Giant appendiceal mucocele mimicking gastrointestinal stromal tumor of the cecum

A 54-year-old man presented with chronic abdominal pain and chronic diarrhea. He underwent a routine endoscopic examination. Colonoscopy demonstrated a huge submucosal tumor measuring 4.2 × 4.0 × 5.0 cm at the cecum ([Fig. 1]). Endoscopic ultrasonography (EUS) using a miniprobe revealed a 4-cm well-circumscribed, hypoechoic, homogeneous lesion arising from the fourth sonographic layer ([Fig. 2]), and the lesion was diagnosed as a large gastrointestinal stromal tumor (GIST) of the cecum. CT scan of the lower abdomen showed a cystic lesion compressing the cecum ([Fig. 3]). The patient underwent an exploratory laparotomy and the intraoperative finding was of a giant appendiceal mass ([Fig. 4]). Right hemicolectomy was performed and the pathological analysis confirmed a mucinous tumor of borderline malignancy with free surgical margins. The patient recovered well without any postoperative complications.

Fig. 1 Colonoscopy revealed large submucosal mass covered with normal colonic mucosa.

Fig. 2 Endoscopic ultrasonography demonstrated a 4-cm well-circumscribed, hypoechoic, homogeneous lesion compressing the cecal wall.

Fig. 3 CT scan of the lower abdomen demonstrated a round, low-density, thin-walled, encapsulated mass at the cecum (arrow), about 5 cm in diameter.

Fig. 4 Intraoperative photograph showing a large appendiceal mass.

Patients with appendiceal mucocele usually manifest a variety of symptoms, but they can also be asymptomatic. Right lower quadrant pain is the most common symptom, occurring in 64 % of patients [1]. Accurate preoperative diagnosis is rare, but it is possible using appropriate investigations. Endoscopically, this lesion appears as a submucosal mound with normal mucosa in the cecum. The classical appearance is of a “volcano sign” with the appendiceal orifice visible at the center of the mound [2] [3]. The EUS finding was first described by using an ultrasonic probe to rule out colonic submucosal tumors such as carcinoids or lipoma prior to surgery [4] [5]. Right hemicolectomy is a standard treatment and gives an excellent prognosis for these lesions. This case exemplifies the challenge of detection and the management of an appendiceal mucocele presenting as a large GIST of the cecum.

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References

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