Black thyroid adenoma: Clinical, histochemical, and ultrastructural features

Rumelia Koren, Joelle Bernheim, Pinchas Schachter, Ariel Schwartz, Anette Siegal, Rivka Gal

Research output: Contribution to journalArticlepeer-review


A 22-year-old woman with a 'hot' thyroid nodule who was being treated with minocycline for severe acne vulgaris is presented. A partial thyroidectomy specimen revealed a black adenoma. Microscopically, the black pigment was found in the follicular cells and the colloid of the adenoma. The pigment was bleached with potassium permanganate and was Fontana-Masson stain positive. It was negative for iron, periodic acid-Schiff, and acid-fast Ziehl-Neelsen stains. All these feature suggest a melanin-like pigment. However, electron microscopic examination revealed a dense osmophilic material present within the lysosomes of the follicular cells. No melanosomes were present. Twenty-six previously reported cases are reviewed, and the possible mechanisms for the deposition of the pigment in the adenoma and its relation to minocycline degradation products are discussed.

Original languageEnglish
Pages (from-to)80-84
Number of pages5
JournalApplied Immunohistochemistry
Issue number1
StatePublished - 2000
Externally publishedYes


  • Adenoma
  • Black thyroid
  • Minocycline


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