There are a number of rare disorders that may present with an eczematous eruption similar to atopic dermatitis. More than 150 immunodeficiencies have been identified. Recurrent skin infections that are chronic can be the first sign of an immunodeficiency in combination with blood abnormalities. Some immunodeficiencies may closely resemble severe eczema that is not responsive to standard therapies.
X linked agammaglobulinemia is a disorder of antibody deficiency caused by a mutation in a tyrosine kinase gene which is essential for development for B lymphocytes. Affected people present with upper and lower respiratory tract, gastrointestinal, skin and other infections.
Isolated IgA deficiency is characterized by absence or near absence of serum IgA and may be drug-induced. Most patients are well; however, those who experience symptoms may manifest with allergies and atopic dermatitis in addition to autoimmune diseases.
Common variable immunodeficiency represents another antibody deficiency syndrome and is the most common after IgA deficiency. Multiple genetic defects have been found. These patients do not form a proper antibody reaction to bacterial antigens and have recurrent upper and lower respiratory tract infections.
DiGeorge syndrome is an autosomal dominant disorder that is characterized by congenital anomalies and abnormalities in the thymus. They also may present with hypocalcemia or congenital heart disease. A few of these patients may present with an eczematous dermatitis. Genetic testing for 22q11 gene can reveal deletions.
Severe combined immunodeficiency represents a group of genetic disorders with impaired cellular and humoral immunity. Multiple infections caused by bacteria and fungi characterize this disease entity. Severe eczematous dermatitis and erythroderma (diffuse redness usually associated with scaling) may also occur.
Wiskott-Aldrich syndrome is an X-linked disorder that may result in an extremely pruritic (itchy), diffuse eczematous dermatitis. The rash of Wiskott-Aldrich may be more hemorrhagic in appearance than atopic dermatitis, with petechiae (small red or purple spots caused by bleeding into the skin) and bloody crusts predominating, likely due to the platelet abnormalities associated with the disorder. The genetic mutation for this disorder is in the WASP gene which is important for our immune system cells to migrate.
Ataxia-telangiectasia is an autosomal recessive condition caused by a mutation in ATM, which is a protein that helps our cells repair its DNA. Telangiectasias are dilated blood vessels and may be present within the eye or on skin. Other findings include atopic dermatitis in context of repeated infections
The hyperimmunoglobulin E (IgE) syndrome is an immunodeficiency syndrome that may present with an eczematous dermatitis. In the hyper-IgE syndrome, the rash resembles atopic dermatitis, but inflammatory facial papules may be the predominant morphology, helping to distinguish the two disorders. Skeletal and dental anomalies are also seen, and patients often have repeated fractures and retained primary teeth. Very high levels of serum IgE (>2000 mg/dl) are seen with this disorder, although patients with severe atopic dermatitis may have equally high levels. Elevated IgE with eczema may be seen with mutations associated with mutations in STAT 3 (signal transducer and activator of transcription 3) as well as DOCK8 (dedicator of cytokinesis 8 gene) with variations in infections and other associated findings.