Plexiform fibromyxoma: Case report and literature review

Plexiform fibromyxoma (PF) is a rare mesenchymal neoplasm which can be misdiagnosed as the gastrointestinal stromal tumor. This tumor almost formed a lobulated intramural/submucosal mass in the gastric antrum and prepyloric area. It was considered as a benign tumor that exhibited no recurrence, metastasis, or tumor-related mortality. In this study, we reported 2 cases of gastric PF. The first case was a PF patient coexisting with gastric adenocarcinoma. The second case occurred in the gastric upper body close to gastric fundus. They underwent distal gastrectomy and laparoscopic partial gastric resection, respectively. Both of them exhibited a plexiform growth pattern in the submucosa, muscularis propria, and subserosal adipose tissues. The nodules were composed of abundant myxoid or fibromyxoid matrix riching in small thin-walled blood vessels and bland-looking spindle cells. The first case partially showed staggered growth pattern of PF and adenocarcinoma. Immunohistochemically, the spindle cells were diffusely immunoreactive for SMA and vimentin, and focally immunoreactive for CD10. It was important to distinguish the PF from other spindle cell tumors involving the stomach.