CASE 12733 Published on 30.09.2015

Uterine smooth muscle tumour of uncertain malignant potential: an entity difficult to diagnose

Section

Genital (female) imaging

Case Type

Clinical Cases

Authors

Xiropotamou ON¹, Tsili AC¹, Vrekousis Th², Evagelou Ch², Maliakas V¹, Argyropoulou MI¹

(1) Department of Clinical Radiology
(2) Department of Obstetrics and Gynaecology
Medical School,
University of Ioannina,
45110, Ioannina, Greece.
Email: a_tsili@yahoo.gr, atsili@cc.uoi.gr

Patient

48 years, female

Categories

Area of Interest Genital / Reproductive system female ; Imaging Technique MR, MR-Diffusion/Perfusion

Procedure Comparative studies ; Special Focus Neoplasia ;

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Clinical History

A 48-year-old woman was referred for abnormal vaginal bleeding of one year duration. Transvaginal sonography showed a large, heterogeneous, hypoechoic uterine mass, involving mainly the myometrium. Serum tumoral markers were normal. Diagnostic dilatation and curettage was inconclusive, due to the presence of necrotic material. MRI of the pelvis followed.

Imaging Findings

MRI revealed the presence of a large, heterogeneous myometrial uterine mass, protruding into the endometrial cavity and measuring 86 x 68 x 72 mm in dimensions (Figure 1). The lesion was inhomogeneous, mainly hyperintense on T2WI (Figure 1b), with areas of high signal on T1WI (Figure 1a), the latter suggestive of the presence of haemorrhage. No restricted diffusion was seen on the diffusion-weighted images (Figures 1c, d). The mass showed heterogeneous enhancement after gadolinium administration (Figure 1e). Neither tumour extension into the cervix nor pelvic lymphadenopathy was revealed.

Discussion

Histology following total abdominal hysterectomy revealed the presence of uterine smooth muscle tumour of uncertain malignant potential.
Smooth muscle tumours of the uterus are benign and malignant [1-4]. The main representative of the benign and malignant category is leiomyoma and leiomyosarcoma, respectively [1-4]. On the other hand, there is a peculiar category, described as smooth muscle tumours of uncertain malignant potential (STUMP), in which the degree of malignancy pathologically is between leiomyoma and leiomyosarcoma [6-11]. The term “STUMP” comprises a heterogeneous group of rare tumours. The histologic diagnosis is often challenging. Histologic criteria distinguishing these neoplasms from benign leiomyomas include coagulative cell necrosis, moderate to severe cytologic atypia and numerous mitotic figures (Stanford). Among these, the factor strongly associated with malignant behaviour seems to be coagulative cell necrosis, characterized by an abrupt transition between viable cells and necrotic areas [6-10].
The MRI characteristics for these tumours are non-specific, closely resembling those of leiomyomas and leiomyosarcomas. Tanaka et al in a retrospective study of 24 smooth muscle uterine tumours concluded that the presence of more than 50% high signal on T2WI, of small high-signal areas on T1WI (probably representing areas of haemorrhage) and heterogeneous contrast enhancement, with unenhanced pockets (most probably representing areas of necrosis) were considered as more suggestive of the diagnosis of SMTUMPs and leiomyosarcomas [6].
Diffusion-weighted imaging may have an important complementary role in the characterization of myometrial tumours [12-14]. Thomassin-Naggara et al in a retrospective study of 51 myometrial tumours reported an overall accuracy of 92.4% in their characterization, by combining T2-weighted, high b value and ADC features. More specifically, in tumours with an intermediate T2-weighted and high b1, 000 signal intensity, an ADC value lower than 1.23 was considered as predictive of malignancy [14].
STUMPs are usually clinically benign but, in some cases, recurrence may occur. The reported time of recurrence varies between 15 months to 9 years, but a few data are available in the literature. Recurrences behave in a low-grade malignant fashion, following a disease-free interval and with a prolonged survival, even when they recur as leiomyosarcomas. Sites of recurrence include the pelvis, abdomen, liver, lungs, lymph nodes, humerus, retroperitoneum and uterus, if hysterectomy is not performed [6-11].
No standard protocols for the management of patients with suspected STUMP exist. Surveillance of these patients should be close and long-term. Close multidisciplinary management is mandatory.

