September 07, 2012
2 min read

'Hashitoxicosis' revisited

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In September 2011, I posted a blog about a 17-year-old girl in whom the thyroid gland increased in size a few months after radioactive iodine therapy for Graves’ disease. The gland decreased in size on steroid therapy, and by January 2012, she was clinically and biochemically euthyroid and the gland had returned to normal size. However, 2 months later, the gland began to enlarge again.

An MRI with and without contrast revealed “heterogeneous in intensity and multiple small nodules.” There was also a 1.2x1.4x1.5 cm nodule at the thyroid isthmus. This larger nodule was subsequently biopsied but the pathology report was, to put it mildly, inconclusive.

I referred her to an endocrine surgeon with a recommendation to consider total thyroidectomy, which was performed just as one would expect from an accomplished endocrine surgeon.

The pathology report was a mixed blessing. A diagnosis of “Papillary adenocarcinoma arising in a background of advanced Hashimoto’s thyroiditis” was made. Fortunately all surgical resection margins and six peri-thyroid lymph nodes were negative for malignancy.

My patient is recovering well from her surgery.

Did she have the papillary carcinoma when she had hyperthyroidism?

How common is it for a patient to develop Hashimoto’s thyroiditis after radioactive iodine for Graves’ disease?

I have done what I think is an extensive search on PubMed and did not find any good answers to those questions. It is well recognized that papillary carcinoma does occur in a small percentage of patients with Graves’ disease and there is a higher percentage of patients with thyroiditis who develop papillary carcinoma. The two articles cited below are the closest I could find that might be helpful.

What did I learn from this case? Nothing definitive as yet — I will wait for your comments on this blog. One thing I will consider in future patients with thyrotoxicosis and an enlarged thyroid without an obvious nodule on physical examination is to order an ultrasound before proceeding to RAI therapy. Thyroid antibodies will also be measured, with a markedly elevated titer of thyroid peroxidase antibodies — an added clue to the possibility of a malignancy. That said, I anticipate that the yield for early diagnosis of papillary thyroid carcinoma in a patient with Graves’ disease will be low.

For more information:

Henry JF, et al. Thyroperoxidase immunodetection for the diagnosis of malignancy on fine-needle aspiration of thyroid nodules. World J Surg. 1994 Jul-Aug;18(4):529-34.PMID:7725740

Paşcanu I, et al. Thyroid nodule with Hashimoto thyroiditis in childhood - a challenging experience.

Borda A, Bănescu C.Rom J Morphol Embryol. 2008;49(4):541-5.PMID:19050804