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.

Dermatomyositis

Diagnostic criteria:
1) Proximal muscle weakness (shoulders, pelvic girdle muscles)
2) Increased CK
3) Myopathic changes on EMG
4) Muscle biopsy showing inflammation
5) Dermatologic involvement as outlined below

#5 + 3 others: Definite
#5 + 2 others: Probable
#5 + 1 other: Possible

Presentation:
Usually insidious onset of proximal weakness affecting shoulders, pelvic girdle. Neck flexor weakness also prominent. Dysphagia/dysphonia may occur. Synovitis is rare.
Pulmonary involvement with fibrosis/pneumonitis may occur. Cardiac involvement (myocarditis) occurs, but is relatively uncommon

Dermatologic findings:
Gottron's papules are lacy, pink/violaceous, raised or macular, and symmetric over dorsal IP jts, elbows, knees.
Heliotrope rash is violaceous discolouration of lids with periorbital edema.
Erythema of shoulders/neck (Shawl sign) or neck/chest (V-sign)- shown above
Periungal telangiectasias, nail changes (cuticular hypertrophy)
Raynaud's may be present
Mechanic's hands- coarse, fissured, scaly, hyperkeratotic hands

Investigations:
CK is increased during disease course, but not necessarily early. ASL/ALT/LDH may all be increased. ESR is >50 in 20%, normal in 50%.
EMG shows characteristic (but not pathognemonic) changes. Bx shows focal infiltration, CD8 T cells

Therapy usually consists of steroids, and possible addition of steroid-sparing agents such as methotrexate or azathioprine.

Malignancy association:
20-30% of patients have an underlying malignancy; dermatomyositis may pre-date the malignancy as in other paraneoplastic syndromes
It is controversial how aggressively to search for malignancy, and there is little high quality evidence to guide.
At the very least, everyone should get age-appropriate screening. Many experts would also measure tumor marker levels, and consider additional screening such as thoracic or abdominal imaging.

Link:
Click here for a good online review of dermatomyositis from American Family Physician