Positron emission tomography for response assessment in desmoplastic small round cell tumor

Role and Efficacy of 18F-FDG PET/CT in Following Up Desmoplastic Small Round Cell Tumor of the Abdomen: A Case Report

Desmoplastic small round cell tumor (DSRCT) is an exceptionally rare and highly aggressive primary peritoneal neoplasm predominantly seen in adolescents and young adults. Despite the availability of various treatment modalities, the prognosis remains grim due to the tumor's aggressive nature and tendency for widespread metastasis. Although imaging of DSRCT is frequently documented using computed tomography (CT), the role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the initial diagnosis, staging, and particularly in the follow-up evaluation, is less explored. This case report details the role and efficacy of 18F-FDG PET/CT in the follow-up of a patient with extensive peritoneal involvement by DSRCT, demonstrating its added advantage in monitoring treatment response over conventional CT imaging.

Metastatic Pulmonary Desmoplastic Small Round Cell Tumor on FDG PET/CT

ABSTRACT

A 33-year-old woman presents with cough and hemoptysis for 1 month. Chest CT showed a soft tissue mass in the left upper lobe of the lung. FDG PET/CT showed multiple foci of intense activity not only in the lung but also in the lymph nodes and the bones, which was diagnosed as lung malignancy with metastases. Histopathology revealed desmoplastic small round cell tumor. Our case indicated that, although the incidence is low, desmoplastic small round cell tumor should be considered among differential diagnoses of lung malignancies.

Imaging of pediatric abdominal soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

This paper provides imaging recommendations for pediatric abdominal tumors that arise outside of the solid viscera. These tumors are rare in children and have been categorized in two groups: abdominal wall and peritoneal tumors (desmoid tumor and desmoplastic small round cell tumor) and tumors that arise from the gastrointestinal tract (gastrointestinal stromal tumor and gastrointestinal neuroendocrine tumor). Authors offer consensus recommendations for imaging assessment of these tumors at diagnosis, during follow-up, and when off-therapy.

Intra-Abdominal Desmoplastic Small Round Cell Tumor (DSRCT) and the Role of Hyperthermic Intraperitoneal Chemotherapy (HIPEC): A Review

Desmoplastic small round cell tumor is a very rare and highly aggressive soft tissue sarcoma, usually presenting with multiple intra-abdominal tumors in young males. Patients present with advanced disease and the overall survival is dismal. Multiple studies report relatively favorable outcomes with multimodal treatment consisting of chemotherapy, surgery and radiotherapy. If resection is feasible, complete cytoreductive surgery is the cornerstone of surgical treatment. The benefit of hyperthermic intraperitoneal chemotherapy in addition to cytoreductive surgery is unclear, and few studies have evaluated this option. We sought to identify the role of hyperthermic intraperitoneal chemotherapy in patients with intra-abdominal desmoplastic small round cell tumor. Our review of the available literature revealed no clear survival benefit in performing hyperthermic intraperitoneal chemotherapy after cytoreductive surgery.

Advances in the treatment of pediatric solid tumors: A 50-year perspective

In the United States, more than 10 000 cancers occur annually in children aged 0-14 years, and more than 5000 in adolescents aged 15-19. In the last 50 years, significant advances have been made in imaging, molecular pathology, stage and risk assessment, surgical approach, multidisciplinary treatment, and survival for pediatric solid tumors (particularly neuroblastoma, Wilms tumor, rhabdomyosarcoma, and hepatoblastoma). Moreover, the molecular driver for fibrolamellar hepatocellular carcinoma, which occurs in adolescence and young adulthood, has been identified.

Intra-Abdominal Desmoplastic Small Round Cell Tumor: Current Treatment Options and Perspectives

Intra-abdominal desmoplastic small round cell tumor (IDSRCT) is a rare and highly malignant soft tissue neoplasm, which is characterized by rapid progression and poor prognosis. The mechanism underlying the development of this neoplasm remains elusive, but all cases are characterized by the chromosomal translocation t (11;22) (p13; q12), which results in a formation of EWSR1-WT1 gene fusion. The diagnosis of IDSRCT is often made with core-needle tissue biopsy specimens or laparoscopy or laparotomy. Immunohistochemical analyses have shown the co-expression of epithelial, neuronal, myogenic, and mesenchymal differentiation markers. FISH or reverse transcription polymerase chain reaction detecting EWS-WT1 fusion can be performed to assist in molecular confirmation. There is no standard of care for patients with IDSRCT currently, and majority of newly diagnosed patients received the aggressive therapy, which includes >90% resection of surgical debulking, high-dose alkylator-based chemotherapy, and radiotherapy. More recently, targeted therapy has been increasingly administered to recurrent IDSRCT patients and has been associated with improved survival in clinical conditions. Immunotherapy as a possible therapeutic strategy is being explored in patients with IDSRCT. In this review, we summarize currently available knowledge regarding the epidemiology, potential mechanisms, clinical manifestations, diagnosis, treatment, and prognosis of IDSRCT to assist oncologists in comprehensively recognizing and accurately treating this malignancy.

