Myxoid uterine leiomyoma

There is a large well-circumscribed lobulated and multiloculated soft tissue mass within the myometrium of the uterine isthmus. It appears of intermediate signal intensity on T1WI with areas of high signal (cystic hemorrhage), high signal on T2WI with sediment of the low signal within the cystic areas indicating hemosiderin deposits. A peripheral rim of low signal is noted on all sequences mainly on  T2WI. The postcontrast sequences show an intense and relatively heterogeneous enhancement except for the central areas of cystic haemorrahge which remain hypointense.

Focal thickening of the posterior uterine junctional zone seen as an inhomogeneous low signal intensity on T2 (thickness=25 mm) with multiple foci of high signal intensity. Multiple punctate fibroids of low signal T2WI are noted within the myometrium. 

Both ovaries appear normal, containing follicles with minimal effusion in the pouch of Douglas.

Macroscopically: well-limited oval mass with regular contours, measuring 7 x 6 cm, of soft consistency and translucent appearance, with areas of hemorrhagic changes.

Microscopically: This mass shows a mesenchymal proliferation with amorphous and myxoid stroma dissociating smooth muscle cells.

This myxoid and edematous material, of heterogeneous density, contains the remnants of smooth muscle cells often reduced to pale and small nuclei.
On the periphery, this proliferation of fasciculate architecture is composed of fusiform smooth muscle fibers with ill-defined limits and abundant eosinophilic cytoplasm. The nuclei are elongated with "end of cigar" appearance                                      

Conclusion: a histological aspect of a myxoid uterine leiomyoma with no histological signs of malignancy.