The expanding clinical spectrum of desmoplastic small round-cell tumor: a report of two cases with molecular confirmation

Desmoplastic Small Round Cell Tumor of the Head and Neck: A Potential Diagnostic Pitfall

Primary desmoplastic small round cell tumor (DSRCT) in the head and neck region is extremely rare. There is limited information about its clinicopathological characteristics, prognosis, and treatment modalities. The purpose of this study is to provide a comprehensive review of DSRCT occurring primarily in the head and neck, to demonstrate its peculiar morphology and immunohistochemical expression, and to address the differential diagnoses. A total of 25 cases were collected after a thorough review of the relevant literature. DSRCT was most frequently reported in the major salivary glands, followed by the eyes. Furthermore, some cases were misinterpreted as poorly differentiated carcinoma, Ewing sarcoma, and olfactory neuroblastoma. Diagnosing DSRCTs in the head and neck can be very challenging due to their rarity in this location, overlapping morphology, and immunohistochemistry. In these cases, following a systemic approach helps to solve diagnostic problems.

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.

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.

Adamantinoma-Like Ewing Sarcoma of the Parotid Gland: Report of Two Cases and Review of Literature

Adamantinoma-like Ewing sarcoma (ALES) is a rare variant of Ewing sarcoma. It demonstrates heterogeneous morphologic pattern and complex immunophenotypic profile, with a peculiar combination of epithelial and neuroendocrine differentiation. ALES is rarely reported in the head and neck areas, including the parotid salivary gland. Till now, only 10 cases of ALES have been reported in the salivary glands. Herein, we report two cases of ALES involving the parotid gland, adding some valuable insight to the recently reported cases at this site.

Desmoplastic Small Round Cell Tumor: A Rare Location in the Parotid Gland

Desmoplastic small round cell tumor represents an unusual variety of tumors that affects mostly children and young males. In this report we present a case of a desmoplastic small round cell tumor involving the parotid gland of a young male. The tumor was excised, and definitive histology showed features of desmoplastic small round cell tumor confirming the diagnosis.

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.

Desmoplastic Small Round Cell Tumor of Parotid Gland: A Rare Entity With Diagnostic Challenge

Desmoplastic small round cell tumor (DSRCT) is a rare malignant mesenchymal neoplasm that typically affects young patients and presents as large intraabdominal masses. We report a rare case of parotid gland DSRCT in a 38-year-old man. The tumor cells were large sized and form irregular nests embedded in abundant desmoplastic stroma. Immunohistochemically, the tumor cells were positive for cytokeratin, GATA3, p40, and p63. Working differential diagnosis included squamous cell carcinoma, myoepithelial carcinoma, hyalinizing clear cell carcinoma, NUT (nuclear protein of the testis) carcinoma, and adamantinoma-like Ewing sarcoma. The characteristic morphologic features and presence of EWSR1-WT1 gene fusion are diagnostic of DSRCT. Salivary gland DSRCT is an exceedingly rare entity, with only 6 cases reported in the literature.

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 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.

Desmoplastic small round cell tumor: evaluation of reverse transcription-polymerase chain reaction and fluorescence in situ hybridization as ancillary molecular diagnostic techniques

Desmoplastic small round cell tumor (DSRCT) is a rare, biologically aggressive soft tissue neoplasm of uncertain differentiation, most often arising in the abdominal and pelvic cavities of adolescents and young adults with a striking male predominance. Histologically, it is characterized by islands of uniform small round cells in prominent desmoplastic stroma, and it has a polyimmunophenotypic profile, typically expressing WT1 and cytokeratin, desmin, and neural/neuroendocrine differentiation markers to varying degrees. Tumors at other sites and with variant morphology are more rarely described. DSRCT is associated with a recurrent t(11;22)(p13;q12) translocation, leading to the characteristic EWSR1-WT1 gene fusion. Fluorescence in situ hybridization (FISH), to detect EWSR1 rearrangement, and reverse transcription-polymerase chain reaction (RT-PCR) to assess for EWSR1-WT1 fusion transcripts are routine diagnostic ancillary tools. We present a large institutional comparative series of FISH and RT-PCR for DSRCT diagnosis. Twenty-six specimens (from 25 patients) histologically diagnosed as DSRCT were assessed for EWSR1 rearrangement and EWSR1-WT1 fusion transcripts. Of these 26 specimens, 24 yielded positive results with either FISH or RT-PCR or both. FISH was performed in 23 samples, with EWSR1 rearrangement seen in 21 (91.3%). RT-PCR was performed in 18 samples, of which 13 (72.2%) harbored EWSR1-WT1 fusion transcripts. The sensitivity of FISH in detecting DSRCT was 91.3%, and that of RT-PCR was 92.8% following omission of four technical failures. Therefore, both methods are comparable in terms of sensitivity. FISH is more sensitive if technical failures for RT-PCR are taken into account, and RT-PCR is more specific in confirming DSRCT. Both methods complement each other by confirming cases that the other method may not. In isolation, FISH is a relatively non-specific diagnostic adjunct due to the number of different neoplasms that can harbor EWSR1 rearrangement, such as Ewing sarcoma. However, in cases with appropriate morphology and a typical pattern of immunostaining, FISH is confirmatory of the diagnosis.

