Internal Medicine

P1: RLJ/OZN P2: KUF

0521779407-D-01 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:41

506 Drug Eruptions

tests

■Skin Biopsy+histopathology – more useful and important if skin

changes pustular, blistering, purpuric or erythrodermic, or diagnosis

uncertain. Do immunofluorescence in blistering eruptions.

■If severe or possible internal organ involvement:

➣CBC – looking for neutrophilia, atypical lymphocytosis, eosino-

philia, cytopenias (platelets, RBCs, WBCs), hemolytic anemia

➣LFTs (looking for hepatitis)

➣Urea, creatinine and urine analysis (looking for nephritis)

➣Investigate other symptomatic organs as needed – e.g., CXR, LP

differential diagnosis

■Depends on reaction morphology

■Exanthematous – infections (viral, bacterial, rickettsial), collagen

vascular disease, miliaria

■Dermatitic– see Dermatitis chapter

■Uriticarial– see Urticaria chapter

■Pustular– pustular psoriasis, folliculitits, steroid acne

■Erythrodermic– Eczema, psoriasis, seborrheic dermatitis, lym-

phoma, mycosis fungoides, idiopathic, pityriasis rubra pilaris, hy-

pereosinophilic syndrome

■Blistering– bullous pemphigoid, pemphigus, other immune-

mediated blistering disorders

■Purpuric– vasculitis, coagulopathy

More Common Drug Associations

■Exanthematous– antibiotics, antiepileptics, gold

■Dermatitic– gold, beta-blockers, “statins”, tricyclic antidepressants

■AGEP– macrolide antibiotics, penicillins, cephalosporins, calcium

antagonists, terbinafine, itraconazole, Chinese herbal remedies

■Toxic Epidermal Necrolysis(and Stevens-Johnson syndrome) – sul-

fonamide antibiotics, phenytoin, phenobarbital, carbamazepine,

lamotrigine, NSAIDs, allopurinol, quinolones, Chinese herbal reme-

dies

■Internal organ involvement– Phenytoin, phenobarbital, carba-

mazepine, lamotrigine, sulfonamide antibiotics, dapsone, allopuri-

nol, minocycline, metronidazole, trimethoprim, abacavir

■Fixed Drug Eruption– Acetaminophen, sulfonamide antibiotics,

tetracyclines, phenobarbital, phenolphthalein

■Erythroderma– Gold, penicillin, phenytoin, phenobarbital, carba-

mazepine, lamotrigine, allopurinol