Smooth muscle tumours of the uterus: MR imaging malignant predictive features-a 12-year analysis in a referral hospital in Portugal.

PURPOSE: To evaluate the magnetic resonance imaging (MRI) features that may help distinguish leiomyosarcomas from atypical leiomyomas (those presenting hyperintensity on T2-W images equal or superior to 50% compared to the myometrium). MATERIALS AND METHODS: The authors conducted a retrospective single-centre study that included a total of 57 women diagnosed with smooth muscle tumour of the uterus, who were evaluated with pelvic MRI, between January 2009 and March 2020. All cases had a histologically proven diagnosis (31 Atypical Leiomyomas-ALM; 26 Leiomyosarcomas-LMS). The MRI features evaluated in this study included: age at presentation, dimension, contours, intra-tumoral haemorrhagic areas, T2-WI heterogeneity, T2-WI dark areas, flow voids, cyst areas, necrosis, restriction on diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) values, signal intensity and heterogeneity after contrast administration in T1-WI, presence and location of unenhanced areas. The association between the MRI characteristics and the histological subtype was evaluated using Chi-Square and ANOVA tests. RESULTS: The MRI parameters that showed a statistically significance correlation with malignant histology and thus most strongly associated with LMS were found to be: irregular contours (p < 0.001), intra-tumoral haemorrhagic areas (p = 0.028), T2-WI dark areas (p = 0.016), high signal intensity after contrast administration (p = 0.005), necrosis (p = 0.001), central location for unenhanced areas (p = 0.026), and ADC value lower than 0.88 × 10-3 mm2/s (p = 0.002). CONCLUSION: With our work, we demonstrate the presence of seven MRI features that are statistically significant in differentiating between LMS and ALM.

Differentiation of Uterine Leiomyosarcoma from Atypical Leiomyoma: Diagnostic Accuracy of Qualitative MR Imaging Features and Feasibility of Texture Analysis.

PURPOSE: To investigate whether qualitative magnetic resonance (MR) features can distinguish leiomyosarcoma (LMS) from atypical leiomyoma (ALM) and assess the feasibility of texture analysis (TA). METHODS: This retrospective study included 41 women (ALM = 22, LMS = 19) imaged with MRI prior to surgery. Two readers (R1, R2) evaluated each lesion for qualitative MR features. Associations between MR features and LMS were evaluated with Fisher's exact test. Accuracy measures were calculated for the four most significant features. TA was performed for 24 patients (ALM = 14, LMS = 10) with uniform imaging following lesion segmentation on axial T2-weighted images. Texture features were pre-selected using Wilcoxon signed-rank test with Bonferroni correction and analyzed with unsupervised clustering to separate LMS from ALM. RESULTS: Four qualitative MR features most strongly associated with LMS were nodular borders, haemorrhage, "T2 dark" area(s), and central unenhanced area(s) (p ≤ 0.0001 each feature/reader). The highest sensitivity [1.00 (95%CI:0.82-1.00)/0.95 (95%CI: 0.74-1.00)] and specificity [0.95 (95%CI:0.77-1.00)/1.00 (95%CI:0.85-1.00)] were achieved for R1/R2, respectively, when a lesion had ≥3 of these four features. Sixteen texture features differed significantly between LMS and ALM (p-values: <0.001-0.036). Unsupervised clustering achieved accuracy of 0.75 (sensitivity: 0.70; specificity: 0.79). CONCLUSIONS: Combination of ≥3 qualitative MR features accurately distinguished LMS from ALM. TA was feasible. KEY POINTS: • Four qualitative MR features demonstrated the strongest statistical association with LMS. • Combination of ≥3 these features could accurately differentiate LMS from ALM. • Texture analysis was a feasible semi-automated approach for lesion categorization.

Leiomioma atípico / Atypical leiomyoma

Os autores relatam o caso de um leiomioma atípico ocasionalmente identificado em uma mulher de 45 anos submetida a histerectomia por sangramento uterino anormal. O leiomioma atípico, também conhecido como leiomioma bizarro ou simplástico, é um tumor pouco comum, sendo responsável por 0,5% a 1,0% das neoplasias mesenquimais uterinas. É caracterizado pela presença de células gigantes com múltiplos núcleos pleomórficos e cromatina grumosa. O seu comportamento biológico depende do seu índex mitótico e da presença de necrose tumoral. Paralelamente ao relato do caso, são discutidos os achados histopatológicos e clínicos do leiomioma atípico e a importância do seu diagnóstico diferencial com neoplasias malignas uterinas como o leiomiossarcoma.

The authors report a case of atypical leiomyoma occasionally identified in a woman of 45 who underwent hysterectomy for abnormal uterine bleeding. Atypical leiomyoma, also known as symplastic or bizarre leiomyoma, is an uncommon tumor accounting for 0.5-1.0% of uterine mesenchymal neoplasms. It is characterized by the presence of giant cells with multiple pleomorphic nuclei and granular chromatin. Its biological behavior depends on their mitotic index and the presence of tumor necrosis. Parallel to the case report we discuss the clinical and histopathological findings of atypical leiomyoma and the importance of its differential diagnosis with malignant uterine neoplasms such as leiomyosarcoma.