Fluorescence in Situ Hybridization (FISH) for Differential Diagnosis of Soft Tissue Sarcomas

Document Type : Research Articles


Department of Pathology, Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan.


Introduction:Soft tissue sarcomas are rare tumors comprising 1 percent of solid malignancies. The latest edition
of WHO soft tissue pathology lists 94 benign and malignant soft tissue tumors. Many of these show a large degree
of morphological overlap. Immunohistochemistry has been shown to be reliable in many cases for differential diagnosis
of lesions, although cytogenetic tests are considered the gold standard for many entities.Fluorescence in-situ hybridization
(FISH) is a cytogenetic technique that uses fluorescent probes that bind to only those parts of the chromosome which
have a high degree of sequence complementarity. Many soft tissue tumors show recurrent genetic mutations that are
now being used as diagnostic markers. Knowledge of the molecular identity allows prediction of behavior, prognosis
and treatment response. Objective:The aim of this study was to identify genetic mutations in soft tissue sarcomas using
FISH testing and to assess correlations with histological diagnosis. Material and methods:A total of 25 cases of different
soft tissue sarcomas diagnosed on histology with the help of immunohistochemical staining and for which FISH studies
were requested were included in this study. Three pathologists with a special interest in soft tissue sarcomas reviewed
the cases. FISH tests for EWS, the X:18 translocation, FOXO1 and MDM2 were respectively applied for 8 cases of
Ewing sarcoma, 8 cases of synovial sarcoma, 2 cases of rhabdomyosarcoma and 7 cases of dedifferentiated liposarcoma
and atypical lipomatous tumors/well differentiated liposarcomas. Results:EWS gene fusion was detected in 7 out of
8 cases of Ewing sarcoma and the X:18 translocation was positive in 3 of the 8 cases of synovial sarcoma. FOXO1
was not detected in either of the two rhabdomyosarcomas. MDM2 by FISH was detected in only one out of 5 cases of
atypical lipomatous tumors and 1 out of 2 dedifferentiated liposarcomas. Conclusion: FISH is a useful adjunct in the
diagnostic assessment of different types of soft tissue sarcomas. It is easy to set up, is relatively inexpensive and has
the ability to diagnose sarcomas with great accuracy, especially in cases which can not be accurately classified even
after thorough histological and immunohistochemical evaluation. It may play a very important role in the accurate
diagnosis and correct management of patients.


Main Subjects

Volume 19, Issue 3
March 2018
Pages 655-660
  • Receive Date: 05 April 2017
  • Revise Date: 27 December 2017
  • Accept Date: 27 January 2018
  • First Publish Date: 01 March 2018