Type A Thymoma : Microcystic Areas

Type A thymoma is composed of bland spindle or oval epithelial cells admixed with few or no lymphocytes. It can display a variety of architectural patterns, including microcystic foci (shown here), rosettes, glandular structures, meningioma-like whorls, storiform pattern, and hemangiopericytoma-like vascular areas. Multiple pattern are seen within the same tumor.