Desmoplastic Small Round Cell Tumors: A review with focus on clinical management and therapeutic options

Desmoplastic Small Round Cell Tumors (DSRCTs) are an entity of rare, aggressive soft tissue sarcomas described by Gerald and Rosai in 1989. It predominantly affects male adolescents and young adults, with a peak incidence between an age of 20 and 30 years. Typically, DSRCT demonstrate as multiple small tumor nodules within the abdominal cave, retroperitoneum and pelvis. In more than 50% of the cases, the neoplasm presents metastatic at the timepoint of diagnosis. Histologically, DSRCTs have a characteristic morphology with sharply demarcated islands of uniform small round cells in abundant desmoplastic stroma organized in loose extracellular matrix. Immunohistochemistry reveals a polyphenotypic differentiation with co-expression of epithelial, myogenic, mesenchymal and neural markers. The morphology is highly variable and can hinder diagnosis. The most consistent molecular characteristic of DSRCT is the reciprocal t(11;22)(p13q12) translocation. This mutation leads to a formation of the EWSR1-WT1 fusion oncogene, which encodes for a chimeric protein with transcriptional regulatory activity and is regarded as driving source of the disease. To date, there is no standardized concept for clinical management, staging and treatment. Patients receive an aggressive multimodal therapeutic approach consisting of chemotherapy, radical surgical procedures, hyperthermic, intraperitoneal chemotherapy (HIPEC) and radiation. New targeted therapies are used in experimental settings as salvage therapy. So far, none of these therapies showed significant long-term success. This review gives an overview of diagnostic difficulties and pitfalls, discusses therapeutic strategies and highlights options for clinical management.

Comparison of the morphologic criteria (RECIST) and metabolic criteria (EORTC and PERCIST) in tumor response assessments: a pooled analysis

BACKGROUND/AIMS

The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) or European Organization for Research and Treatment of Cancer (EORTC) criteria are used to assess metabolic tumor responses. However, tumor responses have shown considerable discrepancies between the morphologic criteria (Response Evaluation Criteria in Solid Tumors [RECIST]) and metabolic criteria. We performed this pooled study to compare the RECIST and metabolic criteria in the assessment of tumor responses.

METHODS

Electronic databases were searched for eligible articles with the terms "RECIST," "PERCIST," or "EORTC criteria." The level of concordance in the tumor responses between the two criteria was estimated using κ statistics.

RESULTS

A total of 216 patients were collected from eight studies comparing the RECIST and EORTC criteria. The agreement of tumor responses between the two criteria was moderate (κ = 0.447). Eighty-six patients (39.8%) showed disagreement: tumor response was upgraded in 70 patients and downgraded in 16 when adopting the EORTC criteria. The EORTC criteria significantly increased the overall response rate (53% vs. 28%, p < 0.0001). The agreement of tumor responses between the RECIST and PERCIST was deemed fair (κ = 0.389). Of 407 patients from nine studies, 181 (44.5%) showed a discrepancy: using the PERCIST, tumor response were upgraded in 151 patients and downgraded in 30. When adopting the PERCIST, the overall response rate was also significantly increased from 30% to 55% (p < 0.0001).

CONCLUSION

This pooled analysis demonstrates that the concordance of tumor responses between the morphologic criteria and metabolic criteria is not excellent. When adopting the metabolic criteria instead of the RECIST, overall response rates were significantly increased.

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.

Comparison of the RECIST and EORTC PET criteria in the tumor response assessment: a pooled analysis and review

PURPOSE

The EORTC PET criteria (EORTC criteria) are used to assess metabolic tumor response in patients with solid tumors. We conducted this pooled study to compare tumor responses according to the RECIST and EORTC criteria.

METHODS

Electronic databases were searched for eligible articles with the terms of "RECIST" or "EORTC criteria". We found seven articles with the data on the comparison of tumor responses by the RECIST and EORTC criteria.

RESULTS

A total of 181 patients were recruited from the seven studies. Ninety-two patients (50.8%) received cytotoxic chemotherapy and 89 were treated with targeted agents. The agreement of tumor responses between the RECIST and EORTC criteria was moderate (k = 0.493). Of 181 patients, 66 (36.5%) showed disagreement in the tumor responses: tumor response was upgraded in 54 patients and downgraded in 12 when adopting the EORTC criteria. The estimated overall response rates were significantly different between the two criteria (52.5% by the EORTC vs. 29.8% by the RECIST, P < 0.0001). When comparing the two criteria according to the anti-cancer treatments (chemotherapy or targeted therapy), the levels of agreement in tumor responses were not excellent (k = 0.461 for chemotherapy and k = 0.524 for targeted therapy, respectively) regardless of therapeutic types.