A Biphasic Pleural Tumor with Features of an Epithelioid and Small Cell Mesothelioma: Morphologic and Molecular Findings

Malignant mesotheliomas are generally classified into epithelioid, sarcomatoid, desmoplastic, and biphasic types with rare reports of a small cell form. These small cell variants display some morphologic overlap with desmoplastic small round cell tumors (DSRCTs) which generally occur within the abdominal cavity of young males and are defined by a characteristic t(11;22)(p13;q12) translocation. However, there are rare reports of DSRCTs lacking this translocation. We present a 78-year-old man with a pleura-based biphasic neoplasm with features of both epithelioid mesothelioma and a small cell blastema-like neoplasm. The epithelioid portion showed IHC reactivity for pan cytokeratin, CK5/6, D2-40, and calretinin and the small cell portion marked with CD99, pan cytokeratin, WT1, FLI1, S100, CD200, MyoD1, and CD15. Fluorescence in situ hybridization testing for the t(11;22)(p13;q12) translocation disclosed loss of the EWSR1 gene in 94% of tumor cell nuclei, but there was no evidence of the classic translocation. Array based-comparative genomic hybridization (a-CGH) confirmed the tumor had numerous chromosome copy number losses, including 11p15.5-p11.12 and 22q12.1-q13.33, with loss of the EWSR1 and WT1 gene regions. Herein, we report novel complex CGH findings in a biphasic tumor and review the molecular genetic alterations in both mesothelioma and DSRCTs.

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.

Adamantinoma-like Ewing sarcoma mimicking basal cell adenocarcinoma of the parotid gland: a case report and review of the literature

Adamantinoma-like Ewing sarcoma (AES) is a rare variant of the Ewing family of tumors that resembles classic adamantinoma of bone. AES shows epithelial differentiation and a more complex immunohistochemical expression profile with keratin and basal marker immunoreactivity and can resemble a variety of carcinomas. We report an unusual case of an AES of the parotid gland that mimicked a basal cell adenocarcinoma. Like basal cell adenocarcinoma, this AES showed a nested basaloid proliferation with peripheral palisading in tumor nests with 'basaloid' epithelial differentiation as highlighted by cytokeratin AE1/3 and p40 positivity. However, unlike most basal cell adenocarcinomas, this tumor demonstrated high grade morphology, showed no true ductal or myoepithelial component, and also showed a tendency towards neuroectodermal phenotype with focal rosette formation, CD99 and weak synaptophysin immunoreactivity. EWSR1 and FLI1 fluorescence in situ hybridization confirmed the presence of a translocation supporting the diagnosis of AES. This is the first case of AES presenting as a primary parotid mass highlighting the potential to be mistaken for primary salivary gland carcinomas, which in addition to basal cell adenocarcinoma include other basaloid tumors such as adenoid cystic carcinoma.

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.

Desmoplastic small round cell tumor with atypical immunohistochemical profile and rhabdoid-like differentiation

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive malignant neoplasm of unknown origin, and is comprised of small round cells with a characteristic desmoplastic stroma. DSRCT typically expresses epithelial, mesenchymal and neural markers simultaneously. We describe a case of DSRCT with an atypical immunohistochemical profile and rhabdoid-like tumor cells on electron microscopy. In the present case, the neoplastic cells were positive only for vimentin, desmin (cytoplasmic membranous pattern) and CD56, and negative for smooth muscle actin, synaptophysin, CD117, CD45, myogenin, CAM5.2, pancytokeratin, WT1, EMA, CD99, neurofilament, CD34 and p53. Ki67 showed a low proliferative activity. Electron microscopy showed focal rhabdoid differentiation. However, INI-1 (SNF-5/BAF47) demonstrated preservation of nuclear positivity in the neoplastic cells. Cytogenetic studies showed translocation t(11;22)(p13;q12) confirming an EWSR1-WT1 translocation characteristic for DSRCT, and t(1;15)(q11;p11.2) of unknown significance. This case is a diagnostic challenge because of atypical immunohistochemical profile and cytogenetic study is crucial in rendering the correct diagnosis.

Primary sarcomas of the salivary glands: case series and literature review

BACKGROUND

Mesenchymal malignancies of salivary origin are rare and are histologically diverse. We reviewed our experience with these tumors, as well as the published literature, with an emphasis on treatment modalities and prognosis.

METHODS

We identified 17 patients treated for malignant mesenchymal cell tumors at The University of Texas MD Anderson Cancer Center between 1990 and 2007. We compared our results to the literature from January 1990 to July 2010.

RESULTS

Tumors were located primarily in the parotid gland and were primarily T1 tumors (<5 cm). All patients were treated with surgical resection, and 13 patients were given adjuvant therapy. Seven patients (41%) had recurrence, and 4 developed distant metastases. The overall 5-year and 10-year survival rates were 42% and 20%, respectively.

