Hydropic leiomyoma: A radiologic pathologic correlation of a rare uterine tumor

Abstract

Hydropic leiomyoma is a rare leiomyoma subtype composed of a conspicuous zonal watery edematous stroma that causes compartmentalization of the smooth muscle cells. It exhibits atypical imaging features which can mimic malignancy, so differential diagnosis with malignant uterine tumors such as leiomyosarcoma is crucial for treatment decisions and patient follow-up. We describe the case of a 54-year-old postmenopausal woman presenting with a fast-growing abdominopelvic tumor associated with abdominal bloating, urinary frequency, and metrorrhagia. Radiologic evaluation depicted a voluminous, well-circumscribed, slightly lobulated, heterogeneous mass with mixed solid and cystic components arising from the uterus. Given the postmenopausal patient status, size of the tumor, and uncertainty about a possible malignant origin, an uneventful total abdominal hysterectomy with bilateral adnexectomy was performed as definitive treatment. However, as it is common practice in our institution, a second opinion report of the previous MRI was done before surgery, with the proposed diagnosis being hydropic leiomyoma. Pathologic examination of the surgical specimen revealed a large subserosal tumor with nodules separated by empty spaces and cysts due to watery exudate. Histologically, it was a mesenchymal neoplasm with trabecular and nested architecture, with tumor cells separated by watery fluid without mitosis or necrosis, securing the diagnosis of a hydropic leiomyoma.

Keywords: Atypical leiomyoma; Hydropic leiomyoma; Leiomyoma; Leiomyosarcoma; Uterus.

Fig. 1

Axial T2-weighted MRI of the pelvis reveals that the mass has a uterine origin, as depicted by the presence of the "claw sign" (arrows) that indicates a subserosal growing pattern. The tumor shows dominant high signal intensity with a well-defined hypointense border.

Fig. 2

Sagittal T2-weighted MRI shows a well-defined encapsulated ovoid tumor compressed by the sacral promontory. The tumor is heterogeneous and predominantly cystic. A solid cord-like component with intermediate to low T2 signal intensity is seen in the lower aspect of the mass. Signal voids are also depicted on T2-WI.

Fig. 3

Axial T1 weighted image reveals a hypointense mass that is indistinguishable from the uterus. Areas of high T1 signal intensity, representing hemorrhage or fat, were absent.

Fig. 4

Axial (a and b) and sagittal (c) T1 postcontrast weighted images show a well-demarcated, predominantly cystic mass. Marked contrast enhancement of the inferior aspect of the tumor, corresponding to its solid area, is seen (arrows).

Fig. 5

Right (a) and left (b) ovaries are documented (arrows) with normal postmenopausal characteristics. The mass is separated from the ovaries, excluding an ovarian origin.

Fig. 6

Gross features of hydropic leiomyoma (a, b). Subserosal well-circumscribed tumor with multiple, irregular, yellow-tan nodules, separated by empty spaces and cysts due to watery exudate, intersected with whorled, white and firm areas.

Fig. 7

H&E features of the hydropic leiomyoma: Mesenchymal neoplasm with trabecular and nested architecture, with tumor cells separated by watery fluid (edema) (a–c), with transition to conventional areas with fascicles of monotonous spindle cells without atypia, with indistinct cell borders, eosinophilic cytoplasm and cigar-shaped nuclei (d).