Distinctive histopathologic findings of pancreatic hamartomas suggesting their 'hamartomatous' nature: A study of 9 cases

Hiroshi Yamaguchi, Shinichi Aishima, Yoshinao Oda, Hiroki Mizukami, Takuma Tajiri, Sohsuke Yamada, Takashi Tasaki, Keisuke Yamakita, Koji Imai, Fumi Kawakami, Shigeo Hara, Keiji Hanada, Tomohiro Iiboshi, Toshikatsu Fukuda, Hiroshi Imai, Hiroyuki Inoue, Tatsuya Nagakawa, Shunji Muraoka, Toru Furukawa, Michio Shimizu

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26 Citations (Scopus)


Pancreatic hamartoma is a rare tumor, and its characteristic histopathologic features have not yet been fully evaluated. In this study, we collected 9 cases of pancreatic hamartoma to elucidate distinctive histopathologic features that can serve to establish this tumor as a clear disease entity and thus formulate useful histopathologic criteria for this tumor. The cases comprised 4 men and 5 women with a mean age of 62.7 years. The average tumor diameter was 3.3 cm. All patients underwent surgical treatment, and none showed any recurrence postoperatively. Macroscopically, pancreatic hamartomas were well-demarcated tumors with a solid or solid and cystic appearance. Microscopically, these tumors comprised mature acini and small-sized to medium-sized ducts showing a distorted architecture with various amounts of fibrous stroma. Strikingly, the tumors consistently lacked concentric elastic fibers in their duct walls, peripheral nerves, and well-formed islets of Langerhans, all of which exist in both the normal and atrophic pancreas. Immunohistochemically, scattered chromogranin A-positive neuroendocrine cells were observed in the acinar and ductal components. Ductal components were positive for S-100 protein. Spindle-shaped stromal cells expressed CD34 and/or c-kit. These histopathologic features were distinct from those of 5 cases of pancreatic ductal adenocarcinoma, 3 cases of type 1 autoimmune pancreatitis (lymphoplasmacytic sclerosing pancreatitis), 3 cases of alcoholic chronic pancreatitis, and 5 cases of normal pancreas. In conclusion, pancreatic hamartomas share some distinctive histopathologic features and clinical outcomes (neither recurrence nor metastasis) that allow them to be interpreted as malformative lesions. The term 'hamartoma' is appropriate for these unique lesions.

Original languageEnglish
Pages (from-to)1006-1013
Number of pages8
JournalAmerican Journal of Surgical Pathology
Issue number7
Publication statusPublished - Jul 2013

All Science Journal Classification (ASJC) codes

  • Anatomy
  • Surgery
  • Pathology and Forensic Medicine


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