Plexiform fibromyxoma located in the distal small bowel: A case report

Plexiform fibromyxoma (plexiform angiomyxoid myofibroblastic tumour) is a rare mesenchymal tumour primarily located in the gastric antrum. Rare cases of plexiform fibromyxoma located in the oesophagus, duodenum, gallbladder and jejunum have been reported in the literature. Histologically, this tumour is characterized by a spindle to ovoid cell proliferation with a plexiform and multinodular architecture. The stroma is myxoid, fibromyxoid or collagenous with arborizing proliferation of thin-walled capillaries. There are few mitoses, no atypia and no necrosis. Immunohistochemically, the tumour cells are positive for smooth muscle actin (SMA) and vimentin. They may be positive for CD10, desmin, caldesmon and calponin. However, they are negative for DOG1, CD117 (C-Kit), EMA, ALK, S100, CD34, and B-catenin. Here, we report the first case of plexiform fibromyxoma located in the distal ileum. This plexiform fibromyxoma was also found encompassing a probable Meckel diverticulum with foci of high-grade epithelial dysplasia without invasive carcinoma. This case report highlights the importance of considering plexiform fibromyxoma in the differential diagnosis of distal small bowel spindle cell tumours with a myxoid background.