Photosensitivity

Excerpt

Photosensitivity refers to various symptoms, diseases, and conditions (photodermatoses) caused or exacerbated by exposure to sunlight. It is classified into five categories: primary photodermatosis, exogenous photodermatosis, photo-exacerbated dermatoses, metabolic photodermatosis, and genetic photodermatosis.

Primary or autoimmune photodermatoses

1. Polymorphic light eruption

2. Juvenile spring eruption

3. Actinic folliculitis

4. Actinic prurigo

5. Solar urticaria

6. Chronic actinic/photosensitivity dermatitis

7. Hydroa vacciniforme (associated with Epstein-Barr virus)

Exogenous or drug/chemical-induced photodermatoses

1. Drug-induced photosensitivity: common photosensitizing drugs are thiazides, tetracyclines, non-steroidal anti-inflammatory drugs (NSAIDs), phenothiazines, voriconazole, quinine, vemurafenib, and many others

2. Photocontact dermatitis: due to phototoxic chemicals such as psoralens in plants, vegetables, fruit; fragrances in cosmetics; sunscreen chemicals; dyes and disinfectants

3. Pseudoporphyria: induced by drugs and/or renal insufficiency

Photo-exacerbated or photo-aggravated dermatoses

Usually:

1. Cutaneous lupus erythematosus (acute, subacute and chronic variants)

2. Dermatomyositis

3. Sjogren syndrome

4. Darier disease

5. Rosacea

6. Melasma

Sometimes:

1. Pemphigus vulgaris

2. Pemphigus foliaceus

3. Atopic dermatitis

4. Seborrhoeic dermatitis

5. Psoriasis

6. Lichen planus (actinicus)

7. Erythema multiforme

8. Mycosis fungoides

Metabolic photodermatoses (rare)

1. Porphyria cutanea tarda

2. Erythropoietic protoporphyria

3. Variegate porphyria

4. Erythropoietic porphyria (Gunther disease)

Genetic photodermatoses (very rare disorders due to genomic instability)

1. Xeroderma pigmentosum

2. Cockayne syndrome

3. Trichothiodystrophy

4. Bloom syndrome

5. Rothmund Thomson syndrome