Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP)


A smooth muscle tumour of the uterine body, the visceral adnexa, or the uterine ligaments, which bears features that preclude an unequivocal diagnosis of leiomyosarcoma, but that do not fulfill the criteria for leiomyoma or its variants, and raises concern that the neoplasm may behave in a malignant fashion (Kurman, R. J., 2014, Patel, V., 2020).

Synonym: Atypical smooth muscle neoplasm (Kurman, R. J., 2014).


There appears to be a universal agreement that the condition is rare, however exact data is lacking, possibly due to varying pathologic diagnostic criteria. Patient age at presentation appears similar to myomas (Ip, P. P., et al, 2010, Zheng, Y. Y. et al, 2020).

Clinical Image

Similar to myomas:

  • Abnormal vaginal bleeding.
  • Anemia.
  • Pelvic mass.
  • Pressure symptoms (Ip, P. P., et al, 2010, Oh, J., et al, 2019).


Ultrasound and MRI have been used extensively in an effort to distinguish among leiomyomata, leiomyosarcomata and even STUMP. Understanding the pathology behind these conditions, it shouldn’t come as a surprise that there is difficulty in setting pathognomonic features for each one (Oh, J., et al, 2019).

STUMP, consuming almost the entirety of the uterine body.

The following chart may be helpful when trying to establish a differential diagnosis:

SizeVariableVariableUsually already large when found
BordersRegularRegularCould be irregular
EchogenicityIsoechogenic or mixedIsoechogenic or mixedInhomogenous
CalcificationsMay appearAbsent
Acoustic ShadowsVariableAbsentAbsent
Gynecological symptomsMay appearUsually yesUsually yes
Anechogenic areasMay appearYesYes, irregular
VascularizationCircumferential and may even be intralesionalCircumferential and intralesionalCircumferential and intralesional
(Woźniak, A., & Woźniak, S., 2017)(Cotrino, I., et al, 2020)(Ludovisi, M., et al, 2019)
Ultrasound characteristics of uterine smooth muscle tumors.
STUMP Doppler
The same case as above, demonstrating circumferential as well as intralesional vascularization.


Total hysterectomy provides the definite surgical treatment in cases of STUMP (Zheng, Y. Y., et al., 2020).

Oncological follow-up is suggested.

  • first three years -> every three months
  • 4th and 5th year -> every six months
  • after 5 years -> annual surveillance

STUMPs may recur as STUMPs or as leiomyosarcomas.

* If the diagnosis of a STUMP arises after a myomectomy where the tumor has been sufficiently excised, fertility preservation is possible, however it is imperative that both the gynecologist and the patient should remain vigilant for the danger of recurrence (Ip, P. P., et al, 2010).


After adequate treatment prognosis may be excellent. (Oh, J., et al, 2019). Recurrence is a threat, but it only seems to occur in uterine preservation surgeries (Zheng, Y. Y., et al., 2020).


  • Oh, J., Park, S. B., Park, H. J., & Lee, E. S. (2019). Ultrasound Features of Uterine Sarcomas. Ultrasound quarterly35(4), 376–384.
  • Zheng, Y. Y., Liu, X. B., Mao, Y. Y., & Lin, M. H. (2020). Smooth muscle tumor of uncertain malignant potential (STUMP): a clinicopathologic analysis of 26 cases. International journal of clinical and experimental pathology13(4), 818–826.
  • Kurman, R. J. (2014). Who classification of tumours of female reproductive organs. International Agency for Research on Cancer.
  • Patel, V., Xing, D., Feely, M., & Schoolmeester, J. K. (2020). Smooth Muscle Tumors of the Visceral Adnexal and Uterine Ligaments and Adnexal Connective Tissue: A Clinicopathologic Study of 67 Cases. International journal of gynecological pathology : official journal of the International Society of Gynecological Pathologists39(1), 55–67.
  • Ip, P. P., Tse, K. Y., & Tam, K. F. (2010). Uterine smooth muscle tumors other than the ordinary leiomyomas and leiomyosarcomas: a review of selected variants with emphasis on recent advances and unusual morphology that may cause concern for malignancy. Advances in anatomic pathology17(2), 91–112.
  • Cotrino, I., Carosso, A., Macchi, C., Baima Poma, C., Cosma, S., Ribotta, M., Viora, E., Sciarrone, A., Borella, F., & Zola, P. (2020). Ultrasound and clinical characteristics of uterine smooth muscle tumors of uncertain malignant potential (STUMPs). European journal of obstetrics, gynecology, and reproductive biology251, 167–172.
  • Ludovisi, M., Moro, F., Pasciuto, T., Di Noi, S., Giunchi, S., Savelli, L., Pascual, M.A., Sladkevicius, P., Alcazar, J.L., Franchi, D., Mancari, R., Moruzzi, M.C., Jurkovic, D., Chiappa, V., Guerriero, S., Exacoustos, C., Epstein, E., Frühauf, F., Fischerova, D., Fruscio, R., Ciccarone, F., Zannoni, G.F., Scambia, G., Valentin, L. and Testa, A.C. (2019), Imaging in gynecological disease (15): clinical and ultrasound characteristics of uterine sarcoma. Ultrasound Obstet Gynecol, 54: 676-687.
  • Woźniak, A., & Woźniak, S. (2017). Ultrasonography of uterine leiomyomas. Przeglad menopauzalny = Menopause review16(4), 113–117.

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