Pretibial myxedema

Myxedema

Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease. It is more common in women than in men...

(myxoedema (UK)) is an infiltrative

Infiltration (medical)

Infiltration is the diffusion or accumulation of substances not normal to it or in amounts in excess of the normal. The material collected in those tissues or cells is called infiltrate.-Classification:...

 dermopathy

Dermopathy

Dermopathy can refer to:* Diabetic dermopathy* Graves' dermopathy, or Infiltrative dermopathy* Nephrogenic fibrosing dermopathy * Restrictive dermopathyspecial type of diseases accouting with skin and its underlying layers...

, resulting as a rare complication of Graves' disease

Graves' disease

Graves' disease is an autoimmune disease where the thyroid is overactive, producing an excessive amount of thyroid hormones...

, with an incidence rate of about 1-4% in patients.

Presentation

It usually presents itself as a waxy, discolored induration of the skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

—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

Dorsum (biology)

In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 of the feet, or as a non-localised, non-pitting edema

Edema

Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

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

Limb (anatomy)

A limb is a jointed, or prehensile , appendage of the human or other animal body....

, face

Face

The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...

, neck

Neck

The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...

, back, chest and ear

Ear

The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

s.

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

Graves' disease

Graves' disease is an autoimmune disease where the thyroid is overactive, producing an excessive amount of thyroid hormones...

, Hashimoto's thyroiditis

Hashimoto's thyroiditis

Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease in which the thyroid gland is gradually destroyed by a variety of cell- and antibody-mediated immune processes. It was the first disease to be recognized as an autoimmune disease...

, and stasis dermatitis

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.Insufficient venous...

. The serum

Blood plasma

Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

 contains circulating factors which stimulate fibroblast

Fibroblast

A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen, the structural framework for animal tissues, and plays a critical role in wound healing...

s to increase synthesis

Biosynthesis

Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...

 of glycosaminoglycan

Glycosaminoglycan

Glycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit consists of a hexose or a hexuronic acid, linked to a hexosamine .-Production:Protein cores made in the rough endoplasmic reticulum are posttranslationally...

s.

Diagnosis

A biopsy

Biopsy

A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 of the affected skin reveals mucin

Mucin

Mucins are a family of high molecular weight, heavily glycosylated proteins produced by epithelial tissues in most metazoans. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most gel-like secretions, serving functions from lubrication to cell...

 in the mid- to lower- dermis

Dermis

The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...

. There is no increase in fibroblasts. Over time, secondary hyperkeratosis

Hyperkeratosis

Hyperkeratosis is thickening of the stratum corneum, often associated with a qualitative abnormality of the keratin, and also usually accompanied by an increase also in the granular layer...

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

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.Insufficient venous...

. Elastic stains will reveal a reduction in elastic tissue.