Desmoplastic small round cell tumor

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Desmoplastic small round cell tumour; Desmoplastic small round blue cell tumor; Desmoplastic small round blue cell tumour; Intraabdominal desmoplastic small round blue cell tumor; Desmoplastic small cell tumor; Desmoplastic cancer; Desmoplastic sarcoma; DSRCT

Overview

Desmoplastic small round cell tumor is a rare but highly fatal malignancy.

Historical Perspective

Desmoplastic small round cell tumor was first described by pathologists, William L. Gerald and Juan Rosai, in 1989.

Pathophysiology

Pathogenesis

Desmoplastic small round cell tumor is a highly aggressive, rare tumor of mesenchymal origin whose oncogenic effect is presumed to originate from the unique chromosomal translocation t(11;22)(p13:q12), leading to the fusion of the N-terminal domain of Ewing’s sarcoma gene EWS, to the C-terminal domain of Wilms’ tumor suppressor gene, WT1, which is found in most but not all desmoplastic small round cell tumors.

Genetics

Desmoplastic small round cell tumor is associated with a unique chromosomal translocation t(11;22)(p13:q12), resulting in an EWS/WT1 transcript that is diagnostic of this tumor. This transcript codes for a protein that acts as a transcriptional activator that fails to suppress tumor growth. The EWS/WT1 translocation product targets ENT4. ENT4 is also known as PMAT.

Associated Conditions

There may be a chimeric relationship between desmoplastic small round cell tumor, and Wilms' tumor and Ewing's sarcoma. Together with neuroblastoma and non-Hodgkin's lymphoma, they form the small cell tumors.

Gross Pathology

Desmoplastic small round cell tumor tends to grow along a serosal lining, most commonly the peritoneal surface, but other primary sites have been described.

Gallery

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  _{Micrograph of a desmoplastic small round cell tumor, showing the characteristic desmoplastic stroma and angulated nests of small round cells on H&E stain.}

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  _{Display of small round blue cells characteristic of desmoplastic small-round-cell tumor.}

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  _{Cell exhibiting blue oval and round shapes of desmoplastic small round blue cell tumor.}

Differentiating Desmoplastic Small Round Cell Tumor from other Diseases

• Desmoplastic small round cell tumor in the abdomen may cause gastrointestinal symptoms and mimic other abdominal tumors. So, they must be differentiated from other tumors in the abdomen, such as:

• Rhabdomyosarcoma
• Neuroblastoma
• Mesenteric carcinoid

• In older patients, desmoplastic small round cell tumor must be differentiated from:

• Non-Hodgkins lymphoma
• Peritoneal mesothelioma
• Peritoneal carcinomatosis

• In males, desmoplastic small round cell tumor may be mistaken for testicular germ cell tumor while in females, desmoplastic small round cell tumor may be mistaken for ovarian cancer.
• Desmoplastic small round cell tumor must be differentiated from other small-round blue cell cancers, such as:

• Ewing sarcoma
• Neuroblastoma
• Embryonal rhabdomyosarcoma
• Pineoblastoma
• Wilms tumor
• Retinoblastoma
• Hepatoblastoma
• CNS primitive neuroectodermal tumor (CNS-PNET)
• Peripheral primitive neuroectodermal tumor (pPNET)
• Askin tumor
• Neuroepithelioma
• Acute leukemia
• Small cell mesothelioma

Epidemiology and Demographics

Incidence

• Age-adjusted incidence rate of desmoplastic small round cell tumor for African Americans and Caucasians is 0.05 and 0.02 per 100,000 individuals, respectively.
• The overall age-adjusted incidence rate of desmoplastic small round cell tumor is 0.03 per 100,000 individuals, with a peak incidence of 0.074 per 100,000 individuals in the 20–24 years of age group.

Age

Peak age of incidence for desmoplastic small round cell tumor is between 20 and 24 years.

Gender

Males are more commonly affected with desmoplastic small round cell tumor than females. The male to female ratio is approximately 4 to 1.

Race

Desmoplatic small round cell tumor usually affects individuals of the African American and Caucasian race. Latin American and Asian individuals are less likely to develop desmoplatic small round cell tumor.

Gallery

_{(a) Overall age-adjusted incidence of desmoplastic small round cell tumor, (b) Sex-based age-adjusted incidence of desmoplastic small round cell tumor. Males are more likely than females to get desmoplastic small round cell tumor, (c) Race-based, age-adjusted incidence of DSRCT. African Americans are more likely than Caucasians to get desmoplastic small round cell tumor.}

Demographics

_{Adapted from Christina K. Lettieri et al.}

Risk Factors

There are no established risk factors for desmoplastic small round cell tumor.

Natural History, Complications, and Prognosis

Complications

Complication sof desmoplastic small round cell tumor include:

• Peritoneal seeding
• Lymph nodal involvement
• Metastasis (liver, bone, lung)

Prognosis

Gallery

_{(a) Race-based survival of desmoplastic small round cell tumor. There may be a survival disadvantage for African americans compared to Caucasians. Although it did not reach statistical significance, this analysis suggests that African americans are 33% more likely to succumb to desmoplastic small round cell tumor than are Caucasians, (b) Treatment-based survival of desmoplastic small round cell tumor, radiation versus no radiation. There was no statistically significant difference in survival amongst patients who received radiation therapy compared to those who did not, (c) Treatment-based survival of demsoplastic small round cell tumor, radiation after surgery versus no radiation. Patients who received radiation following surgery fared better than those patients who did not.
Adapted from Christina K. Lettieri et al.}

Diagnosis

Symptoms

• There are few early warning signs that a patient has a desmoplastic small round cell tumor.
• Patients are often young and healthy as the tumors grow and spread uninhibited within the abdominal cavity. These are rare tumors and the symptoms are often misdiagnosed by physicians. The abdominal lump may grow to enormous size before being noticed by the patient.

Common Symptoms

Common symptoms of desmoplastic small round cell tumor include:

• Abdominal distention
• Lump in abdomen
• Abdominal pain
• Back pain
• Gastrointestinal obstruction
• Lack of appetite
• Fatigue
• Weakness
• Cachexia

Less Common Symptoms

Less common symptoms of desmoplastic small round cell tumor include:

• Unknown lumps
• Thyroid conditions
• Hormonal problems
• Blood clotting problems
• Kidney or urological problems
• Lump in the testicle, breast, uterus, vagina, or ovary

CT

• Abdominal CT scan may be diagnostic of desmoplastic small round cell tumor.
• Findings on CT scan suggestive of desmoplastic small round cell tumor include a solitary to multiple soft tissue masses with no definite organ of origin, usually in the retrovesical or rectouterine space, which enhance heterogenously on contrast studies. Necrosis, hemorrhage, and fibrous components are common.
• Peritoneal seeding, lymph nodal involvement, liver and bone metastases may also be demonstrated.