IgA deficiency, a selective lack of immunoglobulin A (IgA). The most common type of immunoglobulin deficiency, it occurs in about 1 in 400 individuals. IgA is a major antibody in the saliva and in the mucous membranes of the intestines and the bronchi. It protects against bacterial and viral infections.gA deficiency, a selective lack of immunoglobulin A (IgA). The most common type of immunoglobulin deficiency, it occurs in about 1 in 400 individuals. IgA is a major antibody in the saliva and in the mucous membranes of the intestines and the bronchi. It protects against bacterial and viral infections.
Pityriasis rubra pilaris (PRP) refers to a group of skin conditions that cause constant inflammation and scaling of the skin. People with PRP have reddish, scaly patches that may occur everywhere on the body, or only on certain areas.
Atypical pityriasis rosea may be diagnosed when the rash has features such as: 1  Atypical morphology, eg papules (small bumps), vesicles (blisters), urticated plaques (weal-like), purpura (bruising), target lesions (erythema multiforme-like) 2  Large size or confluent plaques.