DRUG-RELATED PIGMENTATION OF THE THYROID-ASSOCIATED WITH PAPILLARY CARCINOMA

Black pigmentation of the thyroid attributed to minocycline hydrochlor ide is known, but to our knowledge, pigmentation associated with antid epressants has not been reported. We studied four patients with papill ary carcinoma associated with thyroid pigmentation; two had received m inocycline therapy, and two had received long-term treatment with anti depressants. The thyroids of patients who had been treated with minocy cline were black, with pigment primarily in nontumorous tissue. The th yroids associated with antidepressant therapy were dark red, with pigm ent in both tumorous and nontumorous tissue. All four cases were posit ive for periodic acid-Schiff, periodic acid-Schiff with diastase predi gestion, and Schmorl's stains and negative for Prussian blue; the resu lts differed from those found with Fontana's technique. Minocycline-re lated pigmentation appears to imply a role for the iodide peroxidase s ystem in the accumulation of pigment, whereas pigmentation attributed to intake of antidepressants appears to result from lysosomal accumula tion of the drug itself.