Fever and rash, Sweet's syndrome

Today we discused an approach to the patient presenting with fever and rash, some of the causes of a diffuse erythematous rash (i.e. erythroderma), and the more specific entity of "Sweet's syndrome"

Fever and rash- a broad differential needs to be considered, some of which are life-threatening and require immediate attention.

One possible way to approach this is by the type of rash involved, then subdivide by etiology (not intended to be complete):

Petechiae/purpura
Infections: Bacteremias (esp. meningoccemia, endocarditis), viral, rickettsial diseases.
Drug reactions (esp. septra, NSAIDs, b-lactam antibiotics)
Inflammatory: Vasculitis, autoimmune conditions (SLE, cryoglobulinemia, sjogren's, RA, many others)

Vescicular/bullous
Infections: Disseminated herpes zoster, disseminated herpes simplex
Drug reactions (Stevens Johnson, toxic epidermal necrolysis)

Macules/papules
Viral exanthem (think of parvo, HIV, HCV, EBV, others)
Syphillis (secondary); esp. hands and feet
Drug reaction (erythema multiforme, others)
Neoplastic: if fever-associated, hematologic malignancy more likely


Erythroderma- defined as 90% of body surface involved with erythema, swelling, scale. This narrows the differential somewhat; major causes include
Psoriasis
Cutaneous T-cell lymphoma
Sweet's syndrome
Drugs (esp. anticonvulsants, allopurinol, hydralazine)
Toxic shock syndrome

Sweet syndrome (shown above)- acute neutrophilic dermatosis
Papules coalescing into plaques. Erythematous, tender, on face, back, arms. May see fever, arthritis, conjunctivitis. 10% of these pts have malignancy, often AML. Other associations include infections (esp viral), autoimmune conditions, drugs.

Treatment usually includes steroids.