Differential Diagnosis List

Smooth muscle tumour of the uterus of uncertain malignant potential

Leiomyoma

Leiomyosarcoma

Adenomyosis

Focal myometrial contraction

Final Diagnosis

Smooth muscle tumour of the uterus of uncertain malignant potential

References

[1] Murase E, Siegelman E, Outwater E, et al (1999) Uterine leiomyomas: Histopathologic features, MR imaging findings, Differential diagnosis and treatment. Radiographics 19:1179-1197 (PMID: 3753623)

[2] Shah S, Jagannathan J, Krajewski K, et al (2012) Uterine sarcomas: Then and now. AJR 199:213–223 (PMID: 22733915)

[3] Sahdev A, Sohaib S, Jacobs I, et al (2001) MR imaging of uterus sarcomas. AJR 177:1307-1311 (PMID: 11717072)

[4] Cornfeld D, Israel G, Martel M, et al (2010) MRI appearance of mesenchymal tumors of the uterus. Eur J Radiol 74:241-249 (PMID: 19349135)

[5] Clement P (2000) The pathology of uterine smooth muscle tumors and mixed endometrial stromal tumors: A selective review with emphasis on recent advances. Int J Gynecol Pathol 19:39-55 (PMID: 10638452)

[6] Tanaka Y, Nishida M, Tsunoda H, et all (2004) Smooth muscle tumors of uncertain malignant potential and leiomyosarcomas of the uterus: MR findings. J Magn Reson Imaging 20:998-1007 (PMID: 15558559)

[7] Dall\'Asta A, Gizzo S, Musarò A, et al (2014) Uterine smooth muscle tumors of uncertain malignant potential (STUMP): pathology, follow-up and recurrence. Int J Clin Exp Pathol 15;7(11):8136-8142 (PMID: 25550862)

[8] Deodhar KK, Goyal P, Rekhi B, et al (2011) Uterine smooth muscle tumors of uncertain malignant potential and atypical leiomyoma: A morphological study of these grey zones with clinical correlation. Indian J Pathol Microbiol 54:706-711 (PMID: 22234095)

[9] Vilos GA, Marks J, Ettler HC, et al (2012) Uterine smooth muscle tumors of uncertain malignant potential: diagnostic challenges and therapeutic dilemmas. Report of 2 cases and review of the literature. J Minim Invasive Gynecol 19:288-295 (PMID: 22546421)

[10] Ip PP, Cheung AN, Clement PB (2009) Uterine smooth muscle tumors of uncertain malignant potential (STUMP): a clinicopathologic analysis of 16 cases. Am J Surg Pathol 33:992-1005 (PMID: 19417585)

[11] Canciani GN, Burbos N, Duncan TJ, et al (2012) Late presentation of metastatic smooth muscle neoplasm of the uterus with low malignant potential. J Gynecol Oncol 23:69-71 (PMID: 22355470)

[12] Tamai K, Koyama T, Saga T, et al (2008) The utility of diffusion-weighted MR imaging for differentiating uterine sarcomas from benign leiomyomas. Eur Radiol 18:723–730 (PMID: 17929022)

[13] Namimoto T, Yamashita Y, Awai K, et al (2009) Combined use of T2-weighted and diffusion-weighted 3-T MR imaging for differentiating uterine sarcomas from benign leiomyomas. Eur Radiol 19:2756–2764 (PMID: 19504102)

[14] Thomassin-Naggara I, Dechoux S, Bonneau C, et al (2013) How to differentiate benign from malignant myometrial tumours using MR imaging. Eur Radiol 23:2306–2314 (PMID: 23563602)

Case information

URL:	https://www.eurorad.org/case/12733
DOI:	10.1594/EURORAD/CASE.12733
ISSN:	1563-4086

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This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

MRI examination

Sagittal Τ2-weighted image demonstrates a large myometrial uterine mass, mainly hyperintense, extending into the endometrial cavity. No signs of cervical invasion are seen.