, with an emphasis on translocation-associated sarcomas involving primary gene fusions with the RNA chaperone protein EWSR1. We will highlight current therapeutic approaches and discuss opportunities for targeted molecular therapeutics.

Current management of pediatric soft tissue sarcomas

Pediatric soft tissue sarcomas are a group of malignant neoplasms arising within embryonic mesenchymal tissues during the process of differentiation into muscle, fascia and fat. The tumors have a biphasic peak for age of incidence. Rhabdomyosarcoma (RMS) is diagnosed more frequently in younger children, whereas adult-type non-RMS soft tissue sarcoma is predominately observed in adolescents. The latter group comprises a variety of rare tumors for which diagnosis can be difficult and typically requires special studies, including immunohistochemistry and molecular genetic analysis. Current management for the majority of pediatric sarcomas is based on the data from large multi-institutional trials, which has led to great improvements in outcomes over recent decades. Although surgery remains the mainstay of treatment, the curative aim cannot be achieved without adjuvant treatment. Pre-treatment staging and risk classification are of prime importance in selecting an effective treatment protocol. Tumor resectability, the response to induction chemotherapy, and radiation generally determine the risk-group, and these factors are functions of tumor site, size and biology. Surgery provides the best choice of local control of small resectable tumors in a favorable site. Radiation therapy is added when surgery leaves residual disease or there is evidence of regional spread. Chemotherapy aims to reduce the risk of relapse and improve overall survival. In addition, upfront chemotherapy reduces the aggressiveness of the required surgery and helps preserve organ function in a number of cases. Long-term survival in low-risk sarcomas is feasible, and the intensity of treatment can be reduced. In high-risk sarcoma, current research is allowing more effective disease control.

Desmoplastic small round cell tumor of the lung: A case report and literature review

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive and malignant tumor that is characterized by nests of small tumor cells surrounded by a cellular and vascular collagenous stroma and predominantly affects young adolescent males. This tumor most commonly originates in the abdomen; however, in rare cases, DSRCT can originate in other body regions. The main manifestations of DSRCT are chest pain and respiratory symptoms, and patients' average survival after diagnosis is less than two years. In this report, we describe a case involving DSRCT of the lung that proved to be difficult to diagnose, and we conduct a literature review.

Infantile pericardial round cell tumor

Cardiac malignancies presenting in infancy are rare. Desmoplastic small round cell tumor (DSRCT) is a rare occurrence in this age group. No case of intrapericardial DSRCT has been reported in the literature in infants.

Desmoplastic Small Round Cell Tumor (DSRCT): an Unusual Intra-abdominal Tumor

Desmoplastic small round cell tumor (DSRCT) is a rare intra-abdominal tumor commonly seen in adolescents and young adult males. It is an important differential diagnosis in these patients presenting with abdominal masses and/or GI obstruction. The management and prognosis improve if preoperative diagnosis can be established.

Primary desmoplastic small round cell tumor of upper cervical lymph nodes

Desmoplastic small round cell tumors (DSRCT) are rare malignancies that typically arise in the abdominopelvic cavities. They are very uncommon in the head and neck region. We present a case of an 11-year-old Caucasian male with a primary cervical lymph node tumor in the neck. Fine-needle aspiration cytology, histopathologic examination, immunohistochemical staining, and molecular genetic testing led to the diagnosis of DSRCT. Due to the very limited number of cases reported and the lack of staging criteria, the preferred management approach remains uncertain.

Imaging of pediatric desmoplastic small-round-cell tumor with pathologic correlation

Desmoplastic small-round-cell tumors are rare aggressive malignancies that belong to the "small round blue cell" tumor family. They predominantly affect the abdomen in adolescent and young adult males. Computed tomography is currently the modality of choice both for diagnosis and follow-up assessment. In this review, the authors provide a concise yet comprehensive discussion of this condition with emphasis on the imaging findings. Pathologic correlation, differential diagnostic considerations, and treatment will also be presented.

