Secret in a castle (man): A rare diagnostic surprise – A case report on a unicentric form of Castleman disease in a young adult male

Castleman disease (CD) is a rare lymphoproliferative disorder classified into unicentric and multicentric forms, with unicentric disease typically presenting as a localized and benign condition that can be difficult to diagnose due to non-specific clinical and radiological findings. We report a 20-year-old male with an incidentally detected mesenteric mass on imaging for acute gastroenteritis. Serial imaging showed interval growth, and the patient underwent surgical excision. Intraoperatively, a well-encapsulated jejunal mesenteric mass was identified and completely removed. Histopathology revealed features characteristic of the hyaline vascular variant of unicentric CD (UCD). The post-operative course was uneventful, and the patient remains well on follow-up. UCD can mimic other mesenteric tumors, and definitive diagnosis relies on histopathological evaluation. Complete surgical excision is both diagnostic and curative, with an excellent prognosis. It should be considered in the differential diagnosis of solitary mesenteric masses in young adults.