Salivary gland anlage tumor ("congenital pleomorphic adenoma"). A clinicopathologic, immunohistochemical and ultrastructural study of nine cases.

Salivary gland anlage tumor (SGAT) is a polypoid lesion of the nasopharynx that presents with respiratory distress at birth or within the first few days or weeks of life. Among our nine cases, there was a male predilection (7M:2F). All tumors were in the midline and attached to the posterior pharyngeal wall by a delicate pedicle. The largest tumor measured 3 cm. A biphasic histologic pattern of squamous nests and duct-like structures at the periphery blended into solid, predominantly mesenchymal-appearing nodules centrally. The surrounding submucosal mantle of epithelial structures was consistently immunoreactive for cytokeratin and epithelial membrane antigen, whereas the stromal-like cells of the central nodules showed variable immunopositivity for cytokeratin, vimentin, and muscle-specific actin. Both components were equally reactive for salivary gland amylase. Ultrastructurally, some of the stromal-like cells had features of myoepithelial cells. The histologic and architectural features of SGAT are similar in some respects to the developing salivary gland. It is proposed that the SGAT is a probable hamartoma of minor salivary gland derivation whose origin in the nasopharynx is potentially life-threatening in an infant.