Gastric CLTC-ALK fusion-positive inflammatory myofibroblastic tumor showing an endoscopic superficial depressed-type appearance

• Main Authors: Mai Nakanishi, MD, Jiro Watari, MD, PhD, Toshihiko Tomita, MD, PhD, Yasutaka Nakanishi, MD, Yoshitane Tsukamoto, MD, PhD, Shohei Matsuo, MD, Takashi Uchihashi, MD, Junichi Miyazaki, MD, PhD, Hironori Tanaka, MD, PhD, Shoudou Kojima, MD, PhD, Nobukazu Kuroda, MD, PhD, Ikuo Matsuda, MD, PhD, Hiroto Miwa, MD, PhD, Hisashi Shinohara, MD, PhD, Seiichi Hirota, MD, PhD
• Format: Article
• Language: English
• Published: Elsevier 2019-03-01
• Series: Human Pathology: Case Reports
• Online Access: http://www.sciencedirect.com/science/article/pii/S2214330018301603

We present a 76-year-old Japanese male who had a history of removal of a gastric gastrointestinal stromal tumor (GIST) 6 years ago. Although asymptomatic and having no evidence of recurrence, follow-up endoscopy revealed a small, white depressed lesion of approximately 1 cm with converging mucosal folds in the greater curvature of the fundus, which was suspicious of depressed-type early gastric cancer (GC) by conventional endoscopy. However, no evidence of GC except a “white globe appearance”-like area was identified by magnifying endoscopy with blue laser imaging. The biopsy specimens showed a proliferation of anaplastic lymphoma kinase (ALK)-positive spindle cells in the gastric mucosa, and ALK-rearrangement was detected by fluorescent in situ hybridization. Furthermore, clathrin heavy chain (CLTC)-ALK fusion was seen by genetic analysis, thus the lesion was preoperatively diagnosed as gastric inflammatory myofibroblastic tumor (IMT). For the curative intent, a laparoscopic endoscopic cooperative surgery (LECS) was performed. On the specimens resected by LECS, ALK-positive cells were sporadically distributed in the gastric mucosa and submucosa in the depressed area. In addition, two sporadic GISTs originating from the muscularis propria were found under the gastric IMT. Although there have been many reported cases of gastric IMTs, almost all those cases showed huge elevated tumors. Thus, this lesion is an extremely rare IMT case presenting a superficial depressed-type appearance, like 0-IIc type early GC. Keywords: Stomach, Superficial depressed-type, IMT, CLTC-ALK fusion