Serosal appendicitis: incidence, causes and clinical significance

BACKGROUND: Serosal appendicitis is a histopathological diagnosis of an inflammatory reaction on the surface of the appendix caused by an extra appendiceal source of inflammation. OBJECTIVE AND METHODS: A retrospective review of a pathology database in a district general hospital identified patients with serosal appendicitis and a preoperative diagnosis of appendicitis. Two groups emerged: patients with serosal appendicitis secondary to a known cause of intra-abdominal inflammation and those in whom the cause remained unknown. The groups were compared with respect to postoperative complications, referral to outpatient clinics, admissions and procedures by case-note analysis. RESULTS: The incidence of serosal appendicitis was 0.01% (19/1379); 17 women; mean age 31.63 (10.49) years. Lanz incision was used in 16 patients, midline laparotomy in two and laparoscopy in one. A preoperative ultrasound scan was carried out in 5 of 19 patients. The cause of serosal appendicitis was confirmed in eight patients (intraoperatively or postoperatively) and remained unknown in 11 patients. The groups were comparable with respect to age, sex and mean follow-up. No significant difference was observed between them with respect to the above parameters. CONCLUSIONS: No further investigation is necessary in patients who undergo an appendicectomy but in whom the pathological diagnosis is serosal appendicitis. However, considering the patient demographics and the fact that patients with serosal appendicitis have probably undergone an unnecessary appendicectomy, the proportion of patients who underwent ultrasound scanning and diagnostic laparoscopy was small.