A Minute Nonfunctioning Pancreatic Endocrine Tumor with Ductal Structures and Prominent Fibrous Stroma: Report of a Case

Naoki Ikenaga¹⁾, Kazuyoshi Nishihara¹⁾, Fujio Katsumoto¹⁾, Hiroaki Matsunaga¹⁾, Toshihumi Nasu²⁾, Yumi Oshiro⁵⁾, Mari Nakamori³⁾, Satoshi Toyoshima³⁾, Minoru Ono⁴⁾ and Shoshu Mitsuyama

Department of Surgery¹⁾, Department of Internal Medicine²⁾, Department of Pathology³⁾ and Department of Radiology⁴⁾, Kitakyushu Municipal Medical Center
Department of Pathology, Matsuyama Red Cross Hospital⁵⁾

A 50-year-woman reporting general fatigue and found in abdominal ultrasonography to have a 1 cmtumor in the body of the pancreas was suspected of pancreatic endocrine tumor because of contrast medium enhanced in CT. Abdominal MRI showed a low-intensity mass in the pancreatic body both in T1 and T2-weighted imaging unusual for an endocrine tumor. Serum CA19-9 was markedly elevated at 1,459.2 U/ml, necessitating resection because pancreatic ductal carcinoma could not be ruled out. Histologically, the well-circumscribed tumor consisted of nests of endocrine tumor cells embedded in prominent fibrous stroma. The strong fibrosis appeared to cause the low intensity in T2-weighted MRI. The tumor had focally evident ductal structures and close contact with endocrine tumor cells. Immunohistologically, tumor cells were positive for chromogranin A and glucagon, but were negative for insulin, gastrin, and somatostatin. The ductal component was immunoreactive to CA19-9. The tumor was definitively diagnosed as nonfunctioning pancreatic endocrine tumor. Pathological findings in this case support the idea of pancreatic duct epithelia were differentiating into endocrine cells and ductal structures.

Key words
endocrine tumor, ductal structure, nonfunctioning

Reprint requests
Naoki Ikenaga Department of Surgery, Kitakyushu Municipal Medical Center
2-1-1 Bashaku, Kokurakita-ku, Kitakyushu, 802-0077 JAPAN

Accepted
December 17, 2004

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