Abstract
INTRODUCTION: A gastrointestinal stromal tumor (GIST) with an elevated serum tumor marker level is very rare. We report a case of jejunal GIST associated with extremely elevated levels of serum carbohydrate antigen 19-9 (CA19-9). PRESENTATION OF CASE: A 61-year-old woman was referred to our hospital for examination of an abdominal tumor. Laboratory tests revealed extremely elevated CA19-9 levels (13,498 U/mL). Enhanced abdominal computed tomography demonstrated a well-enhanced, round 40 mm tumor. The patient underwent a jejunectomy and lymph node dissection. Based on the postoperative pathological findings, the tumor was diagnosed as a GIST. Microscopically, a solid region of the resected tumor showed negative staining for CA19-9. The serum CA19-9 level drastically decreased postoperatively. DISCUSSION: Increased proliferation of epithelial cells secondary to inflammation and ulceration of epithelia may lead to increased secretion and accumulation of CA19-9, which is consequently released into the blood circulation. CONCLUSION: In cases of GIST, an isolated increase of serum CA19-9 is extremely rare; but they are not necessarily associated with malignant transformation.