Desmoplastic small round cell tumor presenting as a neck mass: a case report

EWSR1::WT1 Fusions in Neoplasms Other Than Conventional Desmoplastic Small Round Cell Tumor: Three Tumors Occurring Outside the Female Genital Tract

Desmoplastic small round cell tumor (DSRCT) is a high-grade, primitive round cell sarcoma classically associated with prominent desmoplastic stroma, coexpression of keratin and desmin, and a characteristic EWSR1::WT1 gene fusion. DSRCT typically arises in the abdominopelvic cavity of young males with diffuse peritoneal spread and poor overall survival. Although originally considered to be pathognomonic for DSRCT, EWSR1::WT1 gene fusions have recently been detected in rare tumors lacking the characteristic morphologic and immunohistochemical features of DSRCT. Here, we report 3 additional cases of neoplasms other than conventional DSCRCT with EWSR1::WT1 gene fusions that occurred outside the female genital tract. Two occurred in the abdominopelvic cavities of a 27-year-old man and a 12-year-old girl, whereas the third arose in the axillary soft tissue of an 85-year-old man. All cases lacked prominent desmoplastic stroma and were instead solid and cystic with peripheral fibrous pseudocapsules and occasional intervening fibrous septa. Necrosis was either absent (1/3) or rare (2/3), and mitotic activity was low (<1 to 3 per 10 hpf). In immunohistochemical studies, there was expression of smooth muscle actin (3/3) and desmin (3/3), rare to focal reactivity for EMA (2/3), and variable expression of CK AE1/AE3 (1/3). Myogenin and MyoD1 were negative, and C-terminus-specific WT1 was positive in both cases tested (2/2). All 3 tumors followed a more indolent clinical course with 2 cases demonstrating no evidence of disease at 20 and 44 months after resection. The patient from case 3 died of other causes at 14 months with no evidence of recurrence. DNA methylation profiling showed that the 3 cases clustered with DSRCT; however, they demonstrated fewer copy number variations with 2 cases having a flat profile (0% copy number variation). Differential methylation analysis with hierarchical clustering further showed variation between the 3 cases and conventional DSRCT. Although further study is needed, our results, in addition to previous reports, suggest that EWSR1::WT1 gene fusions occur in rare and seemingly distinctive tumors other than conventional DSRCT with indolent behavior. Proper classification of these unusual soft tissue tumors with EWSR1::WT1 gene fusions requires direct correlation with tumor morphology and clinical behavior, which is essential to avoid overtreatment with aggressive chemotherapy.

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 of the Kidney: Report of a Case, Literature Review, and Comprehensive Discussion of the Distinctive Morphologic, Immunohistochemical, and Molecular Features in the Differential Diagnosis of Small Round Cell Tumors Affecting the Kidney

Desmoplastic small round cell tumor (DSRCT) is a rare, highly aggressive neoplasm typically presenting with widespread involvement of the abdominopelvic peritoneum of adolescent males, usually without organ-based primary. Although it is believed to originate from the serous (mainly peritoneal) membranes, intracranial, sinonasal, intraosseous, and other soft tissue sites are also documented. A chromosomal translocation t(11:22)(p13;q12) signature that fuses EWSR1 and WT1 genes results in the production of a chimeric protein with transcriptional regulatory activity that drives oncogenesis. Integration of clinical, morphologic, immunohistochemical, and genetic data is necessary to arrive at the correct diagnosis, especially when the tumor arises in an atypical site. A 15-year-old male presented with hematuria and was found to have a large renal tumor associated with adrenal, liver, lung, and bone metastases. Histopathologic and immunophenotypic features were distinctive for DSRCT. This diagnosis was confirmed by means of fluorescence in situ hybridization and cytogenetic analysis, which documented the pathognomonic t(11;22) translocation, and by reverse transcription polymerase chain reaction on snap-frozen tissue, which revealed the EWSR1/WT1-specific chimeric transcript. Despite high-dose chemotherapy and radiation therapy targeted to a single T11 vertebral metastasis, the disease progressed, and the patient died 4 years after the diagnosis. A search of electronic databases for DSRCT yielded 16 cases of well-documented renal primaries out of around 1570 cases from all sites gathered from the global literature. Desmoplastic small round blue cell tumor and other primary renal tumors considered in the differential diagnosis with DSRCT are discussed.

