Pretibial Myxedema

Updated: Jul 08, 2020
  • Author: Ranjodh Singh Gill, MD, FACP, CCD; Chief Editor: Dirk M Elston, MD  more...
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Pretibial myxedema (PTM) or, more appropriately, thyroid dermopathy, is a term used to describe localized lesions of the skin resulting from the deposition of hyaluronic acid, usually as a component of thyroid disease. Thyroid dermopathy occurs rarely. Although PTM is most often confined to the pretibial area, it may occur anywhere on the skin, especially the ankle, dorsum of the foot, knees, shoulders, elbows, upper back, pinnae, nose, and neck. [1] It is nearly always associated with autoimmune thyroid disease (see Graves Disease for more information), however PTM has been reported in patients with Hashimoto thyroiditis, primary hypothyroidism, and euthyroidism. [2, 3]

PTM is primarily of cosmetic concern and rarely causes significant morbidity. It may present as various morphological variants, including nonpitting edema (43.3%), plaque (27%), nodule (18.5%) and elephantiasis (2.8%). [4] PTM is usually asymptomatic, but pruritic or painful lesions have been reported with hyperhidrosis and hypertrichosis. [2]

Local application of corticosteroids remains the mainstay of treatment. Compression wraps or stockings that provide 20-40 mm Hg of pressure can be useful as an adjunctive therapy.

For patient education resources, see the Thyroid and Metabolism Center and Thyroid Problems.



Pretibial myxedema (PTM) occurs as a result of the deposition of hyaluronic acid in the dermis and subcutis. The precise cause of this phenomenon remains uncertain. A leading theory proposes that fibroblasts are stimulated to produce abnormally high amounts of glycosaminoglycan under the influence of cytokines due to exposure to thyrotropin receptor antibody (TRAB) and antigen-specific T cells. TRAB-binding sites are found in the plasma membranes of fibroblasts derived from the skin of patients with PTM. TRAB is present in the serum of most patients with PTM (80-100%), but it has also been found in the serum of patients without PTM. [5]

Research published in 2006 suggests that it may not be just the high level of glycosaminoglycans, but the change in percentage of the constituents of the glycosaminoglycans in the blood that leads to the development of PTM. Thyroid hormones, by means of their influence on prostaglandin metabolism, alter the synthesis and degradation of glycosaminoglycans. Prostaglandin degradation may be what is changed in the course of Graves disease, based on findings that glycosaminoglycan synthesis is reduced, as is extracellular matrix assembly in vitro with exposure to T3 excess. [6]

Cell-mediated immunity, using differentially expressed T-cell surface receptors in localized PTM, has also been proposed as having a causative role. [7] The fact that PTM frequently develops in areas of injury suggests that trauma may contribute to local fibroblast activation. In addition, extrathyroid manifestations of Graves disease often occur in the skin and eyes—fibroblasts within the orbits and skin were found to have phenotypic differences from other fibroblasts throughout the body.



Pretibial myxedema (PTM) occurs in 0.5-4.3% of patients with Graves disease. PTM has also been reported, but much less frequently, in patients with Hashimoto thyroiditis, primary hypothyroidism, and euthyroidism. [2, 3]

Women are affected more frequently than men, with a female-to-male ratio of 3.5:1. PTM may occur in children and young adults, but most cases occur in older adults, with a peak age at onset in the fifth to sixth decades of life. [8]

Lan et al analyzed the records of 44,646 outpatients with thyroid diseases seen at a single center in China between 2000 and 2006. The prevalence of PTM was 1.6%. The average age was 41.1 with a female-to-male ratio of 1:3.7. The onset of PTM was 63.9% in euthyroidism, 22% in hyperthyroidism, 11.4% in hypothyroidism, and 2.7% in unclear thyroid function. The disease course was 10 days to 10 years with an average of 37.8 months. [9]



Pretibial myxedema (PTM) is primarily of cosmetic concern and rarely causes significant morbidity. Local discomfort and difficulty wearing shoes are expected. The prognosis is good. PTM may persist for months or years but often regresses spontaneously. About 10-26% of patients experience eventual complete remission but over an average time of nine years.