Page 637 - Clinical Immunology_ Principles and Practice ( PDFDrive )

612 Part five Allergic Diseases

TABLE 44.1 Differential Diagnosis of TABLE 44.2 Clinical features of
atopic Dermatitis atopic Dermatitis
Congenital Disorders Major features
• Netherton syndrome • Pruritus
• Familial keratosis pilaris • Facial and extensor involvement in infants and children
• Flexural lichenification in adults
Chronic Dermatoses • Chronic or relapsing dermatitis
• Seborrheic dermatitis • Personal or family history of atopic disease
• Contact dermatitis (allergic or irritant)
• Nummular eczema Minor features
• Psoriasis • Xerosis
• Ichthyoses • Cutaneous infections
• Nonspecific dermatitis of the hands or feet
infections and infestations • Ichthyosis, palmar hyperlinearity, keratosis pilaris
• Scabies • Pityriasis alba
• Human immunodeficiency virus (HIV)–associated dermatitis • Nipple eczema
• Dermatophytosis • White dermatographism and delayed blanch response
• Anterior subcapsular cataracts
Malignancies • Elevated serum immunoglobulin E (IgE) levels
• Positive immediate-type allergy skin tests
• Cutaneous T-cell lymphoma (mycosis fungoides/Sézary syndrome)
• Letterer-Siwe disease Modified from Hanifin JM, Rajka G. Diagnostic features of atopic dermatitis. Acta
Derm Venereol (Stockh) 1980;92:44–7.
autoimmune Disorders
• Dermatitis herpetiformis
• Pemphigus foliaceus
• Graft-versus-host disease (GvHD) immune response to herpes simplex virus. In addition, genetic
• Dermatomyositis
variants in IFN-γ regulatory factor 2 (IFN-γR2) have been shown
immunodeficiencies to be associated with ADEH and may contribute to abnormal
• Wiskott-Aldrich syndrome (WAS) immune responses to herpes simplex virus.
• Severe combined immunodeficiency syndrome (SCID) Superimposed dermatophytosis may contribute to cutaneous
• Hyperimmunoglobulin E (IgE) syndrome (HIES) inflammation in AD. The opportunistic yeast Malassezia sym-
• Dedicator of cytokinesis 8 (DOCK8)–associated immunodeficiency podialis (previously Pityrosporum ovale) has been associated with
• Tyrosine kinase 2 (TYK2) deficiency a predominantly head and neck distribution of AD.
• Immune dysregulation, polyendocrinopathy, enteropathy X-linked
(IPEX) syndrome Systemic Complications
Metabolic Disorders A significant number of patients with AD do not outgrow their
• Zinc deficiency disease and can have systemic inflammation with increased risk
6
• Pyridoxine (vitamin B6) and niacin deficiency for systemic diseases, including cardiovascular disease, rheu-
7
• Multiple carboxylase deficiency matoid arthritis, and/or inflammatory bowel disease.
• Phenylketonuria
Psychosocial Implications
Patients with AD frequently respond to stress or frustration with
itching and scratching. Stimulation of the central nervous system
AD. Preferential adherence of this organism in AD may be related (CNS) may intensify cutaneous vasomotor and sweat responses
to expression of adhesins, such as fibronectin and fibrinogen, and contribute to the itch–scratch cycle. Scratching can be associ-
in inflamed skin. Recurrent pustulosis has become a significant ated with significant secondary gain or with a strong habitual
problem for a number of patients, especially with the emergence component. Severe disease can lead to problems with self-esteem
of methicillin-resistant S. aureus (MRSA) as an important and social interactions. Sleep abnormalities are common and
pathogen in AD. can contribute to impaired quality of life of patients and family
Viral infections in AD include herpes simplex, molluscum members, even when the skin disease appears to be in remission.
contagiosum, and human papillomavirus infections. Patients
who have atopic dermatitis with eczema herpeticum (ADEH) Differential Diagnosis
have more severe disease, increased body surface area affected, A number of diseases can be confused with AD (see Table 44.1).
and an increase in biomarkers, including circulating eosinophil Immunodeficiency with eczematous rash includes immune
counts, serum immunoglobulin E (IgE), thymus and activation- dysregulation, polyendocrinopathy, enteropathy X-linked (IPEX)
regulated chemokine, and cutaneous T cell–attracting chemokine, syndrome. IPEX results from mutations of FOXP3, a gene located
compared with patients with AD who do not have a history of on the X chromosome that encodes a DNA-binding protein
EH. Patients with ADEH also have more cutaneous infections required for development of regulatory T cells (Tregs). Patients
caused by S. aureus or molluscum contagiosum virus and are may present with enteropathy, type 1 diabetes, thyroiditis,
more likely to have a history of asthma, as well as food and hemolytic anemia, and/or thrombocytopenia. Wiskott-Aldrich
inhalant allergies. Patients with ADEH have reduced interferon-γ syndrome (WAS) is an X-linked recessive disorder characterized
(IFN-γ) production. IFNγ and IFNγR1 SNPs are significantly by an eczematous rash, associated with thrombocytopenia along
associated with ADEH and may contribute to an impaired with variable abnormalities in humoral and cellular immunity