The objective of this study was to investigate the clinicopathological features and factors associated with recurrence in patients with uterine smooth muscle tumor of uncertain malignant potential (STUMP).Methods
Forty-six cases diagnosed between 2000 and 2014 from 2 tertiary centers underwent blind slide review. Initial diagnosis included smooth muscle tumors with equivocal diagnosis, STUMPs, and cases that were named as leiomyosarcomas (LMS) or low-grade LMS despite not fulfilling the Stanford criteria.Results
In total, 21 patients with a final diagnosis of STUMP were available. Fifteen (68.1%) of 22 patients with an initial diagnosis of STUMP, 4 (22.2%) of 18 cases with an equivocal smooth muscle tumor diagnosis, and 2 (33.3%) of 6 cases with an initial diagnosis of LMS were interpreted as STUMP after slide review. The mean age at diagnosis was 43 years (range, 20–64 years). The mean follow-up time was 65.9 months (range, 10–154 months). Four patients (19.0%) developed recurrent disease. Recurrent tumors were LMS in 3 patients (75%). One patient (4.8%) with recurrence succumbed to disease. There was no difference in patients' age (P = 1.0) or type of initial surgery (uterus conserving versus hysterectomy) (P = 0.57) between patients who recurred and did not recur.Conclusions
Uterine STUMPs can harbor significant uncertainty regarding the original diagnosis and clinical outcomes. Recurred cases may have an aggressive clinical course associated with multiple relapses and death. Uterine mesenchymal tumors other than ordinary myomas and overt sarcomas deserve a second opinion in centers with experience because the real diagnosis may vary significantly.