An appendiceal neurofibroma(ANF) is a rare neoplasm associated with neurofibromatosis type 1(NF-1),an inheritable neurocutaneous disorder that involves multiple systems including the intraabdominal organs.Appendiceal diverticulitis occasionally ruptures in the absence of intense abdominal pain,which can lead to serious consequences.Recent reports highlight the association between appendiceal diverticulum and appendiceal neoplasms; however,there is still little information on the association between appendiceal diverticulitis and ANF in NF-1.A 51-year-old Japanese male with NF-1 was referred to the division of surgery for mild right lower quadrant pain.It was suspected he had perforated acute appendicitis with periappendiceal abscess based on clinical manifestations and findings of computed tomography.An emergency appendectomy was conducted.The pathological examination revealed diffusely proliferated tumor cells of a neurofibroma,coexistent with multiple appendiceal diverticulums,leading to the diagnosis ofperforated appendiceal diverticulitis associated with ANF.Although he developed a remnant abscess,he recovered with the conservative treatments of antibiotics and drainage.This case suggests that appendiceal diverticulitis might be a complication of appendiceal involvement of NF-1,and that it occasionally ruptures in the absence of intense abdominal pain.Clinicians should recognize that NF-1 can cause various abdominal manifestations. An appendiceal neurofibroma (ANF) is a rare neoplasm associated with neurofibromatosis type 1 (NF-1), an inheritable neurocutaneous disorder that involves multiple systems including the intraabdominal organs. Appendiceal diverticulitis occasionally ruptures in the absence of intense abdominal pain, which can lead to serious consequences. Reports highlight the association between appendiceal diverticulum and appendiceal neoplasms; however, there is still little information on the association between appendiceal diverticulitis and ANF in NF-1.A 51-year-old Japanese male with NF-1 was referred to the division of surgery for mild right lower quadrant pain. It was suspected he had perforated acute appendicitis with periappendiceal abscess based on clinical manifestations and findings of computed tomography. Ann emergency appendectomy was conducted. pathological examination revealed diffusely proliferated tumor cells of a neurofibroma, coexistent with multiple appendiceal diverticulums, leadin g to the diagnosis of perforated appendiceal diverticulitis associated with ANF. Although he developed a remnant abscess, he recovered with the conservative treatments of antibiotics and drainage. This case suggests that appendiceal diverticulitis might be a complication of appendiceal involvement of NF-1, and that it occasionally ruptures in the absence of intense abdominal pain. Clinicians should recognize that NF-1 can cause various abdominal manifestations.