CONCLUSIONS

Our case series and literature review show that sarcomas of the salivary glands have a high rate of recurrence and are associated with a poor prognosis.

Desmoplastic small round cell tumor of stomach

Desmoplastic small round cell tumor (DSRCT) is an extremely uncommon, highly aggressive, and malignant mesenchymal neoplasm of undetermined histogenesis. Less than 200 case reports have been documented in literature so far. Herein, we report a 26-year-old otherwise healthy female patient who presented with a 1-month history of epigastric pain. On physical examination, a palpable, slightly mobile, and tender epigastric mass was detected. All laboratory tests were normal. A chest, abdominal, and pelvic contrast-enhanced computed tomography (CT) scans showed a 3.8 × 7.2 × 8.7 cm ill-defined mass, involving gastric fundus and extending into gastric cardia and lower gastroesophageal junction. It was associated with multiple enlarged gastrohepatic lymph nodes; the largest measured 1.2 cm. There was no evidence of ascites or retroperitoneal or mesenteric lymphatic metastases. Patient underwent total gastrectomy with D2 lymphadenectomy, splenectomy, and antecolic Roux-en-Y esophagojejunal anastomosis. Histopathological examination revealed coexpression of mesenchymal, epithelial, and neural markers. The characteristic chromosomal translocation (t(11; 22)(p13; q12)) was demonstrated on fluorescence in situ hybridization (FISH) technique. Diagnosis of DSRCT of stomach was confirmed. Patient received no postoperative radiotherapy or chemotherapy. A postoperative 3-month followup failed to show any recurrence. In addition, a literature review on DSRCT is included.

Desmoplastic small round cell tumor (DSRCT) xenografts and tissue culture lines: Establishment and initial characterization

Desmoplastic small round cell tumor (DSRCT) is an extremely rare and aggressive neoplasm, which mainly affects young males and generally presents as a widely disseminated tumor within the peritoneal cavity. Due to the rarity of the tumor, its younger and overall healthier patient population (compared with other tumor types) and the fact that it lacks definitive histological and immunohistological features, the diagnosis of DSRCT may be frequently delayed or the tumor may be entirely misdiagnosed as a different type of abdominal sarcoma. The present study aimed to rectify the lack of models that exist for this rare neoplasm, through the development of several DSRCT tissue cultures and xenograft lines. Samples were received from surgeries and biopsies from patients worldwide and were immediately processed for xenograft development in nude mice. Tumor tissues were minced and fragments were injected into the dorsal flanks of nude mice. Of the 14 samples received, nine were established into xenograft lines and five into tissue culture lines. Xenografts displayed the microscopic histology of their parent tumors and demonstrated two different growth rates among the established xenograft lines. Overall, the establishment of these xenograft and tissue culture lines provides researchers with tools to evaluate DSRCT responses to chemotherapy and to investigate DSRCT-specific signaling pathways or mechanisms.

Clinicopathological investigation of four cases of desmoplastic small round cell tumor

The purpose of this study was to perform clinicopathological and immunohistochemical analysis and to investigate the Ewing sarcoma gene (EWS)-Wilms' tumor suppressor gene (WT1) fusion within desmoplastic small round cell tumors (DSRCTs). Histology slides and clinical data were reviewed for four patients with DSRCT. A variety of immunohistochemical staining was performed. Fluorescence in situ hybridization (FISH) was performed to detect the EWS-WT1 fusion transcripts resulting from the chromosomal translocation t(11;22)(p13;q12). The patients consisted of four males aged from 26 to 52 years old (mean, 33.5). In three of these patients, the tumors were situated in the abdominal cavity and the tumor from the other patient was located in the pelvic cavity. The tumors were 8-15 cm in diameter (mean tumor diameter, 13), solid and gray-white, with an appearance of nodosity or sublobes, and hemorrhage or necrosis was observed. Microscopically, the tumors consisted of small round cell nests of unequal size. Hyperplastic and thick fibrous connective tissue surrounding the neoplastic cell nests was present in all cases. The tumor nuclei were hyperchromatic and contained inconspicuous nucleoli with a high level of karyokinesis. Immunohistochemical staining revealed diffuse and strong staining for CK, vimentin, desmin and CAM5.2 in all cases. Certain cases also expressed WT-1, EMA, NSE, CD56, CD99 and CK5/6. Staining was negative for myogenin, MyoD1, calretinin, CD117, CD34, HMB45 and CEA. EWS-WT1 fusion transcripts were detected in 3 out of 4 cases, but not in any other tumor types studied as controls using paraffin-embedded tissue by FISH. DSRCT is a highly maligant tumor occuring predominantly in the abdominal or pelvic cavity of young males with multiphenotypic differentiation. Basic morphological features, clinical manifestations and the detection of the EWS-WT1 fusion transcript within the tumor aid the recognition and diagnosis of the tumor.

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.

