Erythroderma - Key Points

Definition

• Generalized erythema and scaling involving >80% of body surface area (BSA)
• Originally defined by Hebra (1868) as >90% BSA; modern usage applies >80%
• Synonyms: Exfoliative dermatitis, exfoliative erythroderma, red man syndrome (historical)

Epidemiology

• Incidence: approximately 1 per 100,000
• Male > Female (ratio 2:1 to 4:1; even higher in idiopathic subset)
• Mean age of onset: 52 years (in series including children); 60 years in adult-only series

Etiology (Adults) - Mnemonic: P-D-D-C-I

Etiology (Neonates/Infants)

• Inherited ichthyoses (congenital ichthyosiform erythroderma, epidermolytic ichthyosis)
• Netherton syndrome (bamboo hair + elevated IgE + immune defect)
• SSSS (staphylococcal scalded skin syndrome)
• Immunodeficiencies (e.g. Omenn syndrome)
• Eczematous/psoriasiform dermatitides
• Drug-induced (always consider)

Pathogenesis

• Increased number of germinative keratinocytes + increased mitotic rate
• Transit time through epidermis is shortened
• Daily scale loss increases from 500-1000 mg to 20-30 g/day
• Acute: desquamated material has marginal metabolic significance
• Chronic: significant protein loss → hypoalbuminemia, anemia of chronic disease

Clinical Features

• Generalized intense erythema with fine or coarse scaling
• Pruritus (variable - severe in atopic, CTCL, and idiopathic)
• Lichenification (atopic dermatitis)
• Palmoplantar keratoderma (idiopathic, CTCL)
• Diffuse alopecia (chronic erythroderma)
• Nail dystrophy - shedding, onycholysis, pitting (psoriasis)
• Ectropion (chronic cases)

• Psoriasis: spares central face, nail changes (pits, oil drop), subcorneal pustules, arthritis
• Atopic dermatitis: severe pruritus, lichenification including eyelids, prurigo nodularis
• Drug reactions: scarlatiniform exanthem, facial edema, purpuric in dependent areas
• CTCL (Sézary): intense pruritus, deep purple-red hue, leonine facies, palmoplantar keratoderma, lymphadenopathy, Sézary cells in blood
• Idiopathic: elderly male, chronic relapsing, severe pruritus, palmoplantar keratoderma, dermatopathic lymphadenopathy

Systemic Manifestations

• Thermoregulation: hypothermia (heat loss through dilated skin) or hyperthermia
• Cardiovascular: tachycardia, high-output cardiac failure (increased skin blood flow up to 10-15% of cardiac output)
• Peripheral edema (hypoalbuminemia + venous stasis)
• Fluid and electrolyte loss
• Hypoalbuminemia (protein loss through skin)
• Lymphadenopathy (dermatopathic - reactive; seen in ~44%, more common in idiopathic ~68%)
• Anemia of chronic disease
• Cachexia (chronic erythroderma)

Investigations

• CBC, ESR, LFT, RFT, electrolytes, serum albumin, urine R/E
• Peripheral blood smear (Sézary cells - cerebriform lymphocytes >1000/mm³ diagnostic)

• Often non-specific; may need 3-4 biopsies over time
• Psoriasis: parakeratosis, suprapapillary thinning, Munro microabscesses
• CTCL: epidermotropism, Pautrier microabscesses, atypical lymphocytes
• Atopic: spongiosis, perivascular eosinophils

Drug Causes (Common) - Table 10.3 equivalent

• Very common: Allopurinol, carbamazepine, phenytoin, phenobarbitone, sulfonamides, penicillin, gold, lithium, dapsone, isoniazid
• Biologic agents: anti-TNF drugs (rarely)
• Drug-induced erythroderma resolves in 2-6 weeks after drug withdrawal
• DRESS syndrome: erythroderma + eosinophilia + hepatitis + lymphadenopathy + fever

Management

• Bed rest, warm environment (prevent hypothermia)
• IV fluids and electrolyte correction
• High-protein diet (to compensate protein loss)
• Emollients - wet dressings, bland emollient soaks (e.g., white soft paraffin)
• Antihistamines for pruritus

• Psoriatic erythroderma: systemic retinoids (acitretin), methotrexate, cyclosporine; biologics (anti-TNF, anti-IL17, anti-IL23) in severe/refractory cases
• Atopic erythroderma: systemic corticosteroids (short course), cyclosporine, dupilumab
• Drug-induced: withdraw offending drug; systemic steroids may hasten resolution
• CTCL (Sézary syndrome): extracorporeal photopheresis (ECP) - first-line; bexarotene, vorinostat, PUVA, interferon alpha, alemtuzumab
• Idiopathic: systemic steroids, cyclosporine, methotrexate

• Mild/moderate topical corticosteroids
• Topical calcineurin inhibitors (adjunct)

Prognosis

• Depends on underlying cause
• Drug-induced: best prognosis (resolves 2-6 weeks post-drug withdrawal)
• Idiopathic: tends to be chronic, relapsing; higher relapse rate
• Overall 1-year relapse rate: 20-30%
• Mortality in acute severe erythroderma: from cardiac failure, sepsis, fluid/electrolyte imbalance

