Primary gastric synovial sarcoma: molecular diagnosis and prediction of prognosis

Abstract

A 42-year-old Japanese woman complained of upper abdominal pain. Endoscopic examination demonstrated an elevated lesion in the body of the stomach, and a biopsy specimen demonstrated proliferation of atypical spindle cells. She underwent partial gastrectomy; the resected tumor measured 3.5 × 2.8 × 1.2 cm in size. Histological examination disclosed the haphazard proliferation of spindle cells in the mucosa mixed with less prominent epithelioglandular component. The spindle cells were positive for cytokeratin, vimentin, EMA and CD99, but not for KIT, DOG1, desmin or S100. Reverse transcription-polymerase chain reaction using paraffin sections amplified a SYT-SSX1 chimera transcript. A diagnosis of synovial sarcoma was made. There has been no sign of recurrence or metastasis for 6 years after the operation. Synovial sarcoma in the stomach is very rare. Since differential diagnosis of synovial sarcoma from carcinosarcoma and mesenchymal tumors is critical for the treatment and prediction of prognosis, accurate diagnosis with molecular analysis is essential.

“Wild type” GIST: Clinicopathological features and clinical practice

“…GIST should be distinguished from other mesenchymal neoplasms of the gastrointestinal tract. The differential diagnosis includes leiomyoma/leiomyosarcoma, Schwannoma, desmoid tumor, inflammatory myofibroblastic tumor and synovial sarcoma . Neoplastic cells in these tumors usually present spindle morphology.…”

Abdominal monophasic synovial sarcoma is a morphological and immunohistochemical mimic of gastrointestinal stromal tumour

“…Another difference between these previously reported oesophageal and gastric synovial sarcomas is that the median patient age of the oesophageal cases (25 years) was lower than that of the gastric cases (52 years); the median age of our two gastric synovial sarcoma patients was 42 years. All 13 previously reported gastric synovial sarcomas that were immunostained for CD117 and the single reported duodenal synovial sarcoma were reported not to express the protein . Furthermore, the two gastric cases that had been immunostained for DOG1 were also reported not to show expression of this protein .…”

“…It is also noted that both CD117 expression and DOG1 expression by synovial sarcoma arising in soft tissues have been well described . The patient prognoses associated with the previously reported primary gastrointestinal synovial sarcomas varied, but it has been suggested that tumours of larger size and/or with poorer differentiation have a worse outcome…”

“…There have only been a small number of reported cases of synovial sarcoma arising within the organs of the luminal gastrointestinal tract. These cases arose within the oesophagus or stomach or, in one case, the duodenum . The largest published case series of primary gastrointestinal synovial sarcomas comprised 10 gastric cases, although only seven had the diagnosis confirmed by demonstration of a fusion transcript with reverse transcription PCR .…”

“…Synovial sarcoma may rarely arise inside or around the abdominal cavity . Most primary abdominal synovial sarcomas are located within the retroperitoneum or pelvis, but an even smaller number of synovial sarcomas have been reported to actually arise within luminal gastrointestinal tract organs . Synovial sarcoma may show a variety of morphological appearances, whether in its biphasic or in its monophasic form.…”