Soft tissue tumors associated with EWSR1 translocation

The Ewing sarcoma breakpoint region 1 (EWSR1; also known as EWS) represents one of the most commonly involved genes in sarcoma translocations. In fact, it is involved in a broad variety of mesenchymal lesions which includes Ewing's sarcoma/peripheral neuroectodermal tumor, desmoplastic small round cell tumor,clear cell sarcoma, angiomatoid fibrous histiocytoma, extraskeletal myxoid chondrosarcoma, and a subset of myxoid liposarcoma. The fusion products between EWSR1 and partners usually results in fusion of the N-terminal transcription-activating domain of EWSR1 and the C-terminal DNA-binding domain of the fusion partner, eventually generating novel transcription factors. EWSR1 rearrangement can be visualized by the means of fluorescence in situ hybridization (FISH). As soft tissue sarcomas represent a diagnostically challenging group, FISH analysis is an extremely useful confirmatory diagnostic tool. However, as in most instances a split-apart approach is used, the results of molecular genetics must be evaluated in context with morphology.

Sialoblastoma: utility of Ki-67 and p53 as a prognostic tool and review of literature

Sialoblastoma is a rare tumor of the salivary gland that commonly occurs in the parotid gland and occasionally in the sub-mandibular gland. The malignant potential of sialoblastoma has been documented in only 3 of 32 cases of sialoblastoma reported thus far. In the last 15 years, we have encountered 2 cases of sialoblastoma, in a newborn and in a 15-year-old boy, both arising within the parotid gland. Case 1 has been previously reported and although there were 2 recurrences, at 1 and 9 years post resection, it has shown benign biological behavior. Case 2 is unusual since the patient presented with metastases. We reviewed the 2 cases, including the 2 recurrences from the first case, for histologic and immunohistochemical differences. Although both cases showed similar cytomorphologic features, there was a significant difference in Ki-67 expression: 20% in case 1 (original tumor), <2% in case 1 (recurrent tumor), and nearly 70-80% in the recent malignant case. The difference is remarkable when combined with p53 expression, which was focally positive in the first case but diffusely positive in the second. This report highlights the potential utility of proliferation markers such as Ki-67 in concert with p53 expression to better predict the biological behavior of a rare but locally aggressive neoplasm.

Desmoplastic small round cell tumor of the submandibular gland--a rare but distinctive primary salivary gland neoplasm

Desmoplastic small round cell tumor is a highly aggressive neoplasm that generally involves the peritoneum and pelvis of young patients. Only rare cases occur outside the abdomen. We report a case presenting as a primary submandibular gland tumor in a 24-year-old man. Histologically, although there were irregular tumor islands lying in an abundant desmoplastic stroma, there were also areas comprising large cellular islands with scanty stroma in between, raising the differential diagnosis of various salivary gland carcinomas. The tumor cells were medium sized, with hyperchromatic nuclei and moderate amounts of cytoplasm. The diagnosis of desmoplastic small round cell tumor was confirmed by the presence of a polyphenotypic immunoprofile (positive for cytokeratin, desmin, and neuron-specific enolase) and the characteristic EWS-WT1 gene fusion. Although rare, desmoplastic small round cell tumor has to be considered in the differential diagnosis of poorly differentiated neoplasms of the salivary gland, especially in young patients.

Desmoplastic small round cell tumor of the central nervous system: report of two cases and review of the literature

Desmoplastic small round cell tumor (DSRCT) is a malignant tumor often involving the abdominal and/or pelvic peritoneum. Only one fully documented example has arisen in the central nervous system (CNS). Herein, we describe two additional examples, fulfilling the morphologic, immunohistochemical, and molecular criteria (EWS/WT1 translocation) of DSRCT. Both arose in the cerebellopontine angle (CPA) and underwent spinal dissemination. Patient 1, a 37-year-old male, underwent a subtotal resection, and 2 years later died of recurrent disease with spinal dissemination. Patient 2, a 39-year-old man, presented with cerebellar and CPA lesions as well as spinal leptomeningeal deposits. After 27 months of adjuvant therapy, he is alive with progressive disease. In conclusion, CNS DSRCT follows a similar aggressive course as do peritoneal examples. Although rare, DSRCT warrants consideration in the differential diagnosis of "malignant small blue cell tumors" of the CNS.

Intracerebral small round cell tumor: an unusual case with EWS-WT1 translocation

Desmoplastic small round cell tumor (DSRCT) is a rare tumor, seen both in children and young adults with a marked predilection for the peritoneal cavity. Histology showed a small round cell tumor with a fibromyxoïd stroma and immunohistochemistry indicated neural and mesenchymal differentiation, and diagnosis was made by molecular detection of the EWS-WT1 fusion gene product. DSRCT should be considered in the differential diagnosis of intracranial small round cell tumors.