Indian-Specific Data (from IJDVL literature)

• In Indian studies, psoriasis tends to be the most common cause (unlike Western data where dermatitis leads)
• Drug-induced erythroderma - common drugs in India: dapsone, antiepileptics, antitubercular drugs (thiacetazone)
• Scabies-induced erythroderma (Norwegian/crusted scabies) is relatively more common in Indian/tropical settings

ANGIOKERATOMA - Key Points

Definition

• Benign vascular ectasias of the superficial (papillary) dermal vessels with secondary epidermal acanthosis and hyperkeratosis
• Not true neoplasms - represent dilated capillaries/venules in the papillary dermis with overlying epidermal reaction

Classification (5 Types - Mnemonic: F-M-C-S-ACD)

1. Angiokeratoma of Fordyce (Genital Angiokeratoma)

• Site: Scrotum (men), labia majora (women); rarely penis/clitoris/urethral meatus
• Age: Second to third decade; most commonly seen in older age groups
• Color: Red-purple to black
• Number: Single or multiple; arise along superficial vessels
• Associations:
  • Thrombophlebitis, varicoceles, inguinal hernias (in men)
  • Vulvar varicosities, hemorrhoids, increased venous pressure during pregnancy (in women)
• Often diffuse redness of involved area; accidental scratching causes considerable bleeding
• Histology: Communicating lacunae in subpapillary layer, lined with endothelium, connected by dilated veins
• Treatment: Primary therapy is reassurance; shave excision, cautery, laser ablation, or fulguration if desired

2. Angiokeratoma of Mibelli

• Age: Most commonly discovered in prepubertal children (ages 10-15 years)
• Site: Dorsum of fingers and toes (classic), dorsa of hands and feet, elbows, knees
• Morphology: 1-5 mm red-to-purplish black vascular papules → surface becomes hyperkeratotic over time ("telangiectatic warts")
• Inheritance: Autosomal dominant with variable penetrance; familial predisposition
• Associations: Chilblains, acrocyanosis (cold, cyanotic hands and feet); rarely ulceration of fingertips
• Histology: Hyperkeratosis, increased granular layer, dilation of subpapillary vessels forming lacunae
• DDx: APACHE (Acral Pseudolymphomatous Angiokeratoma in Children) - must be distinguished:
  • APACHE is unilateral and sporadic, no cold sensitivity
  • Histology: dense nodular lymphohistiocytic infiltrate (not primarily vascular)
  • APACHE is a variant of pseudolymphoma
• Treatment: Electrocautery, fulguration, CO2 laser ablation, long-pulse vascular laser, cryotherapy

3. Angiokeratoma Circumscriptum

• Onset: Usually infancy or childhood
• Gender: Female predominance
• Site: Trunk, arms, or legs; unilateral in most patients; commonly lower extremities, but also chest/forearm
• Morphology: Plaque of multiple discrete papules OR hyperkeratotic papules/nodules that become confluent; purple or red, well-defined; over time, a verrucous component appears; linear segmental lesions described
• Classification: Unclassified in ISSVA classification (malformation of dermal and subcutaneous capillaries and veins)
• Treatment:
  • Superficial ablative therapy (laser, cryotherapy, electrocautery) → followed by recurrence
  • Full-thickness excision is generally effective; may combine with laser therapy
• Fitzpatrick's note: Also known as capillary-lymphatic malformation (CLM); combined, well-demarcated lesion

4. Angiokeratoma Corporis Diffusum (Fabry Disease)

Genetics & Pathogenesis

• X-linked recessive lysosomal storage disease
• Gene: GLA gene mutation → Xq22
• Enzyme deficiency: α-galactosidase A deficiency
• Accumulation: Globotriaosylceramide (GL-3/Gb3) = ceramide trihexoside in lysosomes of multiple cell types: endothelial cells, erector pili muscles, dorsal root ganglion nerves, visceral organs
• Males more severely and earlier affected
• Female heterozygotes: broad spectrum - asymptomatic to severe (depends on lyonization pattern)

Cutaneous Features

• Present in 70% of males and 39% of females (Andrews: 66% males, 36% females)
• Age of onset: Males: 5-15 years (average ~20 years); Females: 8-25 years (~30 years)
• Morphology: Pinpoint to 4 mm diameter, dark-red to blue-black macular and papular lesions that do not blanch on pressure
• Hyperkeratosis: Variable; less prominent than other types; most prominent at genitalia and umbilicus
• Distribution ("bathing trunk" area): Genitals, buttocks, lower abdomen, umbilicus, groins, inner thighs, sacrum
• Additional sites: Proximal limbs (medial aspects), elbows, knees, palms and soles, distal phalanges of digits
• Mucosal: Lips (especially vermilion border), occasionally mucosal surfaces; rarely face
• Females: Usually sparsely distributed; trunk and proximal limbs most common; may occasionally occur in a dermatomal distribution

