Adult Still's disease presenting as serum sickness

A 30‐year‐old Chinese woman presented with fever of 104 °F, diffuse arthralgias, multiple pruritic erythematous papules and plaques, and pharyngitis. Three weeks prior to admission, she had received empirically a single intramuscuiar injection of penicillin for the pharyngitis. Several days later, fever, arthraigias, and an eruption were observed. The patient was started on oral prednisone, 40 mg daily, and tapered to 15 mg daily during a 21‐day period. The persistence of these findings led to subsequent hospitalization. On physical examination, the patient appeared acutely ill, with fever of 102.5 °F and multiple annular and polycyclic urticarial plaques, ranging from 0.5 to 3.0 cm in diameter, symmetrically located on the neck, upper part of the back, upper aspect of the chest, and flexural aspect of the forearms and arms (Fig. 1). There was evidence of asymmetric arthritis involving the wrists, knees, and elbows. Abnormal laboratory tests on admission included a white cell count of 21.1 × 10 3 /mm 3 with 94.8% granulocytes, normochromic normocytic anemia with hemoglobin of 10.0 g/dL, an erythrocyte sedimentation rate of 115 mm/h, lactate dehydrogenase of 373 units/mL (normal: 100–225 units/mL), and a serum iron of 32 μmol/L (normal: 50–150 μg/dL). At this juncture, a clinical diagnosis of serum sickness induced by penicillin was considered most likely. Despite the continuation of prednisone, 15 mg daily, spiking fevers, skin lesions, and joint symptoms persisted for 2 weeks. Additional studies did not reveal infection, collagen vascular disease, or malignancy; these included repeated blood cultures, antistreptolysin O titer (ASLO), rapid plasma reagin (RPR), serologic analysis for hepatitis virus, Lyme disease, Mycoplasma pneumoniae , cytomegalovirus, and parvovirus, as well as complement factors, rheumatoid factor, antinuclear antibody, sequential chest X‐rays, total body gallium scan, conventional electrocardiograms, and a transthoracic echocardiogram. An abdominal sonogram showed mild splenomegaly with a normal‐sized liver. A serum ferritin level was profoundly elevated at 20,440 μg/L (normal: 15–200 μg/L). A skin biopsy specimen obtained from an urticarial plaque on the arm showed a mild superficial perivascular lymphocytic infiltrate with occasional neutrophils. There were no features of vasculitis. The epidermis was intact (Figs 2 and 3). A diagnosis of adult Still's disease (ASD) was ultimately based upon the absence of diagnostic markers in the blood and tissue for infection, collagen vascular disease, and malignancy, in conjunction with exceptionally high serum levels of ferritin. Aspirin was started at 3.9 g daily and oral prednisone was maintained at 15 mg daily. Two weeks later, the patient was afebrile with complete resolution of the cutaneous findings. Two months after discharge, the patient was symptom‐free with the exception of mild arthralgias involving both knees. A repeated ferritin level was 460 μg/L. The white cell count remained elevated at 15.1 × 10 3 /mm 3 , presumably as a consequence of corticosteroid therapy.