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June 1988

Ectopic Thyroid Tissue on Thallium/Technetium Parathyroid Scan

Arch Intern Med. 1988;148(6):1468-1470. doi:10.1001/archinte.1988.00380060232044

To the Editor.  —The article by Asp et al1 regarding the possible nonspecific (nonparathyroid, nonthyroid) localization of thallium 201 in the mediastinum is a cogent one and points out the pitfalls inherent in the interpretation of thallium 201/technetium Tc 99m pertechnetate subtraction images.Winzelberg et al2 have recently reported an instance of thallium 201 localization in a mediastinal lesion that proved to represent Hodgkin's lymphoma with histiocytic reaction. Subsequently, Linde and Basso3 observed a similar phenomenon with the demonstration of Hodgkin's disease at the site of thallium 201 accumulation in the mediastinum. It is of interest that both patients presented with hypercalcemia, equivocal results of parathyroid hormone immunoassays, and elevations in the serum concentration of 1,25-dihydroxy vitamin D. A variety of neoplastic and inflammatory lesions have been demonstrated to have the capacity to accumulate thallium 201, and this phenomenon should give one pause in the too liberal