Skin Manifestations of Internal Disease¶
Chapter 61 - Harrison's Principles of Internal Medicine
KEY CLINICAL POINTS¶
- Skin manifestations often reflect underlying systemic diseases.
- Papulosquamous lesions include psoriasis, eczema, and fungal infections.
- Erythroderma is a generalized redness of the skin with associated systemic symptoms.
- Alopecia can be a sign of autoimmune diseases, infections, or malignancies.
- Telangiectasias are dilated blood vessels often associated with systemic conditions.
- Hypopigmentation and hyperpigmentation can indicate autoimmune disorders, infections, or metabolic diseases.
- Vesicles and bullae are common in autoimmune blistering diseases and infections.
- Exanthems are acute eruptions often due to viral infections or medications.
- Urticaria and angioedema are allergic reactions with varied etiologies.
- Papulonodular lesions include benign and malignant conditions like nevi and tumors.
- Purpura indicates bleeding disorders, vasculitis, or coagulation abnormalities.
- Ulcers may result from vascular disease, infections, or autoimmune conditions.
PAPULOSQUAMOUS LESIONS¶
Common in psoriasis, eczema, and fungal infections. Lesions are red, scaly, and may coalesce into plaques.
Table 61-1: Causes of Papulosquamous Lesions¶
| Lesion Type | Associated Conditions |
|---|---|
| Psoriasis | Autoimmune, genetic, environmental factors |
| Eczema | Allergic, irritant, atopic dermatitis |
| Fungal Infections | Tinea, ringworm, candidiasis |
| Lichen Planus | Autoimmune, viral, drug reactions |
| Pityriasis Rosea | Viral, benign, self-limiting |
ERYTHRODERMA¶
Generalized redness of the skin with systemic symptoms like fever and pruritus. Common causes include psoriasis, eczema, and drug reactions.
Table 61-2: Causes of Erythroderma¶
| Cause | Clinical Features |
|---|---|
| Psoriasis | Scaly, red plaques, nail changes |
| Eczema | Itching, oozing, crusting |
| Drug Reaction | Acute onset, widespread redness |
| Infections | Fever, lymphadenopathy, systemic symptoms |
ALOPECIA¶
Hair loss can indicate autoimmune diseases (e.g., alopecia areata), infections, or malignancies. Patterns vary by cause.
Table 61-3: Causes of Alopecia¶
| Type | Associated Conditions |
|---|---|
| Alopecia Areata | Autoimmune, stress, genetic factors |
| Androgenetic Alopecia | Genetic, hormonal |
| Telogen Effluvium | Stress, nutritional deficiency |
| Scarring Alopecia | Lupus, lichen planus, infections |
TELANGIECTASIAS¶
Dilated blood vessels often seen in rosacea, systemic sclerosis, or hereditary conditions. May be associated with telangiectasia syndromes.
Table 61-4: Causes of Telangiectasias¶
| Cause | Clinical Features |
|---|---|
| Rosacea | Facial redness, telangiectasia |
| Systemic Sclerosis | Skin thickening, telangiectasia |
| Hereditary Syndromes | Multiple telangiectasias, organ involvement |
HYPOPIGMENTATION AND HYPERPIGMENTATION¶
Hypopigmentation may indicate vitiligo, III , or III . Hyperpigmentation is common in melasma, Addison's disease, or post-inflammatory changes.
Table 61-5: Causes of Hypopigmentation¶
| Condition | Clinical Features |
|---|---|
| Vitiligo | White patches, autoimmune |
| Tinea Versicolor | Scaly, hypopigmented patches |
| Leprosy | Numbness, hypopigmented plaques |
Table 61-6: Causes of Hyperpigmentation¶
| Condition | Clinical Features |
|---|---|
| Melasma | Brown patches, sun exposure |
| Addison's Disease | Hyperpigmentation, hypotension |
| Post-Inflammatory Hyperpigmentation | After skin injury or inflammation |
VESICLES AND BULLAE¶
Blistering disorders include pemphigus, bullous pemphigoid, and infections like herpes zoster. Vesicles may be sterile or contain infectious agents.
Table 61-7: Causes of Vesicles/Bullae¶
| Cause | Clinical Features |
|---|---|
| Pemphigus | Flaccid blisters, autoimmune |
| Bullous Pemphigoid | Tense blisters, elderly patients |
| Herpes Zoster | Vesicles in dermatomal distribution |
| Staphylococcal Scalded Skin Syndrome | Flaccid blisters in infants |
EXANTHEMS¶
Acute eruptions often due to viral infections (e.g., measles, rubella) or medications. May include morbilliform, scarlatiniform, or urticarial patterns.
Table 61-8: Causes of Exanthems¶
| Cause | Clinical Features |
|---|---|
| Measles | Fever, rash, Koplik spots |
| Rubella | Fever, rash, lymphadenopathy |
| Drug Reactions | Acute onset, widespread rash |
| Viral Infections | Fever, systemic symptoms |
URTICARIA AND ANGIODEMA¶
Urticaria is transient, itchy wheals. Angioedema is deeper swelling. Both can be allergic or non-allergic in origin.
Table 61-9: Causes of Urticaria¶
| Cause | Clinical Features |
|---|---|
| Allergic Reactions | Pruritus, wheals |
| Infections | Fever, systemic symptoms |
| Autoimmune | Chronic urticaria, autoimmune diseases |
PAPULONODULAR LESIONS¶
Elevated skin lesions include nevi, tumors, and inflammatory conditions. Color and morphology vary by cause.
Table 61-10: Papulonodular Lesions by Color¶
| Color Group | Examples |
|---|---|
| White | Calcinosis cutis, osteoma cutis |
| Skin-Colored | Rheumatoid nodules, neurofibromas |
| Pink/Translucent | Amyloidosis, papular mucinosis |
| Yellow | Xanthomas, necrobiosis lipoidica |
| Red | Angiokeratomas, bacillary angiomatosis |
PURPURA¶
Purpura indicates bleeding disorders, vasculitis, or coagulation abnormalities. May be non-palpable or palpable.
Table 61-11: Causes of Purpura¶
| Cause | Clinical Features |
|---|---|
| Thrombocytopenia | Petechiae, purpura |
| Vasculitis | Palpable purpura, systemic symptoms |
| Infections | Purpura with fever, systemic symptoms |
ULCERS¶
Ulcers may result from vascular disease, infections, or autoimmune conditions. Common sites include lower extremities and mucous membranes.
Table 61-12: Causes of Mucocutaneous Ulcers¶
| Cause | Clinical Features |
|---|---|
| Peripheral Vascular Disease | Ischemic ulcers, leg pain |
| Livedoid Vasculopathy | Painful ulcers, leg involvement |
| Infections | Ulcers with purulent discharge |