Cutaneous lupus erythematosus

What is cutaneous lupus erythematosus?

Cutaneous lupus erythematosus (CLE) is the term doctors use when a disease called lupus erythematosus affects the skin. About two-thirds of patients with lupus will develop CLE. Many patients with CLE also have other organs, such as the heart, lungs, kidney, muscles, and joints, that are also affected by lupus.

Lupus erythematosus is an autoimmune disease that leads to increased inflammation in many parts of the body. The inflammation, or damage, can be caused directly by immune cells or specialized proteins called antibodies that are produced by immune cells. In most patients with lupus, the immune system makes anti-nuclear antibodies (ANA), which are given this term because they stick to the nucleus of normal cells.

The skin

Your skin is the largest organ in your body. It is made up of three layers: epidermis, dermis, and subcutaneous fat. The outermost, visible layer of the skin is called the epidermis. The cells that make up the epidermis include squamous cells, basal cells, melanocytes, Merkel cells, and cells of the immune system. The squamous cells in the epidermis produce a material called keratin, which makes the skin strong, waterproof, and provides protection from toxins and injuries.

The dermis is below the epidermis, and it is separated from the epidermis by a thin layer of tissue called the basement membrane. The dermis contains blood vessels and nerves. Below the dermis is a layer of fat called subcutaneous adipose tissue (see picture below).

skin normal no adenexa

What causes lupus erythematosus?

Lupus erythematosus is caused by a combination of genetic, environmental, and immune system factors, which lead to increased inflammation.

  • Genetic: Researchers have identified many genes that are associated with an increased risk for developing lupus erythematosus. Patients with lupus erythematosus often have a family member who is also affected.
  • Environmental: Lupus erythematosus can be triggered by environmental factors in individuals who are genetically predisposed to this disease. One of the most common triggers is sun exposure, as well as cigarette smoking, hormones, infections, and some medications.
  • Immune system: Lupus erythematosus is thought to involve multiple parts of the immune system including antibodies and proteins, which lead to increased inflammation. Specialized immune cells called T-cells, and components of our cellular immune system play an important role in the development and maintenance of lupus erythematosus

Types of cutaneous lupus erythematosus

Cutaneous lupus erythematosus can present with a broad range of skin lesions. Doctors divide these skin lesions into three categories or types:

  • Acute: This form most often presents as a red rash on the cheeks and nose, which is called a “butterfly rash”. Most patients with acute CLE will eventually develop lupus in other parts of the body.
  • Subacute: This form most often presents as a red, raised, scaly rash on sun-exposed areas of the body. Skin lesions tend to be ring-like and may look similar to psoriasis or eczema. Approximately 10-15% of patients with this form of CLE eventually develop lupus in other parts of the body.
  • Chronic/Discoid: This form often starts with a red, round, scaly rash on the scalp, face, ears, and other sun-exposed areas. Skin lesions may heal but leave discolored scars as well as hair loss on the scalp. Approximately 5-10% of patients with this form eventually develop lupus in other parts of the body.

How is cutaneous lupus erythematosus diagnosed?

The diagnosis of CLE requires information from a variety of sources including your medical history, a physical examination, blood tests, and a skin biopsy. Your medical team will work collaboratively to gather and share this information in order to determine the correct diagnosis.

Your biopsy report for cutaneous lupus erythematosus

A skin biopsy is a procedure where a small sample of tissue is removed and sent to a pathologist for examination under a microscope. The tissue sample can be used to look for inflammation, tissue damage, and abnormal antibodies in the skin.

Common microscopic features of cutaneous lupus erythematosus:

  • Vacuolar interface change: This term is used to describe damage at the bottom of the epidermis where the squamous cells meet the dermis.
  • Civatte or colloid bodies: A civatte or colloid body is a damaged squamous cell. As a squamous cell dies it becomes small and turns bright pink.
  • Thickening of the basement membrane: The basement membrane is the thin layer of tissue that separates the epidermis from the dermis. In CLE, it becomes abnormally thick.
  • Increased dermal mucin: The dermis is a thick layer of connective tissue just below the basement membrane. CLE results in damage to the dermis by inflammatory cells and increased production of a substance called mucin.

Direct immunofluorescence

Direct immunofluorescence (DIF) is a test that pathologists perform to look for specific proteins in a tissue sample. Unlike most tissue samples, which are examined using normal light, DIF tissue samples are examined using fluorescent light. This makes it easier for your pathologist to see any abnormal proteins in the sample.

In patients with CLE, tissue samples examined from the DIF test will often show increased amounts of immune system-related proteins in the area of the basement membrane. These proteins include IgG, IgM, IgA, and C3.

by Bret Kenny and Allison Osmond MD FRCPC (updated September 8, 2021)
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