An 8-month-old boy presented with high grade fever of 7 days duration and few reddish lesions on face, scalp and upper limbs (Fig. 1). To start with, there were few lesions on the face that gradually increased in size and number to attain the present status. Drug history, past history and family history were non-contributory except for common cold and mild fever about 10 day prior to onset of cutaneous lesions. Cutaneous examination revealed multiple well-circumscribed erythematous to violaceous papulo-nodules and plaques (few targetoid) over the face, scalp and both upper extremities. Hairs, nails, and mucosa were unaffected; conjunctivae were congested. Laboratory investigations revealed leukocytosis with neutrophilia and raised erythrocyte sedimentation rate. Punch biopsy followed by histopathological examination of a representative lesion from face showed dense perivascular neutrophilic infiltrate along with vasodilatation, nuclear dust and upper dermal edema, without any evidence of vasculitis. A diagnosis of acute febrile neutrophilic dermatosis was made, and prednisolone (1mg/kg/d suspension) was started under antiobiotic cover. Lesions showed improvement at the end of 1st week of treatment.

Fig. 1 Well defined erythematosus to violaceous plaques and nodules on face (A) and flattening of lesions (B) after one week of treatment.

Acute febrile neutrophilic dermatosis, also termed Sweet syndrome (SS), is a reactive process characterized by the abrupt onset of tender, red-to-purple papules, and nodules that coalesce to form plaques. The plaques usually occur on the upper extremities, face, or neck and are typically accompanied by fever and peripheral neutrophilia. SS may be idiopathic or may be associated with infections, inflammatory conditions, malignancy pregnancy, or drugs. Clinical differentials include erythema nodosum leprosum in leprosy patients (presence of features suggestive of leprosy); cellulitis or erysipelas (mostly single lesion, boil prior to the onset of lesion); erythema multiforme (preceding drug history or infection, presence of target lesions); urticaria (transient, itchy) and leukemia cutis. The criteria for diagnosis have been proposed by Su and Liu, and revised by Driesch.