Tyrosine-rich crystalloids in neoplasms and tissues of the head and neck.

Tyrosine-rich crystalloids were identified in three benign mixed tumors of the parotid gland, one terminal duct adenocarcinoma of a minor salivary gland, and the fibrous connective tissue of two laryngectomy specimens. Light and electron microscopic studies showed the crystalloids to be composed of irregular deposits of amorphous electron-dense material. In the salivary gland tumors this material was commonly associated with interstitial collagen and was found in greatest abundance near myoepithelial cells. This proximity suggests that the tyrosine-rich crystalloids result from the precipitation on stromal collagen of products secreted by neoplastic myoepithelial cells.