THE THREE main and distinct clinical types of thyroiditis are (1) the subacute (pseudotuberculous or giant cell) variety, (2) struma lymphomatosa (Hashimoto's thyroiditis) and (3) Riedel's struma.1 Subacute thyroiditis resolves promptly and completely in response to roentgen therapy; some, and possibly most, cases of struma lymphomatosa respond favorably to roentgen rays, but Riedel's struma is unaffected by irradiation.
Subacute thyroiditis is a self-limited disease of unknown causation. It has a variable course of weeks or months and eventually subsides without treatment and without significant interference with the function of the thyroid.This type of thyroiditis has been variously named tuberculous, pseudotuberculous or giant cell thyroiditis because of the histologic appearance of pseudotubercles with giant cells. Tubercle bacilli cannot be demonstrated in the lesions, and the cause of the disease is unknown. Bacteria have not been demonstrated in the thyroid. The possibility that it represents a virus infection