A Case of Myoepithelial Hamartoma: Morphological Variation Supported by OCT4 Expression

Abstract

In this report, we describe a patient with myoepithelial hamartoma, which is regarded as synonymous with adenomyosis and heterotopic pancreas. Endoscopy revealed a submucosal tumor in the antrum of the stomach. Subsequently, distal gastrectomy with Roux-en-Y reconstruction was performed. Histological findings of adenomyomatous lesion and heterotopic pancreatic tissue were observed in this lesion. The distribution of OCT4, which is a pluripotency marker, varied in each part.

Nonpolypous Hamartomas of the Gastrointestinal Tract: An Updated Review on Classification, Denominations, and Clinical Management

“…This hamartoma, which is also known as adenomyosis or ademyomata, is a variant of Heinrich's type 2 ectopic pancreas which appears as a submucosal mass of the GI tract [ 11 , 55 – 58 ]. As it is especially located in the gastric antrum (85%) and pylorus (15%), Magnus-Alsleben called it in 1903 “adenoma of the pylorus” [ 56 ] being later called adenomyoma [ 57 ].…”

“…As it is especially located in the gastric antrum (85%) and pylorus (15%), Magnus-Alsleben called it in 1903 “adenoma of the pylorus” [ 56 ] being later called adenomyoma [ 57 ]. Only 58 cases were reported till 2019 in the stomach and 7 cases in the ampulla of Vater [ 11 , 57 , 59 ]. Under microscope, it is composed by smooth muscle bands admixed with glandular structures, some of them cystically dilated, Brunner or pyloric glands, and trypsin-positive pancreatic acini [ 11 , 57 ].…”

“…Only 58 cases were reported till 2019 in the stomach and 7 cases in the ampulla of Vater [ 11 , 57 , 59 ]. Under microscope, it is composed by smooth muscle bands admixed with glandular structures, some of them cystically dilated, Brunner or pyloric glands, and trypsin-positive pancreatic acini [ 11 , 57 ]. It can coexist with other malformations such annular pancreas, gastric duplication, and duodenal adenomas [ 57 ].…”

“…The two main groups of GI hamartomas are the hamartomatous familial gastrointestinal polyposis [ 5 ] and vascular hamartomas [ 4 , 6 – 8 ]. The other uncommon subtypes include mesenchymal [ 3 ] and heterotopic hamartomas (e.g., ectopic pancreas or gastric mucosa, gastric duplication, and duplication cysts) [ 9 – 11 ].…”