Mesenchymal neoplasms of the major salivary glands: clinicopathological features of 18 cases

Non-lymphoid mesenchymal neoplasms of salivary gland origin are rare, accounting for 1.9-5% of major salivary gland tumors. We describe the clinico-pathologic features of 18 cases of mesenchymal neoplasms of the major salivary glands experienced at Asan Medical Center, Seoul, Korea, from 1998 to 2004. Mesenchymal neoplasms accounted for 3.4% of the total of 524 major salivary gland tumors. The parotid gland was the preponderant site (15 cases). Thirteen tumors were benign, constituting 3.5% of the total of 371 benign neoplasms. Schwannomas were the most common benign tumors (six cases), followed by lipomas (three cases), plexiform neurofibroma, hemangioma, desmoid tumor, and solitary fibrous tumor (one each). The malignant tumors consisted of one dermatofibrosarcoma protuberans, synovial sarcoma, leiomyosarcoma, pleomorphic liposarcoma and desmoplastic small round cell tumor each. Immunohistochemical analysis for the expression of vimentin, actin, desmin, neuron-specific enolase, keratin, CD34, CD99 and bcl-2 contributed to the differential diagnoses. Genetic analysis for fusion transcripts was conclusive in the diagnosis of desmoplastic small round cell tumor, which is extremely rare at this location. Pre-operative imaging study and fine needle aspiration cytology had limitations in prediction of the mesenchymal nature of the tumors, due to either low index of suspicion, similarities to mixed tumors, or specimen inadequacy. Awareness of the development of various mesenchymal tumors in the major salivary glands could increase the accuracy of preoperative and postoperative diagnosis, and therapeutic efficacy.

Spindle cell tumor with EWS-WT1 transcript and a favorable clinical course: a variant of DSCT, a variant of leiomyosarcoma, or a new entity? Report of 2 pediatric cases

We report 2 intra-abdominal tumors originally diagnosed as leiomyosarcomas, occurring in adolescents, one as a second malignancy after a Hodgkin lymphoma. Both tumors exhibited unusual morphologic features characterized by spindle cells arranged in sheets or in fascicles, devoid of the typical desmoplastic stroma. Cytokeratins and mesenchymal markers, including smooth muscle actin, desmin, and muscle specific actin, were coexpressed in the tumor cells, whereas EMA was negative. Reverse transcription-polymerase chain reaction analysis showed an EWS-WT1 fusion transcript. Both patients are alive and in complete remission at 3 and 13 years after diagnosis, respectively. These tumors raise a variety of diagnostic possibilities. They could represent intra-abdominal desmoplastic small round cell tumor, with histologic features of epithelioid leiomyosarcoma or an unusual subtype of leiomyosarcoma with an EWS-WT1 transcript. Alternatively, they could represent an unrecognized subgroup of tumors with spindle cell morphology, bearing the same translocation as desmoplastic small round cell tumor, but characterized by a more favorable clinical course.

Cytology of desmoplastic small round-cell tumor: comparison of pre- and post-chemotherapy fine-needle aspiration biopsies

BACKGROUND

Desmoplastic small round-cell tumor (DSRCT) is an aggressive malignancy of young adults, which is amenable to fine-needle aspiration biopsy (FNAB). As this entity is increasingly recognized and biopsied, cytopathologists are compelled to become familiar with the range of cytologic features of DSRCT. In addition, postchemotherapy tumors may be sampled to confirm disease recurrence before planning additional therapy. This study was designed to compare prechemotherapy and postchemotherapy cytomorphology of DSRCT and to evaluate for distinct chemotherapy-induced changes.

METHODS

The authors searched their respective institutional databases for all DSRCT cases with an associated FNAB. FNAB slides, immunocytochemistry, and cytogenetic results were reviewed.

RESULTS

Six aspirates from 5 patients were identified, 3 of which were postchemotherapy. The postchemotherapy cases demonstrated cytologic findings not typically described in DSRCTs, including prominent and conspicuous nucleoli, discohesive single-cell architecture, and slightly larger cell size.

CONCLUSIONS

Cytomorphologic variability was prominent in prechemotherapy cases, and no case could be classified as DSRCT on cytology alone; immunohistochemistry was necessary for definitive diagnosis. Chemotherapy increased the spectrum of cytologic features. The most notable difference between the 2 groups was a predominantly discohesive single-cell pattern with conspicuous nucleoli in the postchemotherapy group, instead of the clustering pattern of medium-sized cells with inconspicuous nucleoli typically attributed to de novo cases reported in the literature.

Desmoplastic small round cell tumors: cytologic, histologic, and immunohistochemical features

Desmoplastic small round cell tumor (DSRCT) is a recently recognized clinicopathologic entity that has a predilection for adolescent males and usually affects the abdominal cavity. Due to its uncommon nature, many pathologists lack experience with this tumor. The literature regarding DSRCT is reviewed with special attention to its histologic and cytologic diagnosis. Morphologic features of DSRCT and its immunohistochemical and cytogenetic profile are summarized and differential diagnosis with other small round cell tumors is discussed. As observed by both histologic and cytologic examinations, small round blue cells and fibrosclerotic stroma are the striking morphologic features of DSRCT. The typical immunohistochemical profile is characterized by coexpression of epithelial, mesenchymal, myogenic, and neural markers. Cytogenetically, this tumor harbors a specific karyotypic abnormality, namely t(11;22)(p13;q12). These features distinguish DSRCT from other members of the family of small round cell tumors.

