Rare adult causes
Clinical Clues
- Pruritus
- Mormorphic reddish brown papules 🡪 confluence
- Deck-chair sign
- ± Peripheral eosinophilia, lymphopenia
Histologic clues
- Dense perivascular infiltrate of lymphocytes and eosinophils in upper-mid dermis
Other clues
- Secondary to cutaneous T-cell lymphoma > atopy, other lymphomas, drugs (drug-drug interactions, acetylsalicylic acid), infection (human immunodeficiency virus, hepatitis C virus), paraneoplastic phenomenon
Clinical Clues
- Photodistributed initial lesions
- Airborne allergic contact dermatitis to compositae
Histologic clues
- Lichenoid infiltrate of lymphocytes and epidermal exocytosis
- Epidermal acanthosis and compact hyperkeratosis
- Possible lymphocyte nuclear pleomorphism
Other clues
- Drug history
- Phototesting with whole-spectrum irradiation (UVA, UVB, and visible light)
- Photopatch testing
