Case Report: Giant anterior-wall uterine leiomyoma with cystic hydropic degeneration mimicking malignancy

Background Giant uterine leiomyomas with extensive cystic and hydropic degeneration are uncommon and can resemble uterine sarcoma or an adnexal malignancy clinically, radiologically and intraoperatively. Case presentation A woman in her 30s presented with six months of abdominal pain and progressive abdominal enlargement, followed by 15 days of bilateral pitting lower-limb oedema. Examination revealed a firm abdominopelvic mass corresponding to a 28–32-week gravid uterus. Contrast-enhanced computed tomography demonstrated an 18.8 × 12.0 × 19.1 cm complex solid-cystic lesion arising from the anterior uterine wall, with irregular enhancing septa, compression of the common iliac vessels and lower inferior vena cava, and distal ureteric compression causing mild hydroureteronephrosis. Leiomyoma with cystic degeneration was favoured, but leiomyosarcoma remained a radiological differential diagnosis. Exploratory laparotomy with tumour excision, hysterectomy, bilateral salpingo-oophorectomy and pelvic lymph-node dissection was performed. The encapsulated mass measured 22 × 20 × 10 cm at final gross examination and released approximately 3 L of blood-stained serous fluid. Frozen section showed a bland spindle-cell smooth-muscle tumour with extensive hyalinisation and cystic change; because of the abnormal gross appearance and limited sampling, a guarded impression favouring “atypical leiomyoma” was issued pending permanent sections. Extensive permanent sampling demonstrated interlacing fascicles of bland smooth-muscle cells with cystic hydropic degeneration and hyalinisation, without significant cytological atypia, mitotic figures or coagulative tumour-cell necrosis. The final diagnosis was giant leiomyoma with cystic hydropic degeneration and hyalinisation. At the 3-month follow-up, the patient remained well without clinical evidence of recurrence. Conclusion Marked degeneration, blood-stained serous fluid and major pressure effects can make a benign leiomyoma appear malignant. Frozen-section uncertainty alone is not a justification for radical surgery. Integrated clinical, radiological and histopathological assessment should guide management, with particular attention to fertility and ovarian preservation in young women.