Hemorrhagic necrosis of omental cysts misdiagnosed as torsion of ovarian cysts: a case report and literature review.

Hemorrhagic necrosis of an omental cyst, although rare, should be considered in the differential diagnosis of acute abdomen in female patients, particularly when the clinical presentation mimics that of ovarian torsion. This case highlights the diagnostic challenges, as clinical signs, inflammatory markers (elevated WBC and CRP), tumour markers (such as CA125), and imaging findings may be misleading. Surgeons and gynaecologists should maintain a high index of suspicion for complicated omental cysts in patients presenting with acute lower abdominal pain and a pelvic mass, especially when imaging is inconclusive or atypical for adnexal pathology. Emergency laparoscopy remains crucial for accurate diagnosis and minimally invasive definitive management, leading to favourable outcomes.

Omental cysts are rare intra-abdominal lesions that are most commonly observed in children but are also found in adults, with a noted female predominance [ 1 , 5 ]. Their pathogenesis is most commonly attributed to abnormal dilatation, distortion, and obstruction of lymphatic vessels or blood vessels during embryonic development [ 3 ]. Histologically, they are classified as either simple cysts (lymphangiomas) or pseudocysts (secondary to trauma or inflammation) [ 6 ]. In the present case, the identification of a mesothelial lining (AE1/AE3+, Calretinin+) supported the diagnosis of a true cyst, possibly of lymphatic or mesothelial origin, although extensive inflammation and necrosis can obscure the original histological architecture. The clinical presentation of omental cysts is highly variable. Many lesions remain asymptomatic for prolonged periods [ 5 ]. When symptoms do occur, they are often chronic and nonspecific, typically resulting from the mass effect of an enlarging cyst. However, complications such as torsion, hemorrhage, infection, or rupture may lead to acute presentations, including abdominal pain, vomiting, fever, localized or diffuse abdominal tenderness, rebound tenderness, abdominal rigidity, and leukocytosis [ 7 , 8 , 9 ]. These clinical features can mimic peritonitis, and as a result, many cases are diagnosed during emergency surgery prompted by complication-related symptoms. The diagnosis of complicated omental cysts remains challenging due to their rarity and nonspecific clinical presentation. Our patient initially presented with acute lower abdominal pain, fever, localized and rebound tenderness, leukocytosis, and elevated C-reactive protein (CRP) — findings common to many acute abdominal conditions. At the referring hospital, a provisional diagnosis of pelvic inflammatory disease (PID) was made, which was plausible; however, the lack of clinical improvement following antibiotic therapy suggested an alternative cause.Upon arrival to our emergency department, a large palpable pelvic mass prompted reconsideration of the diagnosis. Ovarian cyst torsion was the primary preoperative consideration, supported by the sudden onset of severe pain, the mass’s size and location on physical exam and imaging, pelvic effusion, cervical motion tenderness, and markedly elevated CA125 levels. Although CA125 is often associated with ovarian malignancy, it can also be elevated in benign gynecologic conditions such as endometriosis, fibroids, PID, and in non-gynecologic peritoneal irritation. In this case, the elevated CA125 (243 U/mL) likely reflected extensive peritoneal inflammation secondary to hemorrhage and necrosis within the omental cyst rather than malignancy. The raised D-dimer level (4.36 µg/mL) further indicated an acute inflammatory or thrombotic process consistent with hemorrhagic and necrotic changes [ 10 ]. But the above may mislead clinicians toward malignancy or severe pelvic infection [ 11 , 12 , 13 ]. Despite advanced imaging, diagnosis can only confirmed by diagnostic operation, which also allowed definitive treatment.Key diagnostic clues that shifted suspicion away from a primary gynecologic origin included the absence of gynecologic symptoms such as abnormal vaginal discharge or recent sexual activity, negative serum HCG excluding pregnancy-related pathology, and unremarkable adnexal findings on imaging. Moreover, the mass appeared to displace rather than arise from pelvic organs. Imaging studies play a pivotal role in the evaluation of acute abdominal pain and pelvic masses. Computed tomography (CT) is often the imaging modality of choice in emergency settings. In this case, CT revealed a large multilocular cystic mass with internal septations and surrounding inflammatory changes; however, it failed to definitively determine the origin of the lesion, although its location superior to the bladder was noted. Typically, omental cysts appear on CT as well-defined, thin-walled, fluid-attenuation lesions; complications such as hemorrhage may increase attenuation, obscuring classical imaging features [ 14 , 15 ]. Ultrasound may also aid in detection, usually demonstrating a unilocular or multilocular anechoic or complex cystic mass; however, differentiating omental cysts from other cystic entities such as mesenteric, ovarian, or duplication cysts remains challenging [ 15 , 16 ]. In this case, the inability of preoperative imaging to accurately localize the origin of the cyst highlights