CONCLUSION

This pooled study indicates that the concordance of tumor responses between the RECIST and EORTC criteria is not excellent. When adopting the EORTC criteria instead of the RECIST, the overall response rate was significantly increased.

Intra-abdominal desmoplastic small round cell tumors: CT and FDG-PET/CT findings with histopathological association

Desmoplastic small round cell tumors (DSRCTs) are rare and aggressive malignant tumors. The aim of the present study was to analyze computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG-PET)/CT imaging features of intra-abdominal desmoplastic DSRCT, and investigate the association of these features with histopathological results. The present study was a retrospective investigation of 4 patients with DSRCT. All patients underwent CT and dynamic CT, and 1 additionally underwent FDG-PET/CT scanning. Following a tumor resection, routine hematoxylin and eosin staining, and immunostaining, were performed and evaluated. Multiple large abdominopelvic masses were identified in all 4 patients; however, no indications of their site of origin were demonstrated. CT revealed soft-tissue masses with patchy foci of hypodense lesions. Contrast-enhanced CT revealed slightly or moderately heterogeneous enhancement of the lesions. Other observations from these patients included calcification (n=2), peritoneal seeding (n=3), hepatic metastasis (n=3), retroperitoneal lymphadenopathy (n=3) and ascites (n=2). FDG-PET/CT revealed multiple nodular increased FDG uptake in the abdominopelvic masses, and in the liver and peritoneum in 1 case. Intra-abdominal DSRCT demonstrated significant diagnostic characteristics on plain and contrast-enhanced CT. Multiple, bulky soft-tissue masses inside the peritoneal cavity, particularly in male adolescents and young adults, should be considered as potential cases of DSRCT. FDG-PET/CT techniques may be utilized to aid the staging of tumors.

Desmoplastic small round cell tumor 20 years after its discovery

Desmoplastic small round cell tumor (DSRCT) was proposed as a distinct disease entity by William L Gerald and Juan Rosai in 1991. Over 850 patients have been reported in the medical literature. A specific translocation, t(11;22)(p13;q12), is seen in almost all cases, juxtaposing the EWS gene to the WT1 tumor suppressor gene. DSRCT is composed of nests of small round cells with polyphenotypic differentiation, typically a mixture of epithelial, mesenchymal and neural features, surrounded by a prominent desmoplastic stroma. DSRCT has a predilection for adolescent and young adult males, and primarily involves the abdominal cavity and pelvis. Survival is low despite their initial response to multimodal treatment. Most patients relapse with disseminated disease that is unresponsive to further therapy.

Desmoplastic small round cell tumour: the radiological, pathological and clinical features

OBJECTIVES

Desmoplastic small round cell tumours (DSRCTs) are rare aggressive tumours of young adults that present late and have poor prognosis. This review discusses distinctive radiological features, histopathology and clinical course of this soft-tissue sarcoma.

METHODS

From 1991 to 2012, the radiology of 20 patients with pathologically proven DSRCT was independently reviewed by two experienced radiologists. The clinical presentation, treatment and outcome were recorded.

RESULTS

PATIENTS

16 men, four women; mean age 28.3 years. Computed tomography (CT) demonstrated peritoneal/omental masses without an organ of origin (94 %), with the majority of cases demonstrating large (>5 cm) dominant soft-tissue deposit (80 %) with multiple smaller foci. CT and magnetic resonance imaging (MRI) typically demonstrated heterogeneous soft-tissue enhancement with cystic degeneration. A minority (20 %) demonstrated calcification. Lymph node enlargement occurred in 50 % of cases. Distant metastatic disease occurred in 25 %. Painful abdominal masses were clinically predominant. Treatment strategies include combination chemotherapy with debulking surgery and/or radiotherapy. Median survival from diagnosis was 22.8 months.

CONCLUSION

Features of multifocal peritoneal/omental masses, usually in combination with a dominant soft tissue deposit, are distinctive in this rare sarcoma. CT/MRI defines the extent of disease and characterises supporting imaging findings. Prolific desmoplastic reaction histologically separates DSRCT from similar subtypes. Combination treatment strategies can infer a survival benefit but prognosis remains poor. TEACHING POINTS : • DSRCTs are rare tumours of young adults (mean age 28.3 years) with a male predominance (4:1). • Painful abdominal masses clinically predominate. Non-specific features of malignancy can be present. • Multifocal peritoneal masses with a dominant soft tissue lesion is a distinctive imaging finding. • A large desmoplastic reaction differentiates DSRCTs from histologically similar round cell subtypes. • Despite debulking surgery with adjuvant chemotherapy, median survival from diagnosis is 22.3 months.