The pyramidal lobe--a helpful criterion in the differential diagnosis of thyroid diseases.

Abstract

In cases of hyperthyroidism it may sometimes be difficult to distinguish between autonomous adenoma and autoimmune thyroiditis. For example, in some cases of Graves" (Basedow's) disease, symptoms as ophthalmopathy, pretibial myxoedema or specific antibodies may be missing. In a 39 yr old woman with subclinical symptoms of Graves' disease, the diagnosis "three adenomas of the thyroid" was made by means of a 99mTc-scintigram (Fig. 1A). One half yr later, scintigraphy was repeated, this time using ~z3I instead of 99mTc and a scinticamera with pinhole collimator in place of a scanner with honeycomb collimator. One of the formerly supposed adenomas was now clearly identified as a pyramidal lobe with the thyroglossal duct reaching into the retrolingual region (Fig. 1 B). In a retrospective evaluation of 164 123I-scintigrams that were made in the yrs 1985-1988, only two of 54 patients with thyroid adenomas had scintigraphically detectable pyramidal lobe or thyroglossal duct; in 52 of these patients, these remnants were not detectable. However, in ten of eleven cases of Graves'