50-year-female presented to us with awareness of lump in right iliac fossa (RIF) for 3 months, gradually increasing in size with dull aching pain. On examination there was a lump in the RIF region arising from pelvis, it was 12 × 6 cm in On investigations routiene test were with in normal limits CA 125 level was 8.12 U/ml. Patient underwent radiological imaging and USG and CT were suggestive of adnexal mass (Fig. 1) , on laparotomy 13 × 6 cm cystic mass found replacing the appendix, both the adnexa were normal (Fig. 2). Histology was suggestive of benign mucocele of appendix. DiscussionMucocele of the appendix is a relatively uncommon pathology with a reported incidence of 0.2-0.3% in all appendectomy specimens [1].Two major pathological mechanisms are thought to be responsible for the formation of apendiceal mucocele; -plasia, or appendiceal lesions (e.g., fecaliths, endometriosis, diverticulae, polyps) and second tumors of the appendix (i.e., carcinoid, cystadenoma, cystadenocarcinoma). IMAGES IN SURGERY