Image of the Month—Diagnosis

A 33-year-old man with a significant history for ruptured appendicitis, for which he underwent an open appendectomy 2 years previously, described a slowly progressing fullness in the right lower quadrant since surgery. He was found to have a large solid mass in the mid right abdomen, which on examination extended from the right upper quadrant down to the pelvis. The mass was mobile and mildly tender on palpation. The patient denied any other signs or symptoms. Abdominal computed tomography was performed (Figure 1and Figure 2).

Figure 1. 

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Abdominal computed tomographic scan showing a well-circumscribed, 13 × 18-cm mass with central necrosis in the right lower quadrant.

Figure 2. 

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Abdominal computed tomographic scan showing the heterogeneous mass.

A. Carcinoid tumor of the appendix

B. Retroperitoneal sarcoma

C. Mucinous adenocarcinoma of the appendix

D. Cecal gastrointestinal stromal tumor