A comprehensive diagnosis of a desmoplastic small round cell tumor of unusual location based on fine-needle aspiration cytology: Report of a case arising in the parotid gland and review of the literature

Desmoplastic small round cell tumor (DSRCT) is rare and a highly aggressive neoplasm that typically involves the soft tissues of the abdomen or pelvis in children or young adults, showing a male predilection. Although it can occurs over a wide age range, the peak incidence is in the third decade of life. DSRCT usually shows widespread abdominal serosal involvement, and overall patient survival is poor. On the other hand, extra-abdominal DSRCT is very rare. DSRCT in major salivary glands has been reported, but it is extremely rare. In the majority of reported series diagnosis is made by the histological analysis of FFPE tissues together with immunohistochemistry (IHC) and molecular analysis, particularly the demonstration of chromosomal translocation involving EWSR1. Very few cases have been diagnosed so far by Fine Needle Aspiration (FNA) cytology. Moreover ancillary studies have been performed in all reported cases in FFPE samples. There is still controversy and lack of consensus regarding the suitability of cytological samples especially smears for immunocytochemical (ICC) and fluorescence in situ hybridization (FISH), what makes its standardization difficult. We report a case of a primary DSRCT of parotid gland in a 17-year-old male diagnosed by FNA cytology. The cytomorphological diagnosis was coupled with ICC and FISH analysis performed on stained smears. We emphasize the feasibility and reliability of cytological smears for the application of immunocytochemical and molecular techniques.

Soft Tissue Special Issue: Adamantinoma-Like Ewing Sarcoma of the Head and Neck: A Practical Review of a Challenging Emerging Entity

Adamantinoma-like Ewing sarcoma (ALES) is a rare variant of Ewing sarcoma that is defined by complex epithelial differentiation, including expression of cytokeratin and p40 and frequent keratin pearl formation. In recent years, ALES has been increasingly recognized in the head and neck, where it can mimic a wide range of small round blue cell tumors and basaloid carcinomas. However, there has been persistent controversy regarding whether ALES is best classified and managed as a sarcoma or carcinoma. This review summarizes the characteristic clinical, pathologic, immunophenotypic, and molecular features of ALES with an emphasis on differential diagnosis and tumor classification.

Desmoplastic Small Round Cell Tumor: Imaging Pattern of Disease at Presentation

OBJECTIVE

The purpose of this study is to evaluate the clinical, pathologic, and multimodality cross-sectional imaging features of a cohort of 94 patients with desmoplastic small round cell tumor (DSRCT).

MATERIALS AND METHODS

This retrospective study of 94 patients with pathologically verified DSRCT was conducted at a tertiary cancer center between 2001 and 2013. Epidemiologic, clinical, pathologic, and imaging findings were recorded. Tumor size, location, and shape and the distribution pattern of metastases at presentation were analyzed.

RESULTS

DSRCT most often occurred in young patients (median age, 21.5 years; range, 5-53 years), showing a marked predominance in male patients (86 male patients vs eight female patients). Eighty nine-patients (95%) were white (defined in this study as white or Hispanic), four were African American, and one was of Asian descent. Most patients had symptoms, with abdominal pain noted as the most common symptom. At initial presentation, 85 patients (90%) had multifocal disease, nodular disease, diffuse omental and peritoneal disease, or a combination of these conditions. Thirty-eight patients (40%) had diaphragmatic involvement. Thirty-two patients (34%) had liver metastases, and 49 patients (52%) had retroperitoneal involvement in the form of implants, tumoral extension, or nodal involvement. With regard to thoracic findings, 33 patients (35%) had nodal disease, 17 (18%) had pleural effusions, and only two (2%) had lung metastases at presentation. Twelve patients (13%) had calcified lesions.

CONCLUSION

DSRCT is a rare, multifocal peritoneal malignancy with frequently disseminated abdominal disease at presentation. In the abdomen, disease most commonly involves the omentum and peritoneum, followed by the retroperitoneum. The liver is the most common solid visceral metastatic site. A substantial number of patients have diaphragmatic involvement. In the thorax, nodal and pleural involvement is more common than lung involvement.

Adamantinoma-like Ewing family tumors of the head and neck: a pitfall in the differential diagnosis of basaloid and myoepithelial carcinomas

