A case of simultaneous, bilateral pleomorphic adenoma of the parotid glands following irradiation to the head and neck for childhood Hodgkin's disease is presented. The tumour on the side given the highest radiation exposure contained so-called tyrosine rich crystalloids (TRCs). Simultaneous salivary gland neoplasms are rare; TRCs are also an unusual finding. Simultaneous pleomorphic adenomas with TRCs confined to one tumour have never been described, and any association between TRCs and irradiation has never been commented on. The precise nature of the TRCs remains obscure. Their unilateral distribution in this case supports the hypothesis that local factors are more important in their formation than systemic factors. In conjunction with other published work, this provides circumstantial evidence that irradiation may predispose to TRC deposition.
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