Ewing sarcoma/peripheral primitive neuroectodermal tumor and related tumors

Ewing sarcoma/peripheral primitive neuroectodermal tumor (EWS/pPNET) and other tumors with EWS gene rearrangements encompass a malignant and intermediate neoplasm with a broad anatomic distribution and a wide age range but a predilection for soft tissue in children, adolescents, and young adults. The overlapping histologic, immunohistochemical and cytogenetic and molecular genetic features create diagnostic challenges despite significant clinical and prognostic differences. Ewing sarcoma is the 3rd most common sarcoma in children and adolescents, and desmoplastic small round cell tumor is a rare neoplasm that occurs more often in older children, adolescents, and young adults. Pathologic examination is complemented by immunohistochemistry, cytogenetics, and molecular genetics. This article reviews the clinicopathologic features of EWS/pPNET and desmoplastic small round cell tumor in the spectrum of tumors with EWS gene rearrangements. Other tumors with different histopathologic features and an EWS gene rearrangement are discussed elsewhere in this volume.

Mediastinal mass-a rare presentation of desmoplastic small round cell tumour

Primary mediastinal desmoplastic small round cell cancer is an uncommon tumour usually located in the abdomen and pelvis. Here the authors report an extremely rare case of a young male with a primary desmoplastic small round cell tumour in the anterior and middle mediastinum. The patient had non-specific complaints but an abnormal shadow was seen in a routine chest x-ray. He was diagnosed as having mediastinal mass with few lung parenchymal deposits on CT. Mediastinoscopy and guided biopsy revealed desmoplastic small round cell tumour. Desmoplastic small round cell tumour is a rare and aggressive tumour which rarely involves the mediastinum as a primary site. The nature of the lesion and its prognosis were explained to the patient. He was offered chemotherapy and radiotherapy for the tumour management. He refused treatment and left against medical advice.

A rapidly developing lung mass diagnosed as desmoplastic small round cell tumor

We present a case of a young male who presented with complaints of fever along with cough and sputum. He was diagnosed with having right pleural effusion. He was already taking anti-tubercular therapy for one month before presentation. He was started on intravenous antibiotics and continued on anti-tubercular therapy in our hospital, based on his high leukocyte count, pleural fluid analysis, and ultrasonographic report of multiple hypoechoic areas in the liver. His symptoms continued to worsen and he subsequently developed mediastinal widening and a left lung mass. Commuted tomography (CT)-guided biopsy of the lung mass revealed a desmoplastic small-round-cell tumor. Desmoplastic small-round-cell tumor is a rare and aggressive tumor, which presents rarely as a mediastinal and lung mass. This tumor has very poor prognosis.

An unusual presentation of desmoplastic small round cell tumour of the abdomen: morphological, immunohistochemical, ultrastructural, and molecular studies

Desmoplastic small round cell tumour (DSRCT) is an aggressive and a rare neoplasm. We report on a 34-year-old male who had abdominal discomfort with a large intraperitoneal mass. Histological examination of the tumour biopsy revealed sheets of small round cells. The cells were positive with vimentin and desmin (with occasional dot positivity) and negative for WT1 and CD 99 with immunohistochemistry. Cytogenetics showed a translocation disrupting the EWSR 1 gene on 22 q 12 consistent with DSRCT. Electron microscopic examination showed sparse cytoplasmic organelles. The patient succumbed 34 months from disease presentation after multiple chemotherapies and thereafter radiotherapy. In summary, our case exemplifies that it is crucial to combine clinical, histological, and molecular aspects in diagnosing DSRCT especially when characteristic dot positivity with desmin is weak along with deficient marking of WT1 and CD99 by immunohistochemistry. Histology was also less clear than published examples of this entity with a poor desmoplastic response. A multidisciplinary approach including early referral to specialised centres is recommended in these cases as tertiary referral centres will be required to substantiate the diagnosis.