Ewing sarcoma family tumors (EFTs) of the head and neck are rare and may be difficult to diagnose, as they display significant histologic overlap with other more common undifferentiated small blue round cell malignancies. Occasionally, EFTs may exhibit overt epithelial differentiation in the form of diffuse cytokeratin immunoexpression or squamous pearls, resembling the so-called adamantinoma-like EFTs and being challenging to distinguish from bona fide carcinomas. Furthermore, the presence of EWSR1 gene rearrangement correlated with strong keratin expression may suggest a myoepithelial carcinoma. Herein, we analyze a series of 7 adamantinoma-like EFTs of the head and neck, most of them being initially misdiagnosed as carcinomas because of their anatomic location and strong cytokeratin immunoexpression, and subsequently reclassified as EFT by molecular techniques. The tumors arose in the sinonasal tract (n=2), parotid gland (n=2), thyroid gland (n=2), and orbit (n=1), in patients ranging in age from 7 to 56 years (mean, 31 y). Microscopically, they departed from the typical EFT morphology by growing as nests with peripheral nuclear palisading and prominent interlobular fibrosis, imparting a distinctly basaloid appearance. Moreover, 2 cases exhibited overt keratinization in the form of squamous pearls, and 1 sinonasal tumor demonstrated areas of intraepithelial growth. All cases were positive for CD99, pancytokeratin, and p40. A subset of cases showed synaptophysin, S100 protein, and/or p16 reactivity, further confounding the diagnosis. Fluorescence in situ hybridization assays showed EWSR1 and FLI1 rearrangements in all cases. Our results reinforce that a subset of head and neck EFTs may show strong cytokeratin expression or focal keratinization, and are therefore histologically indistinguishable from more common true epithelial neoplasms. Thus, CD99 should be included in the immunopanel of a round cell malignancy regardless of strong cytokeratin expression or anatomic location, and a strong and diffuse CD99 positivity should prompt molecular testing for the presence of EWSR1 gene rearrangements.

Myeloablative chemotherapy with autologous stem cell transplant for desmoplastic small round cell tumor

Desmoplastic small round cell tumor (DSRCT), a rare, aggressive neoplasm, has a poor prognosis. In this prospective study, we evaluated the role of myeloablative chemotherapy, followed by autologous stem cell transplant in improving survival in DSRCT. After high-dose induction chemotherapy and surgery, 19 patients with chemoresponsive DSRCT underwent autologous stem cell transplant. Myeloablative chemotherapy consisted of carboplatin (400–700 mg/m²/day for 3 days) + thiotepa (300 mg/m²/day for 3 days) ± topotecan (2 mg/m²/day for 5 days). All patients were engrafted and there was no treatment-related mortality. Seventeen patients received radiotherapy to sites of prior or residual disease at a median of 12 weeks after transplant. Five-year event-free and overall survival were 11 ± 7% and 16 ± 8%, respectively. Two patients survive disease-free 16 and 19 years after transplant (both in complete remission before transplant). 14 patients had progression and died of disease at a median of 18 months following autologous transplant. These data do not justify the use of myeloablative chemotherapy with carboplatin plus thiotepa in patients with DSRCT. Alternative therapies should be considered for this aggressive neoplasm.

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.

Fine-needle aspiration in desmoplastic small round cell tumor: a report of 10 new tumors in 8 patients with clinicopathological and molecular correlations with review of the literature

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is a rare round cell sarcoma entity characterized by a specific t(11;22)(p13;q12) translocation, usually intra-abdominal localization and an aggressive clinical outcome. To date, only 35 DSRCT cases diagnosed by fine-needle aspiration have been described.

METHODS

This study reports the cytological diagnosis of DSRCT. Ten tumors from 8 patients were sampled for diagnosis and analyzed to search the characteristic translocation using fluorescence in situ hybridization or reverse transcription polymerase chain reaction methods.

RESULTS

Smears were always hypercellular and consisted of nonspecific round cell sarcoma. Nuclei were polymorphic round, kidney-, or heart-shaped. Nuclear molding was usually present. Paranuclear cytoplasmic densities were obvious and noted in 7 cases. Cytonuclear atypia, mitotic figures, numerous crushed nuclei, and apoptosis were frequently seen. Purple-stained stroma was present in 8 cases (ranging from few connective tissue fragments to large hyalinized deposits). Molecular studies based on cytological aspirates were performed in 8 patients. The presence of the fusion gene EWSR1-WT 1 transcript was identified in all, which confirmed the diagnosis of DSRCT.

CONCLUSIONS

Smears showing poorly differentiated round cells associated with cytoplasmic densities and connective stoma, in a specific clinical context, young adult age, intra-abdominal localization, suggestive immunocytochemical profile, and a unique cytogenetic abnormality are highly specific and allow an accurate diagnosis of DSRCT.

Desmoplastic small round cell tumors with EWS-WT1 fusion transcript in children and young adults

BACKGROUND

The presence of the EWS-WT1 gene fusion transcript (GFT) is characteristic of desmoplastic small round cell tumor (DSRCT), a rare and very aggressive disease for which the treatment has not yet been clearly standardized.