Other Cutaneous Features

• Telangiectasias (~25% of men at ~age 25; women at ~age 40)
• Vascular tortuosities of upper eyelid in 95% of patients; 40% have microaneurysms
• Hypohidrosis/anhidrosis - inability to sweat → overheating (>50% males, ~1/3 females)
• Anhidrosis in 25% of males; hyperhidrosis in ~6-12% of patients
• Lower limb edema and lymphedema; leg ulceration can occur
• Scanty hair growth

Systemic Features

• Neuropathic pain (most common initial presentation, ~2/3 of patients)
  • Begins in childhood; acroparesthesias, burning pain in hands/feet
  • Thermohypoesthesia; ~25% develop carpal tunnel syndrome
• Eyes: Corneal opacities (whorl-like/verticillata, 90% of patients), posterior capsular "spoke-like" cataracts (50%), conjunctival telangiectasias
• Kidneys: Proteinuria → renal failure (begins 2nd decade, typically presents ~age 40)
• Cardiovascular: MI, arrhythmia, angina, heart failure (around age 40); premature death
• CNS: Cryptogenic stroke (~5% of men and women, ~age 40); female patients may be misdiagnosed as MS
• GI: Abdominal pain, nausea, vomiting, diarrhea

Diagnosis

• Enzyme assay: α-galactosidase A in leukocytes, serum, fibroblasts, amniotic fluid cells
  • Males: <10% enzyme activity (definitive)
  • Females: Requires GLA gene mutation identification (enzyme levels can be normal due to lyonization)
• Histology: Dilated capillaries in papillary dermis → endothelium-lined lacunae filled with blood, surrounded by acanthotic and hyperkeratotic epidermis
• EM (Electron Microscopy): Characteristic electron-dense lamellated inclusions ("Zebra bodies") in endothelial cells, pericytes, erector pili muscles, fibroblasts; 4-6 nm alternating light and dark bands; present in angiokeratoma biopsy AND normal skin
• Special stains: Vacuoles within endothelial cells stain with toluidine blue; deposits stain with PAS and anti-GB3 antibody
• Note: Zebra bodies may be absent in skin of heterozygous females

Treatment

• Enzyme Replacement Therapy (ERT):
  • Agalsidase alfa or agalsidase beta
  • Safe; reverses substrate storage in lysosomes
  • Reduces neuropathic pain, relieves GI symptoms, stabilizes cardiomyopathy (decreases LV mass)
  • Stroke and coronary disease may still occur (at lower rate)
  • Early treatment more effective in preventing progression

Diagnosis Delay

• Angiokeratomas, acroparesthesias, corneal opacities, GI symptoms are earliest manifestations
• Diagnosis usually delayed >10 years until other stigmata appear (often diagnosed in 2nd decade)

Differential Diagnosis of Angiokeratoma Corporis Diffusum (Fitzpatrick's Table)

Histopathology (All Types)

• Marked dilatation of papillary dermal vessels (ectatic capillaries forming blood-filled lacunae)
• Acanthotic epidermis with variable hyperkeratosis
• Thinned epidermis centrally; acanthosis at edges
• Elongated rete ridges may partially or completely enclose vascular channels
• Collarette at the margin of lesions
• In Fabry disease: vacuoles in endothelial cells and pericytes (PAS+, anti-GB3+; Zebra bodies on EM)
• Stains positively with PAS and anti-GB3 antibody in Fabry

Dermoscopy

• Dilated vascular lacunae (dark red-blue to black lacunae)
• White veil/whitish structure overlying the lesions (corresponding to hyperkeratosis)
• Upper dermal vessel tortuosity (especially in Fabry)
• Thrombosed lesions may look melanoma-like on dermoscopy - important pitfall

Differential Diagnosis (Clinical)

• Melanoma (dark, thrombosed angiokeratoma most important mimic)
• Cherry angioma (no hyperkeratosis, brighter red, blanches)
• Hemangioma
• Dermatofibroma
• Wart (verrucous lesion)
• Kaposi sarcoma (especially scrotal lesions)
• Purpura/petechiae (angiokeratoma does NOT blanch on pressure - key feature)
• APACHE (for Mibelli type in children)

Treatment Summary

Key Points for Exams (IADVL-style)

• Angiokeratoma does NOT blanch on pressure (helps distinguish from telangiectasia)
• Fordyce type = scrotal angiokeratoma = most common type in general population
• Mibelli type = dorsal fingers/toes + chilblains + AD inheritance + prepubertal age
• Circumscriptum = congenital, unilateral, lower limb, female predominance - do NOT do superficial ablation (recurs)
• Fabry disease = AKA Angiokeratoma Corporis Diffusum = X-linked recessive, α-galactosidase A deficiency, bathing trunk distribution
• Zebra bodies on EM = Fabry disease (pathognomonic ultrastructural finding)
• A-1-C clinical triad of early Fabry disease: Acroparesthesias + Angiokeratomas + Corneal opacities
• Most dangerous mimicker: thrombosed angiokeratoma vs. melanoma - biopsy if in doubt
• APACHE = pseudolymphoma, unilateral, not cold-sensitive - key DDx for Mibelli type