Internal Medicine

0521779407-17 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:57

1172 Phosphate Deficiency Photosensitivity

follow-up

■Monitor serum phosphate, creatinine, calcium to avoid hypocal-

cemia, hyperphosphatemia, hypotension

complications and prognosis

n/a

PHOTOSENSITIVITY

JEFFREY P. CALLEN, MD

history & physical

History

■Eruption on exposed surfaces, patient may note the relationship to

the exposure.

■Classification:

➣Phototoxicity – increased reaction to sun or UVB light commonly

caused by drugs, particularly sulfonamides, thiazide diuretics,

and tetracyclines

➣Photoallergy – cell-mediated response that requires both a

drug/antigen and light, most often UVA light. Most common:

fragrances and sunscreens containing PABA or PABA esters

➣Endogenous diseases – polymorphous light eruption (PMLE)

and lupus erythematosus (LE) are the most common, porphyria

cutanea tarda (PCT) and pseudoporphyria are less common

PMLE – often occurs with intense exposure or early in the

spring/summer and lessens in its severity toward fall even with

continued exposure (hardening). It is often extremely pruritic.

LE – patients may have accompanying systemic complaints

(see chapter on Cutaneous LE)

PCT/Pseudoporphyria may complain of fragility of the skin

PCT often associated with Hepatitis C infection

Pseudoporphyria is caused by drugs (particularly the

NSAIDs naproxen, nabumetone and oxaprozin), tanning

beds, and is associated with hemodialysis

➣Photoaggravated Diseases

Acne vulgaris

Darier’s disease (keratosis follicularis)

Dermatomyositis

Grover’s disease (transient acantholytic dermatosis)

Herpes simplex