[FIGURE 1 AND 2 OMITTED]
Ultrastructurally, pigment (neuromelanin) is confined to lysosomes. This granular pigment stains like melanin on Fontana-Masson staining; it can also be bleached. In aspiration cytology specimens, the degenerative changes in follicular epithelial ceils found in black thyroid glands can cause nuclear hyperchromatism and chromatin clumping (figure 3). Pigment present in follicular epithelial cells in fine-needle aspirate can also be mistaken for hemosiderin-laden macrophages. It is interesting that thyroid adenomas and carcinomas fail to incorporate black pigment (figure 1). Although the concentration of minocycline-related pigment can interfere with thyroid function, it appears to be unrelated to tumorigenesis. Pigment-containing follicular epithelium has reduced thyroglobulin and ubiquitin immunoreactivity. Because of the possible antithyroid effects of minocycline, it seems advisable to monitor thyroid function in patients who are on long-term minocycline therapy.
[FIGURE 3 OMITTED]
Bell CD, Kovacs K, Horvath E, Rotondo F. Histologic, immunohistochemical, and ultrastructural findings in a case of minocycline associated "black thyroid." Endocr Pathol 2001;12:443-51.
Keyhani-Rofagha S, Kooner DS, Landas SK, Keyhani M. Black thyroid: A pitfall for aspiration cytology. Diagn Cytopathol 1991;7:640-3.
Thompson AD, Pasieka JL, Kneafsey P, DiFrancesco LM. Hypopigmentation of a papillary carcinoma arising in a black thyroid. Mod Pathol 1999;12:1181-5.
From the Department of Pathology, Beth Israel Deaconess Medical Center, Boston.
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|Title Annotation:||Pathology Clinic|
|Author:||Tahan, Steven R.|
|Publication:||Ear, Nose and Throat Journal|
|Date:||Sep 1, 2003|
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