a well-documented limitation, particularly when large cysts occupy the pelvis and mimic adnexal pathology. This case highlights the importance of including omental cysts in the differential diagnosis of acute pelvic pain in reproductive-aged women, particularly with complications. Numerous case reports have described omental cysts initially mistaken for appendicitis, diverticulitis, or, as in our case, ovarian torsion [ 17 , 9 , 18 , 19 ]. A structured diagnostic approach should include pelvic examination, pregnancy testing, and pelvic ultrasound, with close attention to the response to antibiotics. Failure to improve should prompt reconsideration of the diagnosis. When imaging reveals cystic masses displacing rather than involving pelvic organs, mesenteric or omental pathology should be considered. Timely surgical exploration is warranted in cases of clinical deterioration or diagnostic uncertainty. Laparoscopy was invaluable in the present case. This technique permitted direct inspection of the abdominal and pelvic organs, confirmed the normal appearance of the uterus and adnexa, and accurately identified the origin of the cyst as the greater omentum. Complete surgical excision was achieved via laparoscopy, which remains the gold standard treatment for symptomatic or complicated omental cysts [ 2 , 20 ]. During the preoperative consultation and surgical preparation, the patient and her family were informed of the potential need for conversion to laparotomy. Intraoperatively, laparoscopic exploration was first performed. Once the lesion was confirmed to be an omental cyst, the cyst wall was gently elevated. A puncture needle was then used to aspirate the cystic fluid to reduce its volume. The puncture site was carefully clamped to prevent leakage, and the cyst was placed into an endoscopic retrieval bag. Further aspiration was performed within the bag to minimize the size, and the intact cyst was completely removed through the laparoscopic port, adhering strictly to tumor-free principles.Laparoscopic resection offers numerous advantages, including reduced postoperative pain, shorter hospitalization, and expedited recovery, as evidenced by the discharge of our patient on the third postoperative day [ 20 ]. However, careful adherence to the tumor-free principle is essential during cyst removal. In cases where laparoscopic exploration reveals a large cyst, extensive adhesions, or significant intraoperative bleeding, timely conversion to laparotomy is warranted. Starting with laparoscopic exploration offers the patient a chance for minimally invasive surgery. Histopathological examination remains essential to establish a definitive diagnosis and exclude malignancy, although malignancy is rare in cases of omental cysts [ 5 ]. In this case, histology revealed a cystic structure composed of fibrous and adipose tissue, hemorrhage, necrosis, and inflammation, lined focally by mesothelial cells, with negative immunostaining for malignancy markers and a low Ki-67 proliferation index, confirming a benign complicated omental cyst. Following surgical intervention, our patient experienced complete resolution of symptoms and remained recurrence free during follow-up, highlighting the importance of timely recognition and definitive management of this rare but potentially complicated entity.

Omental cysts are rare intra-abdominal cystic lesions, with an estimated incidence ranging from 1 in 100,000 to 1 in 250,000 hospital admissions [ 1 ]. These lesions can originate from lymphatic, mesothelial, or enteric sources and are usually asymptomatic unless complications such as torsion, rupture, infection, or hemorrhage occur [ 2 ]. Owing to their rarity and nonspecific presentation, omental cysts are often misdiagnosed as adnexal masses, gastrointestinal duplication cysts, or other intra-abdominal cysts [ 3 , 4 ]. Laparoscopic exploration can clarify the source of the cyst, and surgical resection is the main treatment for omental cysts. Most patients have a good prognosis after surgical resection, but a few patients experience recurrence due to multiple cysts and incomplete surgical resection. This report details a rare case of hemorrhagic necrosis in an omental cyst misdiagnosed as ovarian torsion and reviews the literature to provide a useful reference for the management of similar acute abdominal presentations. A 32-year-old woman (gravida 2, para 1) with a history of one prior uncomplicated vaginal delivery and one first-trimester miscarriage managed conservatively, presented with a four-day history of paroxysmal pain and swelling in the right lower abdomen, worsening on the day of admission with fever (38.3 °C). Initially, the pain was mild, intermittent, and dull, so she did not seek medical attention. However, two days later, the abdominal pain worsened, becoming sharper and constant, she visited a local community hospital. Routine blood tests revealed a white blood cell (WBC) count of 10.47 × 10 9 /L (Neutrophils: 7.64 × 10 9 /L) and a C-reactive protein (CRP) level of 57.41 mg/L. A urine pregnancy test (β-hCG) was negative. Suspecting pelvic inflammatory disease, she was prescribed oral antibiotics, which provided no significant symptom relief. Upon arrival at our emergency department, the patient reported continuous, sharp pain localized to the right lower abdomen, worsened by movement and accompanied by a