Clinical and reproductive outcomes of uterine smooth muscle tumor of uncertain malignant potential: a single-center retrospective study

Abstract

Objective: To evaluate the clinical outcomes, histopathological features, and obstetric and oncological outcomes of uterine smooth muscle tumor of uncertain malignant potential (STUMP).

Methods: We conducted a single-center, database review of patients with STUMP between January 2001 and December 2015. We investigated the clinical, operative, histopathologic, recurrence, and fertility outcomes of the included cases.

Results: Nineteen patients with STUMP were studied. Three were reclassified as sarcoma after slide review, and 16 patients were finally included in the study. The mean age was 45 years. Ki-67 expression was ≥10% in 25.0% of cases and 30% in the only recurrent case. Recurrence occurred 52 months after a diagnosis of STUMP in a 56-year-old female patient who underwent hysterectomy. Two of six patients who underwent myomectomy had fertility requirements, and both successfully delivered babies without recurrence. Recurrence was not related to mitosis, degree of atypia, or necrosis. There was also no relationship between type of surgery or surgical approach and recurrence.

Conclusions: Patients with STUMP warrant a pathological review process in centers with experience. Fertility-preservation is worth attempting, but young patients must be followed-up closely. Ki-67 might be a valuable marker predicting recurrence.

Keywords: Ki-67; Uterine smooth muscle tumor of uncertain malignant potential; fertility preservation; leiomyosarcoma; myomectomy; recurrence.

Figure 1.

Microscopic findings of cases that met the criteria for uterine smooth muscle tumor of uncertain malignant potential (STUMP). (a) Coagulative tumor cell necrosis was not found (hematoxylin and eosin (H&E; ×40). (b) Clear tumor margins, abundant cells, and obvious cellular atypia compared with the surrounding myometrium (H&E ×100). (c) Significant (moderate-severe) atypia (H&E ×400). (D) Mitotic index <10 mitoses per 10 high-power fields (H&E ×400).

Figure 2.

Microscopic findings of primary and recurrent lesions in a patient with recurrent uterine smooth muscle tumor of uncertain malignant potential (STUMP). (a) Coagulative tumor cell necrosis was not found (hematoxylin and eosin (H&E ×40). (b) Clear tumor margins, abundant cells, but no obvious cellular atypia compared with the surrounding myometrium (H&E ×100). (c) Minimal atypia: regular nuclear membrane, fine granules on staining, and small nucleoli (H&E ×400). (D) Mitotic index >15 mitoses per 10 high-power fields (HPFs) (H&E ×400). (e, f) Recurrent tumors: minimal atypia and mitotic index >15 mitoses per 10 HPFs, no histological progression (H&E ×400).