Intraabdominal desmoplastic small round cell tumors: a diagnostic and therapeutic challenge

BACKGROUND

Intraabdominal desmoplastic small round cell tumors (IDSRCT) are uncommon but aggressive tumors that occur in young males. To the authors' knowledge, only limited data are available on the natural history and optimal treatment of this disease.

METHODS

The authors reviewed 12 patients with IDSRCT who were treated at their institution between January 1991 and December 2001.

RESULTS

All patients were males, with a median age of 26 years. All patients were symptomatic at the time of presentation, with a mean duration of symptoms of 2 months. Common presenting symptoms and signs were abdominal pain (67% of patients), palpable abdominal mass (58% of patients), abdominal distension (42% of patients), and hepatomegaly (33% of patients). Six patients (50%) had distant metastases at presentation. Five patients underwent biopsy only. Surgical resection was attempted in seven patients and included macroscopic total resection in three patients and debulking in four patients. All of those patients subsequently developed recurrent or progressive disease, which required a second operation in six patients. Overall, 6 patients (50%) developed symptomatic intestinal obstruction requiring surgical management, and 3 patients (25%) developed ureteral obstruction. All 12 patients received multiagent chemotherapy. Seven patients (55%) also received radiation therapy. The median survival of patients who underwent surgical resection was 34 months, whereas the median survival of patients who underwent biopsy alone was 14 months. One patient remained alive 72 months after he underwent complete resection of primary and recurrent tumors, and 1 patient remained alive with disease 32 months after he underwent complete resection of a primary tumor.

CONCLUSIONS

Patients with IDSRCT presented with a short duration of nonspecific symptoms, and the disease was fatal almost uniformly, regardless of the treatment modality used. Surgical resection may prolong survival in some patients.

Desmoplastic small round cell tumour: Cytological and immunocytochemical features

Background

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive neoplasm. The cytological diagnosis of these tumors can be difficult because they show morphological features quite similar to other small round blue cells tumors. We described four cases of DSRCT with cytological sampling: one obtained by fine needle aspiration biopsy (FNAB) and three from serous effusions. The corresponding immunocytochemical panel was also reviewed.

Methods

Papanicolaou stained samples from FNAB and effusions were morphologically described. Immunoreaction with WT1 antibody was performed in all cytological samples. An immunohistochemical panel including the following antibodies was performed in the corresponding biopsies: 34BE12, AE1/AE3, Chromogranin A, CK20, CK7, CK8, Desmin, EMA, NSE, Vimentin and WT1.

Results

The smears showed high cellularity with minor size alteration. Nuclei were round to oval, some of them with inconspicuous nucleoli. Tumor cells are clustered, showing rosette-like feature. Tumor cells in effusions and FNA were positive to WT1 in 3 of 4 cytology specimens (2 out 3 effusions and one FNA). Immunohistochemical reactions for vimentin, NSE, AE1/AE3 and WT1 were positive in all cases in tissue sections.

Conclusion

The use of an adjunct immunocytochemical panel coupled with the cytomorphological characteristics allows the diagnosis of DSRCT in cytological specimens.

Primary desmoplastic small round cell tumor of bone: report of a case with cytogenetic confirmation

We report a case of desmoplastic small round cell tumor occurring in the right ilium of a 13-year-old boy. Morphologically, the neoplasm consisted of small round cells of primitive appearance with a diffuse growth pattern replacing marrow space and eroding bone. Immunohistochemical staining was positive for vimentin, synapsin, CD99 (MIC2 protein), and FLI-1, prompting an initial diagnosis of Ewing sarcoma/primitive neuroectodermal tumor. However, a diagnosis of desmoplastic small round cell tumor was rendered after the detection by cytogenetic analysis of the reciprocal chromosomal translocation, t(11;22)(p13;q12), which is uniquely associated with this tumor. This is the first documented instance of desmoplastic small round cell tumor arising in bone.

Pediatric-type sarcomas in adult patients

Sarcomas included in the broad group of small round-cell tumors (SRCT) and some non-SRCT lesions that typically are seen in pediatric-age patients can rarely occur in adults. However, there are differences in the anatomic sites that are involved and the prognosis in these two patient groups. The diagnosis of pediatric-type sarcomas in adults is often challenging because of the unusual contextual clinical setting and morphologic features. Immunohistochemical studies have greatly facilitated this process. Moreover, limited biomolecular studies that have been conducted have demonstrated comparable cytogenetic alterations in adults and children with pediatric-type tumors. They also have raised interesting questions concerning possible biological bases for differences in clinical behavior in the two cohorts. This review focuses on the morphological, immunohistochemical, and molecular characteristics of childhood-type sarcomas that affect adults, with emphasis on possible pitfalls in differential diagnosis.

