25 October 2007 – Case of the Week #98
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We thank Dr. Julia Braza, Beth Israel Deaconess Medical Center, Boston, Massachusetts (USA), for contributing this case. To contribute a Case of the Week, please email [email protected] with the clinical history, your diagnosis and microscopic images in JPG, GIF or TIFF format (send as attachments, any size, we will shrink if necessary). Please include any other images (gross, immunostains, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US dollars) for your time after we send out the case. Please only send cases with a definitive diagnosis, and preferably cases that are out of the ordinary.
Case of the Week #98
An 18 year old man with cystic fibrosis and Burkholderia dolosa infection presented with increasing fever, vomiting, dyspnea and cough. He previously was treated with multiple antibiotics, including tobramycin, minocycline, meropenem, and levofloxacin. He continued to have worsening respiratory status, and died shortly afterwards. At postmortem examination, the following findings were noted:
What is your diagnosis?
Minocycline associated “black thyroid”
Black thyroid due to pigment deposition is a well known side effect of minocycline (tetracycline) treatment. Pigment may also be deposited in bone and oral mucosa (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;97:718), and a similar effect from doxycycline has been reported (Head Neck 2006;28:373).
The pigment may be within thyroid epithelium, colloid or macrophages. Its exact nature is controversial. It stains with Fontana-Masson, resembling melanin. It has also been characterized as lipofuscin (AJCP 1983;79:738, Hum Path 1985;16:72), which may be an oxidative product of minocycline, due to its competitive inhibition with thyroid peroxidase.
Black thyroid may also be due to doxepin, lithium carbonate or tricyclic antidepressants. In these patients, the pigment is thought to be due to lysosomal accumulation of drug, not oxidation (Archives 2004;128:355).
Many reports have suggested that black thyroid is associated with thyroid pathology, but no clear relationship has yet been established. However, as papillary thyroid carcinoma in black thyroid is often unpigmented, hypopigmented foci should be thoroughly examined (Mod Path 1999;12:1181).
Despite the striking histologic findings, no specific cytologic findings have been described after fine needle aspiration (Diagn Cytopathol 2006;34:106).
Nat Pernick, M.D., President
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