Actinomycosis of the thyroid gland masquerading as a neoplasm.

Actinomycetal infections involving the head and neck often pose a diagnostic puzzle to the otolaryngologist. A rare case of unilateral thyroid swelling due to actinomycosis is described. Although the clinical, laboratory and imaging studies strongly suggested a thyroid neoplasm, the histological examination revealed the presence of Actinomyces sp. in the excised lesion. The manifestations of actinomycosis of the head and neck, its pathogenesis and the difficulties encountered in the diagnosis and treatment of the disease are hereby reviewed.