Reactive nodular fibrous pseudotumor of the omentum: a rare case report and literature review

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BACKGROUND: Reactive nodular fibrous pseudotumor is a rare benign fibroinflammatory lesion of the gastrointestinal tract and mesentery that can closely mimic malignant disease on clinical examination and imaging. Most reported cases are associated with prior abdominal surgery, trauma, or inflammation. Omental involvement is particularly uncommon, and preoperative diagnosis remains difficult because of its rarity and the limited description of multimodality imaging findings. We report a rare case of omental reactive nodular fibrous pseudotumor in a young man without any history of abdominal surgery, trauma, or abdominal discomfort, highlighting its unusual presentation and diagnostic features. CASE PRESENTATION: A 31-year-old man presented with a palpable abdominal mass that had been present for more than 1 month. He had no previous abdominal surgery, trauma, or gastrointestinal symptoms. Contrast-enhanced computed tomography revealed multiple well-defined solid masses in the greater omentum with scattered calcifications. The lesions were similar in attenuation to skeletal muscle on unenhanced images and showed mild progressive enhancement after contrast administration. Magnetic resonance imaging demonstrated low signal intensity on both T1-weighted and T2-weighted images with a similar gradual enhancement pattern. Ultrasound and contrast-enhanced ultrasound showed hypoechoic lesions with limited enhancement. Because malignancy could not be excluded radiologically, surgical resection was performed. Histopathological examination demonstrated spindle cell proliferation within dense hyalinized collagenous stroma with focal chronic inflammatory infiltrates. Immunohistochemical findings supported the diagnosis of reactive nodular fibrous pseudotumor. The patient recovered well after surgery and remained recurrence-free during more than 4 years of follow-up. CONCLUSIONS: This case indicates that reactive nodular fibrous pseudotumor should be included in the differential diagnosis of solid omental masses, even in patients without a history of abdominal surgery or inflammation. Multimodality imaging may provide important clues to its fibrous nature, but definitive diagnosis still depends on histopathological confirmation. Greater awareness of this rare entity may reduce misdiagnosis and help avoid unnecessary aggressive treatment.

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