Desmoid tumor laboratory tests

Immunohistochemical staining of spindle cells of desmoid tumors are positive for nuclear beta-catenin, vimentin, alpha smooth muscle actin, muscle actin and negative for desmin, cytokeratins, and S-100. Antibodies like smooth muscle actin, desmin and KIT may be helpful in distinguishing desmoid tumors from other tumors. In addition, APC germline mutations may be performed in patients with sporadic desmoid tumors with no clinical or famililal signs of FAP but having a family history of colorectal carcinoma in at least one family member.

• Molecular testing can be performed in general by performing a variety of following methods:
  • In situ hybridization technique, such as fluorescence in situ hybridization (FISH)
  • Immunohistochemistry (IHC)
  • Next-generation sequencing (NGS)
  • Polymerase chain reaction (PCR)
  • Comparative genomic hybridization (CGH)
  • Karyotyping including spectral karyotyping
  • mRNA analysis
  • Tissue microarrays (TMAs)
  • Southern blot test
  • Northern blot test
  • Western blot test
  • Eastern blot test

• Molecular testing for desmoid tumor is done in order to:
  • Assist (and in some cases, confirm) the initial diagnosis of desmoid tumor
  • Distinguish other tumors/conditions that have similar histological features, when examined by a pathologist under the microscope
  • Help in determining treatment options
  • Confirm recurrence of the tumor: Tumor recurrence can either be at the original tumor site, or at a distant location (away from the initial site)

• Molecular testing in desmoid tumor has following significance:
  • Presence of a positive test result helps aid, and in some cases, confirm the diagnosis of desmoid tumor
  • Result can help to exclude other tumors having similar histological features
  • It can help in determining the prognosis of the patient
  • Test results may help in making treatment decisions in some cases

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