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Common adult causes

  • “Red man syndrome”
Clinical Clues
  • Elderly men 
  • Chronic, relapsing course 
  • Pruritus +++
  • Palmoplantar keratoderma
  • Dermatopathic lymphadenopathy
Histologic clues
  • Nonspecific 
  • Acute: parakeratosis, spongiosis, moderate lymphohistiocytic infiltrate
  • Chronic: hyperkeratosis, psoriasiform acanthosis, expanded papillary dermis
Other clues
  • Increased risk of recurrence 
  • Can develop into cutaneous T-cell lymphoma: re-evaluation with serial biopsies and blood flow cytometry indicated 

Clinical Clues
  • Pre-existing lesions 
  • Spares central face
  • Nail changes: oil drop, pits, onycholysis
  • Subcorneal pustules
  • Inflammatory arthritis
Histologic clues
  • Confluent/focal parakeratosis
  • Epidermal hyperplasia with thin elongated rete ridges
  • Epidermal neutrophils
  • ↓ or absent granular layer
  • Tortuous vessels in papillary dermis
Other clues
  • Personal/family history of psoriasis
  • Withdrawal of corticosteroids, methotrexate, cyclosporine, biologics
  • Drug trigger, systemic infection or irritant contact dermatitis

  • Allopurinol 
  • Β-lactam antibiotics
  • Carbamazepine
  • Gold
  • Phenobarbital
  • Phenytoins
  • Sulfasalazine
  • Sulfonamides
Clinical Clues
  • Preceding morbilliform or scarlatiniform exanthem
  • Facial edema
  • Purpura on dependent areas 
  • Exfoliative (peeling) scale 
  • Drug rash with eosinophilia and systemic symptoms/Drug-induced hypersensitivity syndrome; fever, facial edema, peripheral eosinophilia, hepatitis, peripheral lymphadenopathy
Histologic clues
  • Pan-epidermal apoptotic keratinocytes
  • Perivascular infiltrate with eosinophils
  • Many possible patterns: lichenoid, lymphomatoid, spongiotic, interface, drug rash with eosinophilia and systemic symptoms/drug-induced hypersensitivity syndrome
Other clues
  • No history of skin disease
  • Acute onset
  • Resolves 2-6 weeks post cessation of drug trigger
  • More frequent in human immunodeficiency virus

Clinical Clues
  • Pre-existing lesions 
  • Pruritus +++
  • Excoriations 
  • Lichenification
  • Prurigo nodularis  
  • Fine scale
Histologic clues
  • Parakeratosis 
  • Mild to moderate acanthosis 
  • Variable spongiosis and dermal edema
  • Dermal eosinophils 
  • Variable lymphohistiocytic infiltrate with exocytosis of lymphocytes
Other clues
  • Personal/family history of atopy
  • High serum IgE, eosinophilia
  • Cataracts/keratoconus
  • Other stigmata of atopic dermatitis

Clinical Clues
  • Pruritus +++
  • Excoriations
  • Lichenification
  • Prurigo nodularis
  • Melanoerythroderma
  • Infiltration/edema
  • Leonine facies
  • Palmoplantar keratoderma with painful fissures
  • Alopecia 
  • Lymphadenopathy
  • Splenomegaly
Histologic clues
  • Cerebriform pleomorphic lymphocytes
  • Clustering of atypical cells in the epidermis
  • Lichenoid infiltrate
  • Histology is non-diagnostic in 30% of patients with Sézary syndrome
Other clues
  • Sézary syndrome
    European Organization of Research and Treatment of Cancer criteria:
    1. Erythroderma
    2. Clonal T-cell population in the blood and skinPlus 1 of the following
    • ≥ 1000 Sézary cells/mm3
    • CD4:CD8 ≥ 10:1
    • Increased percentage of CD4+ cells with abnormal phenotype
      • ≥ 40% CD4+/CD7–
      • ≥ 30% CD4+/CD26