19 February 2009 – Case of the Week #139
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Thanks to Dr. Aparna Mahajan,
Case of the Week #139
A 53 year old man with bipolar disorder experienced sudden cardiac arrest. Findings at autopsy included coronary artery disease and bilateral symmetrical enlargement of the thyroid (30g).
Micro images: #1; #2; #3; #4; #5; #6
What is your diagnosis?
Lithium induced thyroiditis
The patient had a history of lithium use.
Most follicles are small and atrophic with minimal colloid. The follicles contain desquamated follicular cells, macrophages and multinucleated giant cells. Some giant cells contain birefringent crystals consistent with calcium oxalate. These findings are compatible with lithium induced thyroid dysfunction (J Clin Pathol 1995;48:582). Lithium directly damages thyroid follicular cells, which releases thyroglobulin, which may be hydrolyzed to thyroxine, causing hyperthyroidism.
Psychotropic drugs such as lithium have arrhythmogenic effects which can be exacerbated with preexisting cardiac disease, and can cause sudden death (Can J Psychiatry 2004;49:100). However, there was no evidence of arrhythmia in this case.
The differential diagnosis includes lithium induced autoimmune thyroiditis, which has prominent lymphocytic inflammation, lymphoid follicles and Hürthle cells (J Clin Pathol 1997;50:172), which were not seen in this case.
Nat Pernick, M.D., President
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