Desmoplastic small round-cell tumor
Description, Causes and Risk Factors:
DSRCT is a rare and aggressive tumour that affects young males. It is usually an abdominopelvic malignancy that demonstrates distinct histological appearances and a unique cytogenetic pro?le.
Research has indicated that there is 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 or B cell tumors.
The disease is known to pop up from primitive cells during childhood. Chromosomal translocations chromosome 11 and chromosome 22 causes this disease. In DSRCT, the chromosomes have become rearranged so that instead of having a pair of chromosomes 11 and pair of chromosome 22, there has been an incorrect repair of some random chromosome damage, so that part of chromosome 11 is "stuck onto" part of chromosome 22. As a result of this incorrect repair, the EWS gene which normally lives on chromosome 22 finds itself next to the WT1 gene, which normally lives on chromosome 11 - this process is called a chromosomal translocation.
DSRCTs have a tendency for peritoneal and omental spread, lymph node involvement and hematogenous metastasis, especially to the liver. Primary DSRCTs have been described originating outside the abdominal cavity — arising from the other mesothelial surfaces such as lung pleura and tunica vaginalis. Desmoplastic small round-cell tumor can also arise from solid organs such as the ovaries, liver, kidneys, pancreas, bone and even the posterior cranial fossa.
Clinical signs and symptoms of Desmoplastic small round-cell tumor are nonspeci?ac.DSRCT typically arises from abdominal or pelvic peritoneumas a diffuse mass, which tends to be large at presentation— up to 40 cm in some cases. It is associated withabdominal distension and pain, ascites and hepatomegaly.Pressure effects of the tumour on the nearby structureshave also been described, such as intestinal obstruction,hydronephrosis and urinary/erectile dysfunction.
The symptoms that usually appear may include:
- Abdominal pain.
- Back pain.
- Abdominal distention.
- Gastrointestinal obstruction.
- Loss of appetite.
The key features of Desmoplastic small round-cell tumor may include:
Histology: Macroscopic appearances are of a bosselatedouter surface, cut surfaces are grey with areas of necrosiswithin.Microscopically, the tumour usually forms nests or strandsof small round cells embedded in desmoplastic stroma. The ratio of tumour cells to stroma variessigni?cantly across a biopsy specimen. Tumour cells tendto be small to medium in size with scanty cytoplasm,round to oval nuclei and visible mitotic.
Cytology: Analysis is possible from tissue biopsy and FNAspecimens, as well as ascitic and pleural tap ?uid.This is especially useful when biopsy of the tumour bulk is difficult.
Immunohistochemistry: Desmoplastic small round-cell tumor cells are immunoreactiveto epithelial, mesenchymal, myogenic and neural markers. They demonstrate positive staining for vimentin,desmin, smooth muscle actin, neuron-speci?cenolase, epithelial membrane antigens and cytokeratins. This polyphenotypic antigen expression pro?le isunique among small round blue cell tumours.
Cytogenetics: The EWS-WT1 gene fusion has morerecently been discovered to be disease-speci?c to DSRCT. This characteristic reciprocal translocation isdemonstrated by ?uorescence in situ hybridisation (FISH)or reverse transcriptase-polymerase chain reaction technique, and is speci?c to Desmoplastic small round-cell tumor at any primary location. It is the de?nitive diagnostic marker.
Desmoplastic small round cell tumor remains a vexing disease with little long-term survival. Current treatment prolongs life and rarely achieves cure. Some of the treatments that are available for Desmoplastic small round-cell tumor include:
- Radiation therapy.
- Radiofrequency ablation.
- Hematopoietic stem cell transplantation.
- Intraperitoneal hyperthermic chemoperfusion (IPHC).
At the present time, the treatment of DSRCT relies heavily on chemotherapy or drug treatment. As the tumour has often spread widely at the time of diagnosis, treatments such as surgery or radiotherapy are much less likely to be useful.
Further advances in treatment of Desmoplastic small round-cell tumor involve the development of new therapies that specifically target the cellular regulatory mechanism of DSRCT. The fusion protein created by the characteristic chromosomal translocation t(11;22)(p13;q12), has been shown to induce production of endogenous platelet-derived growth factor (PDGF), T-cell acute lymphoblastic leukemia-associated antigen 1 protein (TALLA-1), and interleukin-2/15 receptor. Each of these is important in tumorigenesis.
Platelet-derived growth factor is a chemoattractant that is thought to enhance recruitment and proliferation of fibroblast and endothelial cells. This may explain the dense stroma and fibrosis associated with Desmoplastic small round-cell tumor.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.