Smooth muscle tumor of uncertain malignant potential (STUMP) - clinico-pathomorphological analysis of the cases and literature review

Objectives: This retrospective study was designed to evaluate the clinical and pathological features and outcomes of patients diagnosed with uterine smooth muscle tumor of uncertain malignant potential (STUMP). Material and methods: Ten patients diagnosed with uterine STUMP and seen between 2008 and 2011 at the Memorial Cancer Center - Institute of Oncology in Warsaw were identified using the institution databases. Variables of interest included histopathological details, age at diagnosis, types of treatment and recurrence rate. Results: The mean age at diagnosis was 41 years (range 25-56 years). The mean follow-up time was 16 months (range 4-29 months). Diameter of the tumors ranged from 3 to 29 cm. Uterine bleeding was the second most frequent symptom observed in this cohort. In three cases conservative procedure was performed, whereas in other patients hysterectomy was performed. No recurrence was observed during the follow-up period. In all tumors mitoses were less than 10 per 10/hpf, atypia of middle or severe type, and in 3 cases necrosis was observed. In half of the tumors expression of TP53 was found, and value of MIB 1 was estimated at 2-35%. Conclusions: STUMP should be diagnosed by experienced pathologists due to the fact that they are often misdiagnosed as leiomyosarcornas. Clinical behavior of these tumors allows to consider a conservative management in patients wishing to preserve fertility