Mucinous cystadenoma of the appendix in a patient with systemic lupus erythematosus.

A 38-year-old female with systemic lupus erythematosus presented with abdominal pain, diarrhea and iron-deficient anemia. Computed tomogram showed a 2 x 4 cm inhomogeneous lesion of the right adnexa. An unusual mass was identified extending from the appendiceal orifice at colonoscopy, and an 8 cm tubular appendix, apparently prolapsed into the cecum, was identified at celiotomy. An appendectomy with cecectomy was performed. On cut section, mucin was extruded from the lumen of the appendix. A mucinous neoplasm of the appendix with mucinous dissection to the serosal surface was reported at the time of frozen section. No gross ovarian pathology or peritoneal implants were noted. Cystadenoma with associated mucocele formation was verified by permanent histology. Mucocele of the vermiform appendix is a rare condition associated with neoplastic transformation in approximately 75% of all cases. Benign mucinous cystadenoma of the appendix should be differentiated from cystadenocarcinoma by frozen section at the time of celiotomy to ensure appropriate treatment. While systemic lupus erythematosus can lead to cutaneous mucinosis, an association with mucinous cystadenoma of the appendix has not been previously reported. Surveillance for metachronous colonic neoplasms is warranted in patients diagnosed with a mucinous neoplasm of the appendix.