First report of connexin 43-positive gastrointestinal stromal tumor (GIST).

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms most frequently found in the stomach and presenting without symptoms or with unspecific ones such as hemorrhage and abdominal pain. The malignant potential of GIST is variable and there are several prognostic indexes for treatment and follow up. The superior diagnostic method is endoscopic ultrasound combined with fine needle aspiration biopsy (EUS-FNA) immunocytochemistry. Surgery is the preferable treatment option, while recurrent or advanced disease is best managed with thyrosine kinase inhibitors. We report a case of a 20-year-old man that presented with gastrointestinal bleeding and anemia. Upper gastrointestinal endoscopy detected a submucosal lesion and computerized tomography revealed a node near the liver. EUS-FNA immunocytochemistry found CD-117 positive cells suggestive of GIST and the patient was operated on. The diagnosis was confirmed by histopathology with immunostaining. Prognostic assessment was done according to tumor size and Ki-67 index with mitosis count on microscopy. Many studies have shown that tumors demonstrate an abnormal number, structure and occurrence of connexin proteins with altered connexin-mediated intercellular communication. Since a great deal of gastroenterological tumors express connexin 43, our aim was to find out whether it was present in GIST. Immunohistochemically, the tumor was positive for connexin 43, which was not previously described as typical. The early postoperative course was uneventful, free from complications. At three-year postoperative follow-up, the patient was subjectively well and without clinical signs of disease recurrence.