Pretibial myxedema (myxoedema in British English, also known as Graves' dermopathy, thyroid dermopathy, Jadassohn-Dösseker disease or myxoedema tuberosum) is an infiltrative dermopathy, resulting as a rare complication of

Graves' disease Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyro ...

, with an incidence rate of about 1–5%.

Signs and symptoms

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 Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

—classically described as having a so-called ''peau d'orange'' (orange peel) appearance—on the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

aspect of the lower legs, spreading to the dorsum of the feet, or as a non-localised, non-pitting

edema Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. S ...

of the skin in the same areas. In advanced cases, this may extend to the upper trunk (torso), upper extremities,

face The face is the front of the head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affect th ...

neck The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...

, back, chest and

ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear co ...

s. The

lesions A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

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

Hashimoto's thyroiditis Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis, Hashimoto's disease and autoimmune thyroiditis, is an autoimmune disease in which the thyroid gland is gradually destroyed. Early on, symptoms may not be noticed. Over ti ...

, and

stasis dermatitis Stasis dermatitis refers to the skin changes that occur in the leg as a result of "stasis" or blood pooling from insufficient venous return; the alternative name of varicose eczema comes from a common cause of this being varicose veins. Insuffi ...

. The serum contains circulating factors which stimulate

fibroblast A fibroblast is a type of cell (biology), biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and ...

s to increase

synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...

glycosaminoglycan Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case o ...

Risk factors

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 Tobacco smoking is the practice of burning tobacco and ingesting the resulting smoke. The smoke may be inhaled, as is done with cigarettes, or released from the mouth, as is generally done with pipes and cigars. The practice is believed to hav ...

, but there has been little research attempting to confirm these are also risk factors for pretibial myxedema.

Diagnosis

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...

of the affected skin reveals

mucin Mucins () are a family of high molecular weight, heavily glycosylated proteins ( glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in ...

in the mid- to lower-

dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...

. There is no increase in

fibroblasts A fibroblast is a type of biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibrobla ...

. Over time, secondary

hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins & Cotran Pathol ...

may occur, which may become verruciform. Many of these patients may also have co-existing

. Elastic stains will reveal a reduction in elastic tissue.

Management

Many cases of pretibial myxedema, particularly cases that are mild, can be managed without specific pharmacologic treatment; approximately 50% of mild cases achieve complete remission without treatment after several years. When pharmacologic treatment is considered, topical, locally injected, or systemic corticosteroids may be used.

References

External links

{{Thyroid disease Mucinoses Thyroid William Osler