Intra-Abdominal Desmoplastic Small Round Cell Tumor with Elevated Serum CA 125: A Case Report

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive tumor usually involving the peritoneum. It occurs more commonly in young males and is characterized by distinctive clinical, histologic, and immunophenotypic features. The histogenesis of DSRCT remains unknown. Coexpression of epithelial, mesenchymal, and neural antigens in the same cell provides evidence that DSRCT may arise from a primitive pluripotent stem cell with divergent differentiation. Recently, according to cytogenetic studies, some authors have proposed that the divergent differentiation of DSRCT may be the result of the fusion of Ewing's sarcoma gene and Wilms' tumor suppressor gene. Clinically, an elevated serum CA 125 concentration is found in some patients with DSRCT. We present the case of a 29-year-old man with diffuse intra-abdominal DSRCT and elevated serum CA 125 concentration and briefly review the relevant literature.

Immunophenotype of desmoplastic small round cell tumors as detected in cases with EWS-WT1 gene fusion product

Desmoplastic small round cell tumor is a rare tumor typically involving peritoneum. Although the histogenesis of desmoplastic small round cell tumor has yet to be elucidated, immunophenotypical and morphological analysis shows a characteristic divergent phenotype overlapping with other round cell tumors such as Ewing's sarcoma/primitive neuroectodermal tumor, rhabdomyosarcoma, small cell mesothelioma, and carcinoma. Detection of the EWS-WT1 gene fusion is characteristic of desmoplastic small round cell tumor and has been used reliably in tumor diagnosis. In this study, we evaluated the immunophenotype of 23 desmoplastic small round cell tumor cases with the EWS-WT1 gene fusion product identified by reverse transcription-polymerase chain reaction. Paraffin sections were stained with antibodies against calretinin, WT1 (C19), desmin, myoglobin, MyoD, Myf5, myogenin, placental alkaline phosphatase, cytokeratins, MIC2, HER2/neu and c-kit using standard immunohistochemical methods. Immunoreactivity was evaluated semiquantitively by light microscopy. Desmoplastic small round cell tumors showed reactivity with calretinin in 4/21, desmin in 21/23, myoglobin in 5/17, placental alkaline phosphatase in 17/21, HER2/neu in 7/18 (3+ in 1 and 1+ in 6), c-kit in 2/14, MIC2 in 13/23, WT1 in 16/23, CAM5.2 in 21/23, and AE1/3 in 16/23 cases. The most sensitive myogenic and epithelial markers are desmin and CAM 5.2. Although nuclear reactivity of the early myogenic regulatory factors (MyoD, myogenin, Myf5) was not detected, myoglobin immunoreactivity was present in 29% of desmoplastic small round cell tumors. HER2/neu overexpression (3+) and c-kit expression are uncommon in desmoplastic small round cell tumors. A panel of myogenic and epithelial markers should be used to detect the divergent phenotype in desmoplastic small round cell tumors, a key feature in the differential diagnosis. Detection of EWS-WT1 fusion becomes critical for the diagnosis when the characteristic divergent phenotype cannot be detected immunohistochemically.

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.

Desmoplastic small round cell tumor: imaging findings associated with clinicopathologic features

PURPOSE

To describe imaging findings of desmoplastic small round cell tumor (DSCRT) and to clarify the relation between radiologic appearances and clinicopathologic features.

MATERIALS AND METHODS

CT scans and MRI examinations of four male patients with histologically confirmed DSCRT (mean age = 20 years) were retrospectively analyzed.

RESULTS

The common imaging finding was multiple peritoneal masses with regular contour situated within mesentery. Tumors showed central low attenuation in 75% of patients on nonenhanced CT. All tumors showed inhomogeneous enhancement on CT. Small foci of punctate calcification were identified in a part of the tumor in all patients. Bone metastases were identified on enhanced CT in two patients 2 and 8 months after diagnosis, respectively. Pleural dissemination was identified in all patients, and one patient had double-sided dissemination. T2-weighted MRI showed inhomogeneous high signal intensity, and small cysts were identified in two patients. Fluid-fluid levels were identified in six tumors on T2-weighted images, which suggested the presence of hemorrhage. Tumors had inhomogeneous signal intensity low or isointense relative to skeletal muscle on T1-weighted images. Two lesions exhibited inhomogeneous enhancement with central low intensity consistent with necrosis.

CONCLUSION

Imaging studies can depict disseminated characteristics and disease extent during the clinical course of DSRCT.

Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical, and molecular study of 32 tumors

Desmoplastic small round cell tumor is a rare, aggressive neoplasm that mainly affects young male patients and is characterized by a reciprocal translocation t(11;22)(p13;q12) associated with the EWS-WT1 gene fusion transcript. Clinical, histopathologic, immunohistochemical, and molecular genetics features were reviewed for 32 tumors. There were 29 male and three female patients, with ages from 6 to 54 years (mean, 25 years). The main clinical signs and symptoms included abdominal pain (eight patients), weight loss (five patients), and presence of umbilical hernia (four patients). Two tumors primarily involved the ethmoid sinus and the soft tissues of the scalp; the other tumors (mean size, 10 cm) involved the abdominal cavity (88%). One patient presented initially with an axillary lymph node metastasis. Generally, all tumors showed the typical histologic findings of variably sized clusters of small, round, or spindled cells lying in a desmoplastic stroma. The neoplastic cells in formalin-fixed, paraffin-embedded tissue sections were positive for desmin (dot pattern) (81% of the cases), WT1 (91%), keratin (87%), neuron-specific enolase (84%), CD99 (23%), and actin (3%). The EWS-WT1 gene fusion transcript was detected in 29 of 30 tumors. One tumor with typical clinicopathologic and immunohistochemical features did not show the gene fusion. Follow-up for 27 patients showed that 19 patients (70%) died of uncontrolled, local, or widespread metastatic disease 3-46 months (mean, 20 months) after diagnosis, and eight patients were alive with known evidence of disease. Occasionally, desmoplastic small round cell tumor lacks the classic clinical, histologic, and immunohistochemical features. This study emphasizes the utility of analysis of the EWS-WT1 gene fusion transcript, which was performed on paraffin-embedded tissues, to confirm the diagnosis.

Sinonasal desmoplastic small round cell tumor: a case report

A case of sinonasal desmoplastic small round cell tumor in a 21-year-old woman is presented. The tumor possessed the diagnostic histologic, immunohistochemical, and genetic characteristics of desmoplastic small round cell tumor. Histologically, the tumor was composed of nests of tumor cells surrounded by a desmoplastic stroma. Immunohistochemical staining was positive for keratin, vimentin, desmin, and, focally, neuron-specific enolase. The desmin immunopositivity was of a classic dot-like perinuclear pattern. RT-PCR analysis showed the fusion transcript resulting from the t(11;22)(p13;q12) reciprocal translocation. This case of sinonasal desmoplastic small round cell tumor, the third reported case not associated with a serosal surface, further obscures the nature and histogenesis of this entity.

Ewing tumor: tumor biology and clinical applications

The Ewing tumor family includes classical Ewing's sarcoma of bone and soft tissues, peripheral primitive neuroectodermal tumors (pPNET), Askin tumor, and other less frequent variants. This group of tumors is defined by the consistent presence of chromosomal translocations resulting in gene fusions between EWS gene and a member of the ETS family of transcription factors, mainly FLI1 and ERG. Analogous fusions are seen in other solid developmental tumors, like desmoplastic small round cell tumor. These fusions, which are consistently present and tumor-specific, control transcription of several target genes, largely unknown but critical to cell proliferation and differentiation. Therefore, gene fusions are useful to diagnose and classify small round cell tumors, have prognostic significance, are probably useful to detect micrometastasis and monitor minimal residual disease, and are potential therapeutic targets. Secondary molecular alterations, which include mutations of cell cycle regulatory genes, are not tumor-specific but are related to progression and may have prognostic value. The Ewing tumor family represents a paradigm of the application of the knowledge of biology of neoplasia to the clinical management of patients.

Successful dose-intensive treatment of desmoplastic small round cell tumor in three children

Desmoplastic small round cell tumor (DSRCT) is a rare soft tissue tumor of primitive origin occurring primarily in children and young adults. Based on published reports in the literature, the response to conventional chemotherapy is poor. We report three pediatric patients successfully treated with dose-intensive, multimodal therapy. Between August 1994 and March 1998, we evaluated three consecutive patients with DSRCT at Children's Hospital and Regional Medical Center, Seattle, Washington. We established the diagnosis based on clinical presentation, radiologic staging, and pathologic review with immunohistochemical staining. All patients received a combined modality protocol including dose-intensive chemotherapy (two of them with peripheral blood stem cell [PBSC] support), second look surgery, and consolidative local irradiation. The patients remain in continuous remission at 66, 42, and 26 months after diagnosis, respectively. Two of our patients were younger than any previously reported patient, extending the age group for which DSRCT should be considered on diagnosis of small round cell tumors. The uniform survival achieved in our series indicates potential benefit for the combination of dose-intensive multiagent chemotherapy, local irradiation, and aggressive surgical approach in this disease.

Contribution of molecular genetic data to the classification of sarcomas

Many sarcomas are characterized by specific recurrent chromosomal translocations which provide powerful diagnostic tumor markers. Since 1992, the genes involved by almost all of these translocations have been cloned, inaugurating a new era in the study of sarcomas. At the biological level, these chromosomal translocations produce highly specific gene fusions, usually encoding aberrant chimeric transcription factors. Clinically, the correlation of these translocation-derived genetic markers and discrete histopathologic entities has been remarkable. Fusion gene detection has confirmed and refined the nosology of several sarcoma groups. The overall effect has been to strengthen certain pathological concepts rather than to revolutionize. The focus of this brief review is the recent impact that the cytogenetic and molecular detection of these translocations has had on sarcoma diagnosis and classification.