Abstract
Myoepithelioma with collagenous crystalloids occurring in the sublingual gland is described. A 40-year-old woman was admitted because of an enlarging swelling in the right side of the oral floor. Intraoral examination and magnetic resonance images revealed a localized tumorous lesion in the sublingual region. The lesion was diagnosed as pleomorphic adenoma on biopsy and was surgically excised. Histopathological examination of the tumor revealed the proliferating polygonal and spindle-shaped cells with a stroma of fibrous connective tissue. Radially arranged needle-shaped collagenous crystalloids were scattered throughout the stroma. The tumor cells were immunoreactive with cytokeratin, vimentin, muscle-specific actin, smooth muscle actin, and S-100 protein. Collagenous crystalloids were strongly positive for type III collagen immunostaining, and were ultrastructurally composed of electron-dense fibrillar materials transitional to collagenous fibers. On X-ray microanalysis, the crystalloids showed upregulation of sulfur, which was richly contained in type III collagen. These results suggest that type III collagen is involved in the formation of collagenous crystalloids.
