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Other thyroid nonneoplastic

Black / pigmented thyroid

Author: Andrey Bychkov, M.D., Ph.D.

Last author update: 1 June 2015

Last staff update: 15 August 2023

Copyright: 2015-2024, PathologyOutlines.com, Inc.

PubMed Search: black thyroid

Table of Contents

Cite this page: Bychkov A. Black / pigmented thyroid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidblack.html. Accessed December 22nd, 2024.

Definition / general

Rare side effect of minocycline therapy, ~ 100 cases reported
Pigment deposition in thyroid gland in patients on minocycline (often prescribed for chronic acne) or related tetracyclines
Pigment also deposited in bone, teeth, skin, nails and oral mucosa (Diagn Cytopathol 1991;7:640)
Pigment may be lipofuscin, melanin / neuromelanin or an oxidation product of minocycline; however, lipofuscin is a predominant fraction (Diagn Cytopathol 2006;34:106)
Thyroid discoloration (dark red tissue) may also be due to psychotropic drugs such as doxepin, lithium carbonate or tricyclic antidepressants (Arch Pathol Lab Med 1994;118:79)

Terminology

Black thyroid "syndrome" is a controversial term (Thyroid 2007;17:905)

Pathophysiology

Proposed mechanisms include (Otolaryngol Head Neck Surg 1999;121:293):
- Degradation products of drug combined with lipofuscin and melanin-type pigments; minocycline accelerates and accentuates the normal process of lipofuscin accumulation (Biochem Pharmacol 1978;27:1103)
- Oxidative degradation of the drug itself (Isr J Med Sci 1988;24:51)
- Drug interaction and alteration of tyrosine metabolism
- Lysosomal dysfunction resulting in concentration of drug metabolites rather than their elimination (Am J Clin Pathol 1983;79:738)
Thyroid pigmentation by psychotropic medications is a result of lysosomal accumulation of the drugs (Arch Pathol Lab Med 1994;118:79)

Clinical features

Typically does not affect thyroid function; only a few cases reported of minocycline induced hyperthyroidism (Thyroid 2008;18:795)
Although several reports claim high rate (30 - 65%) of thyroid cancer in black thyroid, no casual relationship has been established (ORL J Otorhinolaryngol Relat Spec 2015;77:33)

Diagnosis

Incidental discovery at neck surgery or autopsy
Hypopigmented foci in gross specimens that are otherwise pigmented should be thoroughly examined to rule out papillary carcinoma (Mod Pathol 1999;12:1181, Arch Pathol Lab Med 2004;128:355)

Case reports

18 year old man with cystic fibrosis and Burkholderia dolosa infection (Case of the Week #98)
18 year old man with tumor in pigmented thyroid gland (Arch Pathol Lab Med 2004;128:355)
21 year old man with black thyroid (Postgrad Med J 1989;65:34)
35 year old woman with papillary thyroid carcinoma (Neth J Med 2007;65:185)
42 year old woman with black thyroid associated with hyalinizing trabecular tumor (Endocr J 2008;55:1109)
69 year old man and 72 year old woman (Br Med J 1976;2:1109, Intern Med 2010;49:1835)
Black thyroid resulting from short term doxycycline use (Head Neck 2006;28:373)
Follicular carcinoma associated with minocycline induced black thyroid (Endocr Pathol 1996;7:345)
Trabecular adenoma of the thyroid with black pigmentation (Thyroid 2007;17:593)

Gross description

Normal size, uniformly dark brown to jet black on surface and on cut section
Coexisting tumor tissue, if present, is frequently hypopigmented compared to rest of the gland, due to altered function of thyroid peroxidase in neoplastic cells

Gross images

Case #98

Thyroid gland with black pigment

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Black thyroid and follicular adenoma

Cut surface

Coal black coloration

Microscopic (histologic) description

Dark brown, granular, dust-like cytoplasmic pigment abundant in apical portion of follicular cells, colloid and stromal macrophages (Am J Pathol 1984;117:98)
Pigment is nonfluorescent and nonbirefringent (Arch Pathol Lab Med 2004;128:355)

Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D. and Mark R. Wick M.D.

Perinuclear brown pigment

Minocycline induced pigmentation

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Pigmented cells and colloid

Fontana-Masson

Cytology description

Dark brown, finely granular intracytoplasmic pigment in follicular cells and macrophages on Papanicolaou stain
Small round granules are darker and more regular in size and shape than hemosiderin
On Diff-Quik stain, granules are dark blue (Diagn Cytopathol 2010;38:579)
Often no specific findings when FNA is done for a thyroid nodule - neoplasms likely do not contain pigment (Diagn Cytopathol 2007;35:135)

Positive stains