when a mass is palpable or detected incidentally by imaging studies in the lower right abdomen in a patient without a history of appendectomy , the possibility of appendiceal mucocele ( am ) needs to be considered . am is a descriptive term for mucinous distension of the appendiceal lumen regardless of the underlying pathology . four causal pathologic conditions have been reported : retention cyst , mucosal hyperplasia , cystadenoma ( or mucinous tumor of unknown malignant potential ) and cystadenocarcinoma . in cystadenomas , the most common form , luminal dilatation can reach up to 6 cm and is associated with appendiceal perforation in 20% of cases , resulting in mucinous spillage into the periappendicular area and peritoneal cavity . histological examination of the mucus does not reveal any neoplastic cells , and appendectomy is usually curative . although underlying malignancies in a mucocele are important for the management , preoperative diagnosis of the etiology of am is difficult on imaging studies . am can present in a variety of clinical conditions , but concomitant ulcerative colitis ( uc ) is extremely rare . a 33-year - old female patient with uc was referred to our outpatient clinic in january 2003 . mesalazine was started orally , and the disease was in remission by may 2003 . since then , she was followed regularly in our department . in january 2008 , she was referred again to our outpatient clinic with right lower abdominal pain without bloody diarrhea . colonoscopy revealed mild proctosigmoiditis and a submucosal tumor with a maximum diameter of 5 cm in the cecum ( fig . as the cecum was occupied by the large tumor , the orifice of the vermiform appendix was observed like a volcano . endoscopic biopsy failed to give histological diagnosis . computed tomography ( ct ) revealed a large , hypodense , cystic tube - like structure extending into the pelvic space ( fig . an abdominal sonography revealed peculiar onion - skin - like internal echogenicity in the right lower abdomen ( fig . since the dull pain was severe , informed consent was obtained and partial resection of the cecum including the tumor was performed in march 2008 . intraoperatively , the vermiform appendix was swollen like a sausage and compressing the cecum , which accounted for what appeared to be a submucosal tumor simulating a volcano by endoscopy . the vermiform appendix was spindle - shaped , measured 12 cm in length and 3 cm in diameter ( fig . 4 ) and was filled with a large quantity of viscous liquid ( fig . 5 ) . postoperative pathological diagnosis was cystadenoma , and no cancer cells were present in the viscous liquid within or the vermiform appendix or its wall . the patient left the hospital 7 days postoperatively , and her colitis has been in remission without any complication . am is a rare pathology of the appendix characterized by a cystic dilatation of the lumen with stasis of mucus . its incidence ranges between 0.2 and 0.3% of all appendectomies , with a higher frequency in females and in patients more than 50 years of age . symptoms of am are nonspecific , but even large lesions up to 4 cm are symptomatic in 75% of patients . the most common presentation is right lower quadrant pain , similar to acute appendicitis ; a palpable mass can be found in 50% of cases , whereas urinary dysfunction or hematuria is rarely associated . the diagnosis is difficult on preoperative imaging studies ; up to 60% are diagnosed during operations for other conditions . variable significance of ultrasonography and ct have been reported [ 5 , 9 , 10 ] : ultrasonography can show an elongated hypoechoic mass that is not typical of a cyst . fine echo spots and/or concentric echogenic layers within the cystic mass , so - called onion skin , are thought to be specific signs for am . small lymph nodes or soft tissue in the surrounding fat on ct may suggest the possibility of malignancy . in our patient , as she had been under treatment of uc for more than 5 years , am was detected in the right lower abdomen for severe dull pain . the question arises whether there is a direct link between inflammatory bowel disease ( such as uc ) and am . some authors have suggested that the vermiform appendix or the appendiceal orifice might be involved in uc . although the relation between am and uc still remains unclear , inflammation in the cecum may facilitate obstruction of the appendiceal lumen as suspected in our patient .
a 33-year - old female patient with ulcerative colitis was referred to our outpatient clinic in january 2008 with right lower abdominal pain without bloody diarrhea . 
 colonoscopy found mild proctosigmoiditis and a submucoal tumor with a maximal diameter of 5 cm in the cecum . computed tomography revealed a large , hypodense , cystic cylindrical structure extending to the pelvic space . for severe pain , she underwent partial resection of the cecum including the tumor in march 2008 . 
 intraoperatively , the vermiform appendix was swollen like a sausage and compressing the cecum , which accounted for what appeared to be a submucosal tumor like a volcano by endoscopy . 
 lymphadenectomy was not performed because malignancy was not suspected . in the surgical specimen , 
 the vermiform appendix was spindle - shaped and contained a large quantity of viscous liquid . 
 postoperative pathological diagnosis was mucinous cystadenoma , and no cancer cells were present in the viscous liquid within the vermiform appendix . 
 the patient left the hospital 7 days postoperatively , and her colitis remains in remission without any complications .