PMC4802133_01
Preoperative computed tomography. (a) Engorged inflammatory appendix (b) well-demarcated, enhanced mass (c) cystic lesion.
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On his return visit, computed tomography showed a well-demarcated and enhanced tumor with a cystic component; it appeared to originate from the terminal ileum and measured approximately 2.5 x 6.0 x 2.5 cm (Fig. 1).
Operative findings. C: cecum; TL: terminal ileum; G: solid component of GIST; Cy: cystic component of GIST; AT: appendiceal tip.
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Under laparoscopic exploration (Fig. 2), a solid mass with a cystic component protruded from the proximal appendix and the distal appendix was secondarily engorged.
Cross-sectioned gross findings: a pedunculated tumor attached to the proximal appendiceal muscle wall.
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Appendiceal muscularis propria was present at the root of the tumor; it grossly formed a polypoid outward extension from the proximal appendix (Fig. 3).
(a) Monotonous spindle morphology with irregular fascicles and variably sclerosed stroma (hematoxylin and eosin) (b, c) strong and diffuse expression, respectively, of CD117 and CD34.
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Histologically, the tumor was composed of spindle cells characteristic of GISTs, with irregular fascicles and variably sclerosed stroma (Fig. 4a). Immunohistochemistry showed strong expression of CD117 (Fig. 4b) and CD34 (Fig. 4c) in the tumor cells; however, no reactivity was seen for SMA, desmin, and protein S100.