Plexiform fibromyxoma: a clinicopathological and immunohistochemical analysis of two cases with a literature review

Abstract

Objective This article aimed to study the clinicopathological features, immunophenotypes, and differential diagnoses of plexiform fibromyxoma (PF). Methods We searched clinical and pathology databases of our hospital for patients with histologically confirmed PF from 2007 to 2020 and reviewed the relevant English and Chinese language literature. Results Two cases of PF were identified, a 67-year-old woman and a 23-year-old man. Both patients presented with melena and anemia and underwent partial gastrectomy. Histologically, the tumors exhibited a plexiform growth pattern in the gastric submucosa and the presence of bland-looking spindle cells in the fibromyxoid stroma with the formation of small blood vessels. Immunohistochemically, the two cases were strongly positive for vimentin, smooth muscle actin, and muscle-specific actin and negative for CD117, discovered on gastrointestinal stromal tumors protein 1, CD34, CD10, S100, desmin, H-caldesmon, estrogen receptor, progesterone receptor, β-catenin, and cytokeratin. Conclusions PF is a rare mesenchymal tumor of the stomach that can be distinguished from other gastrointestinal mesenchymal tumors based on its distinctive morphology and immunophenotype.