|Hands showing related condition thyroid acropachy and shins of someone with pretibial myxedema|
|Classification and external resources|
Pretibial myxedema (myxoedema (UK), also known as Graves' dermopathy, thyroid dermopathy, Jadassohn-Dösseker disease or Myxoedema tuberosum) is an infiltrative dermopathy[disambiguation needed], resulting as a rare complication of Graves' disease, with an incidence rate of about 1-5% in patients.
Pretibial myxedema is almost always preceded by the ocular signs found in Graves' disease. It usually presents itself as a waxy, discolored induration of the skin—classically described as having a so-called peau d'orange (orange peel) appearance—on the anterior aspect of the lower legs, spreading to the dorsum of the feet, or as a non-localised, non-pitting edema of the skin in the same areas. In advanced cases, this may extend to the upper trunk (torso), upper extremities, face, neck, back, chest and ears.
The lesions are known to resolve very slowly. Application of petroleum jelly on the affected area could relieve the burning sensation and the itching. It occasionally occurs in non-thyrotoxic Graves' disease, Hashimoto's thyroiditis, and stasis dermatitis. The serum contains circulating factors which stimulate fibroblasts to increase synthesis of glycosaminoglycans.
There are suggestions in the medical literature that treatment with radioactive iodine for Graves' hyperthyroidism may be a trigger for pretibial myxedema which would be consistent with radioiodine ablation causing or aggravating ophthalmopathy, a condition which commonly occurs with pretibial myxedema and is believed to have common underlying features.
Other known triggers for ophthalmopathy include thyroid hormone imbalance, and tobacco smoking, but there has been little research attempting to confirm these are also risk factors for pretibial myxedema.
A biopsy of the affected skin reveals mucin in the mid- to lower- dermis. There is no increase in fibroblasts. Over time, secondary hyperkeratosis may occur, which may become verruciform. Many of these patients may also have co-existing stasis dermatitis. Elastic stains will reveal a reduction in elastic tissue.
- Schwartz, K. M.; Vahab Fatourechi; Debra D. F. Ahmed; Gregory R. Pond (1 February 2002). "Dermopathy of Graves' Disease (Pretibial Myxedema): Long-Term Outcome". Journal of Clinical Endocrinology & Metabolism. 87 (2): 438–446. doi:10.1210/jc.87.2.438.
- Prajapati VH, Mydlarski PR (March 2008). "Dermacase. Pretibial myxedema". Can Fam Physician. 54 (3): 357, 369. PMC . PMID 18337527.
- Dennis, Mark; Bowen, William Talbot; Cho, Lucy (2012). "Pre-tibial myxoedema (thyroid dermopathy)". Mechanisms of Clinical Signs. Elsevier. p. 550. ISBN 978-0729540759; pbk
- Rongioletti F, Rebora A (2007). "Mucinoses". In Bolognia JL. Dermatology. St. Louis: Mosby. pp. 616–7. ISBN 1-4160-2999-0.
- Harvey, R. D.; Metcalfe, R. A.; Morteo, C.; Furmaniak, W.; Weetman, A. P.; Bevan, J. S. (1 June 1995). "Acute pre-tibial myxoedema following radioiodine therapy for thyrotoxic Graves' disease". Clinical Endocrinology. 42 (6): 657–660. doi:10.1111/j.1365-2265.1995.tb02695.x.
- PEACEY, S.R.; FLEMMING, L.; MESSENGER, A.; WEETMAN, A.P. (1 February 1996). "Is Graves' Dermopathy a Generalized Disorder?". Thyroid. 6 (1): 41–45. doi:10.1089/thy.1996.6.41.