Detection of Inflammatory Myofibroblastic Tumor

Tropomyosin 3 (TMP3, also known as TRK or NEMl) gene located on chromosome lq25 encoding a 284 amino acid protein with coiled coil structure involved in the calcium-dependent actin-myosin interaction. This gene is the fusion partner of the ALK gene in the t(l 2)(q25 p23) translocation. This translocation seems to be the most common translocation associated with the inflammatory myofibroblastic tumor but it is also detected in other tumors such as the anaplastic large cell lymphoma discussed in a later section. 

Tropomyosin 4 (TMP4, tropomyosin fibroblast, non-musde type) gene is located on chromosome 19pl3 encodes a 248 amino acid protein with coiled coU structure, an alpha tropomyosin, a member of the actin filament-binding proteins family. This gene is the ALK gene fusion partner in the t(19 2)(pl3 p23) translocation. Depending on the location of breakpoints and the involved exons two fusion variants are described. 

The gene encoding the cysteinyl-tRNA synthetase enzyme (CARS) is a further fusion partner of the ALK gene in the t(2 11 2)(p23 pl5 q31) translocation described 

The detection of the above-mentioned chromosomal abnormalities can support the diagnosis of inflammatory myofibroblastic tumor, especially in atypical tumor locations or doubtful immunohistochemical profile. The association with HHV-8 vims is a further interesting aspect discussed in a later chapter. 

Method The method used is mRNA extraction from frozen or paraffin-embedded tissue or ENA cells, followed by RT-PCR. 

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