Abstract
Fluorescence in situ hybridization (FISH) and reverse-transcription polymerase chain reaction (RT-PCR) analysis may be used for the diagnosis of synovial sarcoma (SS), particularly of the poorly differentiated type. While the majority of the studies report that the SYT FISH probe is considered to be break-apart in SS, with two orange and two green signals, the SYT probe in the present case of a 52-year-old male patient with pulmonary SS displayed orange and green signal separation, along with SYT orange signal amplification. RT-PCR was used to verify that the SYT gene amplification was another form of expression of SYT-SSX gene fusion t(X; 18)(p11; q11). In this case, the tumour sample obtained by biopsy was small; therefore, the definitive diagnosis of poorly differentiated SS originating from the lung with SYT gene amplification was confirmed by FISH and RT-PCR. Therefore, these mature biomarkers, which are available as immunohistochemical stains in the molecular pathology laboratory, may help pathologists to diagnose intractable soft tissue tumours based only on small cytological specimens.