Case Report: subhepatic appendicitis complicated by hepatic abscess as the initial presentation of primary diffuse large B-cell lymphoma of the appendix: first reported case.

Subhepatic appendicitis complicated by hepatic abscess is an uncommon clinical condition due to anatomical variations in the appendix's position. Here, we report an unusual case of a 56-year-old male who initially presented with right abdominal pain and fever, misdiagnosed as bilateral kidney stones and urinary tract infection. Subsequent abdominal CT(Computed Tomography) scans revealed subhepatic appendicitis with a hepatic abscess located in segment VI of the liver. The patient underwent successful laparoscopic appendectomy and hepatic abscess drainage. Unexpectedly, histopathological examination of the appendix demonstrated diffuse large B-cell lymphoma (DLBCL), a rare form of primary appendiceal non-Hodgkin lymphoma. Immunohistochemistry confirmed the diagnosis, with tumor cells positive for CD20, CD79a, Bcl-6, and c-Myc, and a high Ki-67 proliferative index (>90%). This case highlights the diagnostic challenges associated with atypically positioned appendicitis and underscores the importance of pathological evaluation in detecting rare underlying malignancies.