Abstract

This study was undertaken to characterize the clinicopathologic features of smooth muscle tumors of the stomach with additional regard to recent controversy over the gastrointestinal smooth mscle tumors. A total of 46 consecutive cases(47 tumors) of surgically resected or excised gastric smooth muscle tumors, were assessed for review. The criteria for malignancy applied in this study were one of the followings; (1) 5 or more mitoses/10 HPF or (2) 1-4 mitoses/10 HPF with tumor cell necrosis and 5 cm or greater in tumor size. The tumors were classified as ordinary leiomyoma in 24 cases(25 tumors), epithelioid leiomyoma in 3, cellular leiomyoma in 6, ordinary leiomyosarcoma in 10, myxoid leiomyosarcoma in 2, and epithelioid leiomyosarcoma in 1. Of the 46 cases, 13 cases(28%) were categorized as malignant smooth muscle tumor. But immunohistochemical study for S-100 protein, desmin and vimentin(5 cases), and ultrastructural study(2 cases) support that myogenic or neurogenic differentiation is evident simultaneously within the same tumor, regardless of malignancy, and that even the differentiated tumor cells seem to express such direction toward immature smooth muscle cell or nerve cell.

• Keywords: Smooth muscle tumor;Stomach;Immunohistochemistry;Ultrastructure;Histogenesis