Thyroid Dermopathy - An Overview

Introduction

Thyroid dermopathy is an autoimmune thyroid disease characterized by localized thickening of the skin in the pretibial area. It is related to ophthalmopathy and hyperthyroidism. It is a rare manifestation of Graves’ disease. It is one of the components of the classical triad (goiter, orbitopathy, pretibial myxedema) of Grave’s disease.

What Is Thyroid Dermopathy?

Thyroid dermopathy is also known as pretibial myxedema, localized myxedema, or infiltrative dermopathy. It is a rare disease and autoimmune in nature. Localized lesions of the skin characterize it because of the deposition of hyaluronic acid. It involves the pretibial area, ankle, and dorsum of the foot, elbows, knees, upper back, and neck.

Pretibial myxedema occurs in 5 percent of Grave’s disease and 15 percent of patients with orbitopathy and Grave’s disease. Pretibial myxedema has decreased because of the early diagnosis of Grave’s disease and hypothyroidism. Antithyroid therapy is also given earlier to treat the condition effectively. Prevalence of pretibial myxedema with thyroid eye disease occurs in 0.15 per 10,000 persons.

Pretibia means the front side of the tibia, and myxedema implies swelling of the tissues under the skin. Anyone can be affected by pretibial myxedema.

This may occur among individuals with the following condition:

• Grave’s disease.

• Hyperthyroidism or hypothyroidism.

• Eye disease.

• Between the age group of 40 to 60.

• Women.

What Are the Types of Pretibial Myxedema?

Types of pretibial myxedema include the following:

• Diffuse: In this type, nonpitting edema of the leg can be seen. It is considered the most common type of pretibial myxedema.

• Plaque: Along with nonpitting edema, raised, thick, and scaly plaque can be observed on the skin.

• Nodular: Nodules can be observed with nonpitting edema.

• Elephantiasic: In this type, lymphatic fluid accumulation occurs underneath the skin and is considered the rarest form of pretibial myxedema.

What Are the Symptoms of Grave’s Dermopathy (Pretibial Myxedema)?

Pretibial myxedema is a skin condition developing among people with Grave’s disease. It is an autoimmune thyroid disease.

Skin in Grave’s dermopathy appears as:

• Red or brown.

• Inflamed.

• Thickened.

• Orange peel texture.

• Itchy.

• Painful.

It usually affects both sides of the body in a symmetrical pattern. It sometimes involves only one side. Ninety-six percent of thyroid dermopathy cases are of Grave’s ophthalmopathy showing signs of bulging eyes, eye pain, and vision impairment.

Sometimes thyroid dermopathy is not diagnosed. Common symptoms of Grave’s disease are the following:

• Heat intolerance.

• Tremor.

• Tachycardia (fast heartbeats).

• Anxiety.

• Fatigue.

• Weight loss without reason (could be due to increased appetite).

• Frequent bowel movements.

• Goiter (swelling in front of the neck).

• Shortness of breath.

Pretibial myxedema shows a firm lump on the skin as an early symptom. Later, its size may change or merge with other lumps or nodules.

The most commonly affected sites are as follows:

• The lower part of the legs.

• Feet.

• Shins.

• The face is affected in the case of Grave’s disease or thyroid condition.

What Are the Causes of Thyroid Dermopathy?

The causes of thyroid dermopathy are as follows:

• It occurs because of autoimmune reactions as a part of Grave’s disease.

• The immune system targets cells that bind to TSH. These cells are also present in the skin, hence attacked by the immune system.

• T lymphocytes of the immune system enter the skin tissue and produce messenger proteins called cytokines. Cytokines, in turn, convey the message to cells to release too many glycosaminoglycans.

What Is the Progression of Thyroid Dermopathy?

It is generally seen in advanced conditions of thyroid diseases. It means that the underlying disease is not treated or undertreated. First, usually, hyperthyroidism develops, and later Grave’s ophthalmopathy appears, and after this, Grave’s dermopathy develops. Thyroid acropachy (soft tissue swelling and clubbing of fingers and toes) develops among 20 percent of people with Grave’s dermopathy.

What Is the Pathogenesis of Thyroid Dermopathy?

Autoantibodies cross-react with connective tissue and muscle antigens against thyroid antigens and T lymphocytes. Fibroblasts are stimulated to produce a large number of glycosaminoglycans when TSH receptor antibodies bind to receptors in connective tissue.

What Are the Clinical Features of Thyroid Dermopathy?

Clinical features of thyroid dermopathy are the following:

• Non pitting edema.

• Induration of skin- peau d’orange appearance.

• Raised, hyperpigmented, violaceous papules.

• Plaques.

• Nodules.

• Polypoid or elephantiasic-type lesions.

• Hyperhidrosis.

• Stimulated sweat.

What Are the Sites Affected by Thyroid Dermopathy?

Localized lesions occur in the following areas:

• Pretibial - 99.4 percent.

• Pretibial and feet - 4.3 percent.

• Pretibial and upper extremities - 1.1 percent.

• Preradical aspect of arms.

• Upper back.

• Shoulders.

• Pinnae.

• Nose.

• Thigh and toes.

Prediction for the pretibial area is due to local trauma with factors (gravitational forces and differentiation by fibroblasts regarding site specification).

How to Diagnose Thyroid Dermopathy?

The following tests are done to diagnose thyroid dermopathy:

• Thyroid Function Test: To know the abnormality in the hormones (T3, T4, and TSH) of the thyroid gland is done.

• Histopathological Examination: Mucin deposition and separation of regular collagen bundles by mucin can be observed when tissue is stained with alcian blue and periodic acid Schiff. Compared to normal skin, a reduced number of collagen fibers and edema can be observed. Sometimes, hyperkeratosis, acanthosis, and papillomatosis are observed.

• Ultrasonography: Used to document the thickness of pretibial myxedema (using 10-MHz ultrasonography).

How to Treat Thyroid Dermopathy?

Treatment options for thyroid dermopathy are:

• Thyroid Disorders: Treating underlying thyroid problems does not solve skin problems in thyroid dermopathy.

• Corticosteroids: Intralesional or topical corticosteroids are used to treat the condition.

• Physical Therapy: Complete decompressive therapy can be given.

• Surgical: Surgical excision can be done to treat mild cases of thyroid dermopathy.

• Medications: Somatostatin analog and insulin analog are tried as newer therapies. These help decrease glycosaminoglycans by fibroblasts.

• Immunoglobulin Treatments: Antibodies are given intravenously to treat.

• Plasmapheresis: A procedure is done to remove extra antibodies, abnormal proteins, or other harmful substances from the blood.

According to studies, partial or complete remission without treatment occurred in 70 percent of mild cases, and 58 percent of severe cases went into partial or complete remission with treatment.

Conclusion:

Thyroid dermopathy is a rare autoimmune disease related to the endocrine system. Knowing about this disease in detail helps in identifying the symptoms, if any, appear at the earliest. As hormonally related diseases are challenging to treat, in-depth knowledge helps in diagnosis and treatment and allows one to seek the doctor's help at the earliest, which leads to effective treatment. Timely help from the physician can reverse back the condition to normal effectively.