The Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 1 1
Copyright © 2006 by The Endocrine Society
Thymic Hyperplasia in a Patient with Graves’ Disease
K. M. Kirkeby and
A. Pont
California Pacific Medical Center, San Francisco, California 94120
Address all correspondence and requests for reprints to: Dr. Kjersti M. Kirkeby, M.D., Resident, Department of Medicine, California Pacific Medical Center, P.O. Box 7999, San Francisco, California 94120. E-mail: kjersti21{at}earthlink.net.
A 23-yr-old man who was previously healthy was evaluated after a fall. Computed tomography of the chest showed an anterior mediastinal mass. Percutaneous biopsy showed benign thymic tissue. Three months later the patient developed ophthalmopathy and signs and symptoms of hyperthyroidism. Serum-TSH level measured less than 0.004 µIU/ml (0.35–5.50 µIU/ml), serum-free T4 4.93 ng/dl (0.61–1.76 ng/dl), and serum-thyroid peroxidase antibody more than 70 IU/ml (<2 IU/ml). Radioiodine uptake was increased in a diffusely enlarged gland. Based on these findings, the patient was diagnosed with Graves’ disease. The patient was treated with radioactive iodine. His thyroid decreased substantially in size, but a repeat chest computed tomography 1 month later demonstrated persistence of the mediastinal mass (Fig. 1
). The patient complained of pain and a sensation of fullness and obstruction in his chest; thus, radical thymectomy was performed. The thymus was enlarged and measured 11.5 x 7.5 x 3 cm. Pathology revealed thymic follicular hyperplasia with focal germinal center formation.
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FIG. 1. Thymic hyperplasia in a young man with Graves’ disease presenting as an anterior mediastinal mass. The patient complained of a sensation of fullness and obstruction in his chest.
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There is a rare but well-documented association between Graves’ disease and thymic hyperplasia (1). In most cases thymic enlargement is minimal; however, it may occasionally present as an appreciable anterior mediastinal mass (2). Whereas surgical resection has been a common treatment of such a mass, the literature supports following up the mass closely (3). A decrease in size after treatment of the hyperthyroidism supports the diagnosis of thymic hyperplasia, and thymectomy can be avoided (3). Clinicians should be aware of the usually benign clinical course of thymic hyperplasia associated with Graves’ disease.
Received August 12, 2005.
Accepted October 24, 2005.
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References
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- Gunn A, Michie W, Irvine WJ 1964 The thymus in thyroid disease. Lancet 2:776–778[CrossRef][Medline]
- White SR, Hall JB, Little A 1986 An approach to mediastinal masses associated with hyperthyroidism. Chest 90:691–693[Abstract/Free Full Text]
- Budavari AI, Whitaker MD, Helmers RA 2002 Thymic hyperplasia presenting as anterior mediastinal mass in 2 patients with Graves disease. Mayo Clin Proc 77:495–499[Medline]
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