Endometriosis with peritoneal inclusion cyst: an uncharted territory

Peritoneal inclusion cyst (PIC) are non-neoplastic mesothelium-lined cystic lesions occurring in premenopausal females with functioning ovaries and pelvic adhesions. Endometriosis is one of the common causes for pelvic adhesions and patients may primarily present in the out-patient department with abdominopelvic lump along with complaints of dysmenorrhoea, infertility. On imaging, these PICs appear as unilocular or multilocular thin-walled cystic lesion insinuating and conforming to the shape of adjacent intraperitoneal structures. The ovaries may be entrapped within the cyst giving the spider (spider web pattern -typical of peritoneal inclusion cyst). The imaging appearances of PIC may overlap with various causes of complex adnexal and pelvic cystic lesions including that of ovarian neoplasms, which often require surgical intervention. This makes it imperative to diagnose this entity in the presence of typical imaging characteristics and appropriate clinical setting such as with history of previous pelvic or abdominal surgery, pelvic inflammatory disease, trauma, and endometriosis. We have reported three rare cases of peritoneal inclusion cysts in patients with endometriosis.