[Plexiform angiomyxoid myofibroblastic tumor of stomach].

Objective: To study the clinicopathologic features, immunophenotype and differential diagnosis of plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach.

Methods: The clinical and pathologic findings of 3 cases of PAMT in the gastric antrum were retrospectively analyzed. Immunohistochemical study was carried out and the literature was reviewed.

Results: The age of patients ranged from 31 to 47 years. The male-to-female ratio was 1:2. The clinical presentation included epigastric pain and distension. Endoscopically, the tumor mass protruded into the gastric cavity at the antrum and ranged from 4.5 cm to 8.0 cm in greatest dimension. One of the tumors studied was associated with surface ulceration. Histologically, the tumors were located in the gastric wall. They were composed of bland spindle cells and small vessels arranged in a plexiform or nodular pattern within a myxoid stroma. Immunohistochemical study showed that the spindle cells were consistently positive for smooth muscle actin and muscle-specific actin. There was focal staining for h-caldesmon, desmin in case 3 and focal positive for epithelial membrane antigen, CAM5.2 in case 1. Further, CD10 and progesterone receptor were positive in case 3.

Conclusions: PAMT represents a rare novel mesenchymal tumor of the stomach, with a propensity of gastric antral involvement. The distinctive pathologic features help to differentiate this entity from other benign and malignant tumors.