Objectives: To investigate the frequency of patient characteristics, causative factors and imaging features associated with pathology-proven peritoneal inclusion cysts (PICs).
Methods: From a retrospective search of all available hospital records-dating back 19 years-we identified 228 patients with pathology-proven PICs. Descriptive statistics were calculated for patients' demographic and clinical characteristics. Imaging features of pathology-proven PICs were recorded on a total of 77 computed tomography (CT), magnetic resonance imaging (MRI) and/or ultrasound (US) studies from patients who underwent imaging before surgery.
Results: PICs occurred over a wide age range (18-89 years); 82.5 % of patients were women and 17.5 % were men. A history of prior insult to the peritoneum was identified in 70.6 % of patients. Imaging appearances of PICs ranged from loculated, simple fluid collections to complex, multi-septated lesions. In the absence of haemorrhage or debris, PICs were never found to have thick walls. The presence of nodularity, papillary excrescences or other solid components also excluded a diagnosis of PIC, as did the presence of more than a physiological amount of ascites, provided the ascites had no alternate explanation.
Conclusions: PICs are more common than suggested by previously published reports. Knowledge of patient characteristics and typical PIC imaging appearances may prevent unnecessary or unnecessarily aggressive therapy.