Primary Immunodeficiency Diseases: Cutaneous Manifestations
Introduction
Primary immunodeficiency diseases (PIDs), also called inborn errors of immunity, are inherited disorders affecting the development and/or function of the immune system. While traditionally considered rare, over 450 distinct PIDs are now recognized, affecting approximately 1 in 1,000-5,000 individuals.
The skin is frequently involved in PIDs, serving both as a target of infection due to immune compromise and as a site of immune dysregulation causing inflammatory and autoimmune manifestations. Dermatologists often play a crucial role in early recognition of these conditions.
Classification of Primary Immunodeficiencies
IUIS Classification Overview
Loading diagram...
Severe Combined Immunodeficiency (SCID)
Overview
SCID represents the most severe form of PID, characterized by profound deficiency of T cells with variable B and NK cell involvement.
Loading diagram...
Cutaneous Manifestations
| Manifestation | Mechanism | Clinical Features |
|---|
| Omenn syndrome | Oligoclonal T cell expansion | Erythroderma, alopecia, lymphadenopathy |
| Graft-versus-host disease | Maternal T cell engraftment | Erythematous rash, desquamation |
| Infections | Absent T cell immunity | Candidiasis, viral infections |
| BCG-itis | Disseminated BCG | Ulcerating nodules (if vaccinated) |
Omenn Syndrome
| Feature | Description |
|---|
| Genetics | Hypomorphic RAG1/2, Artemis mutations |
| Skin | Generalized erythroderma, exfoliative dermatitis |
| Hair | Alopecia |
| Other | Hepatosplenomegaly, lymphadenopathy, eosinophilia, elevated IgE |
| Prognosis | Fatal without HSCT |
Wiskott-Aldrich Syndrome (WAS)
Clinical Features
Loading diagram...
| Feature | Details |
|---|
| Genetics | X-linked; WAS gene (WASP protein) |
| Eczema | Severe, often bloody (thrombocytopenia); from infancy |
| Infections | Pyogenic bacteria, Pneumocystis, herpesviruses |
| Bleeding | Petechiae, bruising, bloody diarrhea |
| Autoimmunity | Hemolytic anemia, vasculitis |
| Malignancy risk | Lymphoma (10-20%) |
| Treatment | HSCT, gene therapy |
Hyper-IgE Syndromes
STAT3-Deficient (AD-HIES, Job Syndrome)
Loading diagram...
| Feature | STAT3-Deficient (AD) | DOCK8-Deficient (AR) |
|---|
| Inheritance | Autosomal dominant | Autosomal recessive |
| Gene | STAT3 | DOCK8 |
| Skin | Cold abscesses, eczema | Severe eczema, viral warts, HSV |
| Infections | Staph, Candida | Severe viral (HPV, HSV, molluscum) |
| IgE | Very high (>2,000) | Very high |
| Eosinophilia | Yes | Yes |
| Viral susceptibility | Limited | Severe |
| Malignancy | Lymphoma | Lymphoma, SCC |
| Skeletal | Fractures, scoliosis, retained teeth | Minimal |
Cold Abscesses
A hallmark of STAT3-HIES:
- Staphylococcal abscesses without typical signs of inflammation
- "Cold" = lack of warmth, erythema, tenderness
- Due to defective Th17 response and neutrophil chemotaxis
Chronic Granulomatous Disease (CGD)
Pathophysiology
Loading diagram...
Cutaneous Manifestations
| Manifestation | Description |
|---|
| Skin abscesses | Staph aureus, Serratia, Aspergillus |
| Lymphadenitis | Suppurative, often granulomatous |
| Lupus-like rash | Discoid lesions (carrier females) |
| Seborrheic dermatitis | Common |
| Granulomatous inflammation | Sterile granulomas in skin |
| Perianal disease | Fistulae, abscesses |
Characteristic Pathogens
| Type | Organisms |
|---|
| Bacteria | S. aureus, Serratia, Burkholderia, Nocardia |
| Fungi | Aspergillus (most common cause of death) |
| Key feature | Catalase-positive organisms |
Complement Deficiencies
Clinical Manifestations
| Deficiency | Inheritance | Key Manifestations |
|---|
| C1q, C1r, C1s | AR | SLE-like disease (90%) |
| C2 | AR | SLE (50%), pyogenic infections |
| C3 | AR | Severe pyogenic infections, GN |
| C5-C9 (MAC) | AR | Neisserial infections |
| Properdin | X-linked | Neisserial meningitis |
| C1-inhibitor (HAE) | AD | Hereditary angioedema |
Hereditary Angioedema (HAE)
Loading diagram...
| Feature | Details |
|---|
| Type I | Low C1-INH level (85%) |
| Type II | Normal level, dysfunctional protein (15%) |
| Type III | Normal C1-INH, factor XII mutations (estrogen-sensitive) |
| Key distinction | Does NOT respond to antihistamines or epinephrine |
| Treatment | C1-INH concentrate, icatibant (bradykinin blocker), lanadelumab |
IPEX Syndrome
Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-linked
Loading diagram...
| Feature | Details |
|---|
| Gene | FOXP3 (X-linked) |
| Mechanism | Lack of functional Tregs → uncontrolled inflammation |
| Skin | Eczema (often severe), erythroderma, alopecia |
| Onset | Infancy |
| Prognosis | Fatal without HSCT |
When to Suspect a PID
Warning Signs
Loading diagram...
Skin Findings Suggesting Specific PIDs
| Skin Finding | Consider |
|---|
| Severe eczema from birth | WAS, IPEX, Omenn, DOCK8, STAT3-HIES |
| Cold abscesses | STAT3-HIES (Job syndrome) |
| Extensive warts/molluscum | DOCK8, GATA2, WHIM syndrome |
| Recurrent HSV/VZV | DOCK8, NK cell deficiencies |
| Mucocutaneous candidiasis | CMC (STAT1 GOF), CARD9, APECED |
| Granulomas (sterile) | CGD, CVID |
| Lupus-like rash | Complement deficiency, CGD carriers |
| Angioedema without urticaria | HAE (C1-INH deficiency) |
| Telangiectasias (conjunctival, skin) | Ataxia-telangiectasia |
Summary
Loading diagram...
Key Clinical Pearls
| Topic | Pearl |
|---|
| Severe infant eczema | Consider WAS, IPEX, DOCK8, Omenn |
| Cold abscesses | Pathognomonic for STAT3-HIES (Job) |
| Catalase-positive organisms | Think CGD |
| Recurrent Neisseria | Complement (C5-C9) or properdin deficiency |
| HAE | Doesn't respond to antihistamines or epinephrine |
| Extensive warts | DOCK8, GATA2, WHIM syndrome |
| Lupus-like + infections | Complement deficiency |
Cross-References