Peritoneal Inclusion Cyst Mimicking Adrenal Pathology in a Young Man: A Rare Case Report.

Peritoneal inclusion cysts (PICs) are rare, benign, and fluid-filled lesions most commonly seen in women of reproductive age, typically associated with a history of abdominal surgery, trauma, or inflammatory conditions. Occurrence in males, especially without predisposing factors, is exceedingly uncommon and can pose significant diagnostic challenges due to their nonspecific clinical and radiological features. We report the case of a 19-year-old male who presented with chronic right lower quadrant abdominal pain persisting for 4 months. Initial sonography revealed an 80 × 50 mm cystic lesion between the liver and kidney, with subsequent imaging-including contrast-enhanced computed tomography and magnetic resonance imaging-suggesting an adrenal cyst. Functional and serological workups for adrenal and hydatid pathology were negative. Due to the lesion's size and persistent symptoms, surgical excision was performed. Intraoperatively, the cyst was found in the retroperitoneal space adjacent to, but not adherent to, the adrenal gland. Histopathological and immunohistochemical analyses confirmed the diagnosis of a PIC. The patient's postoperative recovery was uneventful. This case illustrates the diagnostic complexity of PICs in atypical patient populations. The lesion's radiological resemblance to adrenal or other retroperitoneal cystic masses led to initial misdiagnosis and extensive workup. Literature review reveals very few similar cases in males without prior surgery or inflammation. PICs should be considered in the differential diagnosis of cystic abdominal lesions, even in young males without typical risk factors. Accurate diagnosis relies on a combination of clinical assessment, imaging, and histopathological evaluation to ensure appropriate management.