Mesoappendiceal and periappendiceal lesions.

Lesions of the mesoappendix are rare. The majority are benign and incidental pathologic findings. They rarely present clinically or radiologically. A spectrum of infectious, tumor-like, and neoplastic lesions can involve the mesoappendix and the periappendiceal tissue. Pathologists usually pay little attention to the gross examination of the mesoappendix in appendectomy specimens in comparison to the appendix itself. This could lead to a missed opportunity to identify mesoappendiceal lesions, despite being rare, but some are clinically important for the patient's management. Pathologists should perform careful gross examination and sectioning of the mesoappendix. A retrospective review study of 4371 appendectomy specimens over four years showed eight cases (0.18%) with a variety of mesoappendiceal and periappendiceal lesions. Most (five cases) were benign incidental pathologic findings (lymph nodes with reactive follicular hyperplasia, ectopic decidua, infarcted epiploica and peritoneal cyst), one case was a rare occurrence (inflammatory fibroid tumor), and few others (two cases) were clinically important findings (tuberculosis and schistosomiasis). They were more commonly found in young adult males with a male to female ratio of 7:1.