subjective sensation of fullness and discomfort. Physical examination revealed a distended abdomen with a palpable, soft, well-defined mass approximately 20 cm in diameter in the lower abdomen. The laboratory findings revealed leucocytosis (WBC 13.81 × 10 9 /L) and elevated CRP levels (121.38 mg/L). β-hCG was negative. An urgent abdominal computed tomography (CT) scan revealed a large, low-density mass measuring approximately 56 × 91 × 143 mm and situated superior to the bladder. The mass exhibited relatively uniform density, multilocular septations, and slightly blurred surrounding fat planes. No enlarged pelvic lymph nodes were identified, but a small amount of pelvic effusion was present (Fig.  1 ). The patient was initially admitted to the general surgery department. She continued to experience persistent swelling, pain, and tenderness in the right lower quadrant, accompanied by a low-grade fever. She reported constipation for three days with minimal passage of flatus but normal urination. The patient denied urinary frequency or urgency, abnormal vaginal discharge, and recent sexual activity. She reported no history of diarrhea or previous episodes of similar abdominal pain. Additionally, the patient had no history of prior medical examinations, abdominal discomfort, significant medical or surgical illnesses, or relevant family history. Fig. 1 A , B Abdominal CT image of the cyst shown by the blue arrow, green arrow points to uterus Given the location and nature of the mass, a gynaecological consultation was requested. Gynaecological examination revealed the following: vulva consistent with parous status; smooth vaginal walls; cervix of moderate erosion with positive cervical motion tenderness (‘lifting pain’); uterus in median position, with a soft mass approximately 20 cm in diameter palpable anteriorly; significant lower abdominal tenderness; and bilateral adnexal tenderness (+/-). The patient had a regular menstrual cycle. She denied any sexual activity within the past year. Considering the clinical presentation (acute pain, fever, palpable mass, cervical motion tenderness, elevated inflammatory markers) and imaging findings, the possibility of ovarian cyst torsion was considered the most likely diagnosis, despite the initial CT report not definitively identifying an ovarian origin.Consequently, the patient was transferred to the gynaecology department on the same night for emergency surgical intervention. Preoperative laboratory tests revealed negative HCG, HGB at 113 g/L, cancer Antigen 125 (CA125) at 243 U/mL (elevated; normal range typically < 35 U/mL), and D-dimer 4.36 µg/mL (elevated; normal range typically < 0.5 µg/mL). The coagulation profile was otherwise unremarkable. Emergency laparoscopic exploration was performed. A large cystic mass was visualized, extending from below the umbilicus deep into the pelvic cavity. The mass was found to originate from the greater omentum near the ascending colon region and exhibited dense inflammatory adhesions to the pelvic sidewall. After meticulous separation of these adhesions, the cyst was measured to be approximately 25 × 15 × 15 cm in size. It was multilocular, with the largest locule approximately 10 cm in diameter, and was filled with dark blood and brownish-yellow fluid, indicative of hemorrhage. Careful inspection confirmed that the uterus and both adnexa (ovaries and fallopian tubes) were entirely normal in appearance. The intestinal tract also showed no abnormalities, and there was no sign of invasion into surrounding tissues (Fig.  2 ). The omental cyst was completely excised without complications. Fig. 2 Laparoscopic intraoperative findings. A : The inferior cyst was exposed after separation of the omentum. B : Exploration of the uterine adnexa after removal of the omental mass revealed no abnormalities Postoperative pathological examination of the excised abdominal mass revealed cyst wall-like fragmented tissue measuring 115 × 110 × 20 mm overall. The cyst wall thickness ranged from 2 to 4 mm, with a smooth inner surface and evidence of hemorrhage. Microscopic examination revealed fibrous adipose tissue and vascular structures forming the cyst wall, which were partially lined by mesothelial cells. Extensive hemorrhage was noted within the cyst wall, along with areas of necrosis and significant inflammatory cell infiltration. The final pathological diagnosis was benign omental cyst with hemorrhage and necrosis. Immunohistochemistry revealed positive staining for AE1/AE3, SMA, and calretinin, with low Ki-67 expression (< 1%), supporting a benign mesothelium-lined cyst (Fig.  3 ). Fig. 3 Pathology and immunohistochemistry of omental cysts. A : HE staining (100 ×) microscopic field of omental cyst; C : calretinin (mesothelial +), (100 ×) microscopic field A , B Abdominal CT image of the cyst shown by the blue arrow, green arrow points to uterus Laparoscopic intraoperative findings. A : The inferior cyst was exposed after separation of the omentum. B : Exploration of the uterine adnexa after removal of the omental mass revealed no abnormalities Pathology and immunohistochemistry of omental cysts. A : HE staining (100 ×) microscopic field of omental cyst; C : calretinin (mesothelial +), (100 ×) microscopic field The patient recovered well and was discharged three days postoperatively. No recurrence was observed at the 11-month follow-up.