A Resected Pseudomyogenic Hemangioendothelioma and Epithelioid Hemangioendothelioma Metachronously Derived from the Greater Omentum

A 78-year-old man was referred to our hospital in 2017 for a curative operation for gastric cancer after treatment of endoscopic submucosal dissection. We performed proximal gastrectomy and recognized tumors (5–20 mm in size) at the greater omentum. We resected the tumors with the greater omentum. The tumors were pathologically diagnosed as epithelioid hemangioendothelioma. Because he had previously undergone a resection of an abdominal tumor in our hospital in 2013, we retrospectively reviewed the series of imaging and the surgical and pathological findings of this tumor to evaluate the relation to the tumors resected in 2017. According to the operation records and the imaging in 2013, this tumor was about 10 cm in diameter, and located solitarily near the middle of the major curvature of the stomach, but there was no direct communications with the left lobe of liver, the stomach, or the transverse colon. We suspected that this tumor in 2013 was derived from the greater omentum, too. We examined the immuno‐ histochemical staining of this tumor, and finally diagnosed it as pseudomyogenic hemangioendothelioma, which was different from the tumors resected in 2017. It is extremely rare that the different types of hemangioendothelioma (pseudomyogenic hemangioendothelioma and epithelioid hemangioendothelioma) occurred at the greater omentum metachronously.