Contributed by Alicia Hunt, MD and Alyssa Krasinskas, MD
The patient is a 52-year-old male who presented to gastroenterology with a 3 week history of abdominal pain. He described the abdominal pain as sharp, mid upper abdominal pain that occurred immediately after meals and was not relieved by over-the-counter antacids or pain medications. He had some heartburn, but denied other gastrointestinal symptoms. A colonoscopy was performed and showed a large intraluminal mass in the proximal ascending colon. A biopsy was performed but was not representative of the mass. A right hemicolectomy was performed.
A 7 x 5.5 x 4.5 cm exophytic, polypoid, round mass with a rough, brown surface was attached to the mucosal surface by a short stalk (1.5 x 1.2 cm) (Fig. 1). The cut surface of the mass was cream to white and firm with areas of hemorrhage and ulceration. The submucosa appeared to be pulled into the stalk of the mass (Fig. 2). The overlying colonic mucosa was nearly completely denuded.
HISTOLOGICAL AND IMMUNOHISTOCHEMICAL FINDINGS
Microscopically, the mass was composed of spindle cells with abundant eosinophilic cytoplasm and mild nuclear pleomorphism (Figs. 3 and 4). There were 1-2 mitoses/10 high powered fields. In areas, the cells exhibited a streaming or fascicular pattern and some areas contained a myxoid background. The tumor cells were positive for smooth muscle actin (Fig. 5) with rare cells positive for caldesmon and desmin, and negative for C-KIT (CD117) and DOG-1. Lymph nodes were negative for metastatic disease.