REVIEW ARTICLE Malignant Appendiceal GIST: Case Report and Review of the Literature Ram Elazary & Avraham Schlager & Abed Khalaileh & Liat Appelbaum & Miklosh Bala & Mahmoud Abu-Gazala & Areej Khatib & Tzahi Neuman & Avraham I Rivkind & Gidon Almogy Published online: 4 December 2009 # Humana Press Inc. 2009 Abstract Introduction Gastro-intestinal stromal tumors (GISTs) of the appendix are a rare entity. To date, only a handful has been described in the literature, all of which have been of the benign type. Case Report We present the first reported case of a malignant appendiceal GIST. The tumor was discovered when the patient presented with a peri-appendiceal abscess which appeared suspicious on CT. The abscess was drained and managed medically. The patient responded to antibiotic treatment but subsequent CT and biopsy confirmed the diagnosis of appendiceal GIST, and the patient was started on treatment with imatinab mesylate. Discussion One week after initiation of therapy, the patient returned with frank peritonitis necessitating surgery. Ab- dominal exploration revealed an appendiceal GIST locally invading and perforating adjacent bowel. We describe the complex presentation and course of the case as well as a literature review of the appendiceal GISTs and the current approach to treatment. Keywords gastrointestinal stromal tumor . appendix . imatinib mesylate . c-kit Introduction Gastrointestinal stromal tumors (GISTs) are the most common primary mesenchymal tumor of the gastrointestinal (GI) tract. Although the vast majority occur in the stomach, GISTs have been described throughout the GI tract and, more recently, even in mesenchymal structures outside the GI tract [1]. There are fewer than ten reported cases of appendiceal GIST in the literature, all of which were benign according to both pathologic and clinical standards. This finding has led some authors to suggest that appendiceal GISTs may be an indolent and more benign subset of GIST tumors [2]. We present the first reported case of malignant appendiceal gastrointestinal stromal tumor as well as a review of the literature on the appendiceal GISTs and the current approach treatment. Case Report A 57-year-old male presented at the emergency department complaining of severe, diffuse abdominal pain which began 2 days prior. He reported that the pain was progressive in nature but unaccompanied nausea or vomiting. The patient's medical history was significant for hypertension and non- insulin dependent diabetes. On physical exam, he was afebrile with normal vital signs. His abdomen was soft with moderate tenderness and distension, but no signs of guarding or rebound. Computed tomography (CT) scan of the abdomen and pelvis demonstrated a thick-walled appendix with a surrounding 10 cm fluid collection and an air-fluid level consistent with a peri-appendicular abscess. Additionally, a lobulated, heterogeneous, soft tissue mass with multiple tiny pockets of fluid was noted at the caudal aspect of the abscess which could not be clearly identified. The patient underwent A. Schlager (*) New York University Hospital, New York, USA e-mail: avi.schlager@gmail.com R. Elazary : A. Schlager : A. Khalaileh : L. Appelbaum : M. Bala : M. Abu-Gazala : A. Khatib : T. Neuman : A. I. Rivkind : G. Almogy Hadassah-Hebrew University Medical Center, Jerusalem, Israel J Gastrointest Canc (2010) 41:9–12 DOI 10.1007/s12029-009-9113-8