What is the role of genetics in the etiology of soft-tissue tumors?

Updated: Dec 03, 2018
  • Author: Vinod B Shidham, MD, FRCPath; Chief Editor: Omohodion (Odion) Binitie, MD  more...
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Answer

Good evidence exists suggesting that certain genetic disorders and gene mutations are predisposing factors for some benign and malignant soft-tissue tumors. The NF1 gene in neurofibromatosis is a classic example, predisposing patients to multiple neurofibromas with a proclivity for malignant transformation. Many tumor suppressor genes, oncogenes, and cytogenetic defects are now associated with various soft-tissue sarcomas. Other clinical risk factors account for a small proportion of soft tissue malignancies.

Various cytogenetic abnormalities (see Table 1 below) have been reported to play a significant role in diagnosis, and in the future, some of these abnormalities may become therapeutically significant.

Table 1. Selected Characteristic Cytogenetic Aberrations in Soft-Tissue Tumors (Open Table in a new window)

Benign Soft-Tissue Tumors

Characteristic

Cytogenetic Events

Frequency

Benign schwannoma

Monosomy 22

50%

Desmoid tumor

Trisomy 8

25%

 

Deletion of 5q

10%

Lipoblastoma

Rearrangement of 8q

>25%

Lipoma, solitary

Rearrangement of bands 12q14-15

75%

 

Rearrangement of 6p

10%

 

Deletion of 13q

10%

Uterine leiomyoma

t(12;14)(q15;q24)

20%

 

Deletion of 7q

15%

 

Trisomy 12

10%

Malignant Soft-Tissue Tumors

Characteristic

Cytogenetic Events

Frequency

Clear cell sarcoma

t(12;22)(q13;q12)

>75%

Dermatofibrosarcoma protuberans

Ring chromosome 17

>75%

Ewing sarcoma

t(11;22)(q24;q12)

95%

Extraskeletal myxoid chondrosarcoma

t(9;22)(q31;q12)

50%

Liposarcoma, myxoid

t(12;16)(q13;p11)

75%

Liposarcoma, well differentiated

Ring chromosome 12

80%

Alveolar rhabdomyosarcoma

t(2;13)(q35;q14)

80%

Synovial sarcoma

t(X;18)

95%

Specific translocations involving selected genes have been observed. One of these, the t(X;18) translocation in synovial sarcoma, results in fusion of the SYT gene from chromosome 18 to either of two highly homologous genes at Xp11, SSX1 or SSX2.SYT-SSX fusion transcript may be detected by reverse transcriptase-polymerase chain reaction (RT-PCR) assay, using a cytologic specimen from FNA biopsy (FNAB), histologic material from paraffin block, or frozen material.


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