Adequate excision is required to prevent recurrence.
The association of crystalloids with pleomorphic adenoma was first described by Bullock in 1955. In this and subsequent cases the crystals were characterized as tyrosine because of their positive reaction with Millon's stain. Note that this is the preferred terminology as pure tyrosine crystals are needle-shaped. Van Gieson positive, slightly birefringent, Millon's negative To this list we would add the hippurate crystals shown here, seen by this department in an aspirate of a parotid cyst in a 76 year old caucasion man. The histology of the surgical specimen showed a multiloculated cyst with a double-layered, oncocytic lining and no lymphoid component.