METHODS

This was a retrospective national multicenter analysis of young patients <30 years with tumors expressing the EWS-WT1-GFT, designed to determine whether extensive surgery had an impact on survival.

RESULTS

Between 1995 and 2006, a EWS-WT1-GFT was detected in the tumors of 38 patients, 17 (44.7%) of whom had had a different initial pathologic diagnosis prior to molecular testing. Mean age was 13.2 years (range: 4-29.7 years). Only 9 patients (24%) had localized disease. Treatment was heterogeneous. Nine patients had "limited" surgical resections and 22 underwent "extensive" surgery. Two-year event-free survival and overall survival were 14.4% and 50%, respectively. Among the five patients who were alive in complete remission, four had undergone extensive and complete surgery.

CONCLUSIONS

Detection of the EWS-WT1-GFT plays a major role in the diagnosis of DSRCT. No survival difference was observed according to extent of surgery, but complete surgery seemed to offer the best chance of long-term survival. High-dose chemotherapy or local radiotherapy did not appear to improve survival in this retrospective analysis, but larger prospective studies are needed to provide definitive conclusions on the role of these treatments.

Intra-abdominal desmoplastic small round cell tumors: CT findings and clinicopathological correlations in 13 cases

PURPOSE

We report computed tomography (CT) findings in 13 patients with a primary abdominal desmoplastic small round cell tumor.

MATERIALS AND METHODS

13 cases (12 men, 1 woman, mean age=24.8 years) were found in our hospital database between 1991 and 2003. Clinical, CT and histopathological features were studied retrospectively.

RESULTS

Peritoneal involvement was the most common feature. In 10 cases, several lobulated peritoneal soft tissue masses (with a mean of four masses per patient) were seen. Two patients had diffused irregular peritoneal carcinomatosis without any distinct peritoneal masses. One patient had a solitary mass in the pelvic space. The main sites of peritoneal involvement were the pelvic space (n=7), omentum (n=5), retroperitoneal space (n=4), small bowel mesentery (n=3), paracolic gutter (n=2 on the right and n=1 on the left), transverse colon mesentery (n=1), peri-splenic space (n=1), peri-hepatic space (n=1). The soft tissue masses were often bulky (mean 6cm, range 1-28cm), lobulated and heterogeneous with hypodense areas (in 73% of cases). In six cases, moderate ascites was seen. In one case of pelvic involvement, unilateral hydronephrosis was seen. Adenopathies were present in seven cases at the time of the diagnosis (at intraperitoneal, retroperitoneal and pelvic sites in six patients and in the groin in one patient). Five patients had liver metastases (four lesions per case excepted one patient with 30 metastases). Associated thoracic metastases were seen in three patients. The diagnosis was confirmed with four CT-guided percutaneous biopsies.

CONCLUSION

Although CT features are nonspecific, the diagnosis of desmoplastic small round cell tumor may be suspected in young men with multiple bulky heterogeneous peritoneal soft tissue masses. Imaging is useful for staging and also to guide biopsies.

Establishment and characterization of a novel human desmoplastic small round cell tumor cell line, JN-DSRCT-1

The exact nature of the desmoplastic small round cell tumor (DSRCT) remains controversial. More detailed analyses might be facilitated by the establishment of permanent DSRCT cell lines. To date, however, no human DSRCT cell line has been reported. In this study, we report the establishment of a new human cell line, JN-DSRCT-1, from the pleural effusion of a 7-year-old boy with pulmonary metastasis from a typical intra-abdominal DSRCT. JN-DSRCT-1 cells were small round or spindle shaped with oval nuclei and have been maintained continuously in vitro for over 190 passages during more than 40 months. Histologic features of the heterotransplanted tumors in severe combined immunodeficiency mouse were essentially the same as those of the original DSRCT, revealing nests or clusters of small round cells embedded in an abundant desmoplastic stroma. Both in vitro and in vivo, the cells exhibited immunopositive reactions for vimentin, desmin, cytokeratins (AE1/AE3 and CAM 5.2), epithelial membrane antigen, neuron-specific antigen, and CD57 (Leu-7). JN-DSRCT-1 cells exhibited a pathognomonic t(11;22)(p13;q12) translocation by cytogenetic analysis. In addition, RT-PCR and sequencing analysis revealed a chimeric transcriptional message of the Ewing's sarcoma gene exon 10 fused to the Wilms' tumor gene exon 8. To our knowledge, this is the first permanent human DSRCT cell line. The JN-DSRCT-1 cell line, which exhibits the unique morphologic and genetic characteristics of DSRCT, will be extremely useful for a variety of important studies such as the pathogenic mechanism, biologic behavior, and therapeutic model of human DSRCT.