JAZF1–SUZ12 endometrial stromal sarcoma forming subserosal masses with extraordinary uptake of fluorodeoxyglucose on positron emission tomography: a case report

BACKGROUND: Low-grade endometrial stromal sarcoma (ESS) is rare mesenchymal neoplasm, recently specified as harboring JAZF1–SUZ12 rearrangement. Typical JAZF1–SUZ12 ESS is slow growing, in which high uptake of fluorodeoxyglucose (FDG) on positron emission tomography (PET) and subserosal masses are quite unusual. CASE PRESENTATION: A 69-year-old Japanese woman complained of urinary incontinence. Pelvic magnetic resonance imaging showed uterine lesions composed of (1) a 9 × 8 × 7-cm mass protruding from the right-anterior wall, (2) a 4.5-cm mass attached to the right-posterior wall, and (3) a 6.5-cm intramural mass in the fundus. FDG-PET demonstrated maximum standardized uptake value of 13.28 confined to the two subserosal masses (1 & 2) in contrast to no uptake of the intramural mass (3). She was diagnosed with a high-grade uterine sarcoma concomitant with leiomyomas and underwent total hysterectomy with bilateral salpingo-oophorectomy and pelvic lymphadenectomy. The removed uterus had three tumors—two in the right-anterior and right-posterior subserosa, respectively, and the remaining in the fundal myometrium. Microscopically, the three tumors shared morphologic features characterized by neoplastic cells similar to proliferative-phase endometrial stromal cells, in which neither round-cell component, pleomorphism, nor high mitotic activity was recognized. Nuclear cyclin D1 immunostaining was identified 50% of neoplastic cells in the two subserosal tumors (1 &2) whereas < 1% positive cells in the intramural component (3). Reverse transcriptase-polymerase chain reaction showed the same-sized electrophoretic bands indicating JAZF1–SUZ12 gene fusion shared by the three uterine tumors and a focal tumor extension into the extrauterine vein. The patient is alive without evidence of recurrence at 14 months after surgery. CONCLUSIONS: Pathologists and clinicians should not exclude the possibility of JAZF1–SUZ12 ESS even when uterine subserosal masses demonstrate extraordinary FDG uptake on PET. Molecular analysis is helpful for diagnostic confirmation of JAZF1–SUZ12 ESS with a complex growth pattern.