Huge Degenerated Fibroid Mimicking Hydatid Cyst of the Uterus: A Rare Diagnostic Dilemma

Abstract

Background: Uterine leiomyomas are among the most frequently encountered benign tumors in women of reproductive age. Although typically well-characterized on imaging, degenerative changes can alter their appearance and occasionally mimic more sinister or rare pathologies. One such rare mimic is a hydatid cyst, especially in endemic rural areas where humans have close contact with definitive hosts such as dogs. Hydatid disease involving the uterus is an exceptional rarity, and its clinical and imaging presentation can closely resemble that of a degenerating fibroid, leading to diagnostic ambiguity. Case Presentation: We report the case of a 34-year-old multiparous woman (Para 2, Living 2) who presented with complaints of lower abdominal pain and a palpable mass. She belonged to a rural agrarian background with frequent exposure to domestic dogs and cattle. Ultrasonography revealed a large heterogeneous solid-cystic mass arising from the uterine fundus, measuring approximately 10.7 × 6.8 × 10.5 cm, with internal septations and fluid components, raising a differential diagnosis of a cavitated fibroid or a hydatid cyst. Surgical management in the form of total abdominal hysterectomy with bilateral salpingectomy was undertaken. Gross pathological examination revealed multiple well-defined intramural masses ranging from 0.8 to 2.9 cm, without evidence of necrosis or hemorrhage. Microscopic examination confirmed leiomyomas with degenerative changes and revealed eosinophilic granular material suggestive of parasitic etiology. Empirical anti-helminthic therapy with albendazole was initiated. A full-body radiological screening showed no secondary lesions, and postoperative recovery was uneventful. The patient remains stable on regular follow-up. Conclusion: This case highlights a rare and intriguing diagnostic challenge where a huge degenerative fibroid closely mimicked a hydatid cyst both radiologically and histopathologically. In regions endemic to echinococcosis, especially among individuals with close animal contact, such mimics must be considered in the differential diagnosis. Accurate intraoperative assessment and histopathological correlation are essential to avoid misdiagnosis and to guide appropriate therapeutic intervention.