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Sweet’s Syndrome Mimicking Anti-Neutrophil Cytoplasmic Antibodies–Associated Vasculitis

Clinical manifestations. (A) Coalescing infiltrated erythema with tense bullae (arrows) on the left arm. (B) Pustules on the erythematous plaque on the right axilla. (C) Dark-reddish purpuras and infiltrated erythemas with hemorrhagic bullae on the legs. (D) Widespread purpuras and erythemas with highly exudative erosions.

Clinical manifestations. (A) Coalescing infiltrated erythema with tense bullae (arrows) on the left arm. (B) Pustules on the erythematous plaque on the right axilla. (C) Dark-reddish purpuras and infiltrated erythemas with hemorrhagic bullae on the legs. (D) Widespread purpuras and erythemas with highly exudative erosions.

 

Sweet’s syndrome is a rare neutrophilic skin disorder. The antibodies against neutrophil cytoplasmic antigens are called anti-neutrophil cytoplasmic antibodies (ANCAs). Positivity for ANCA has been reported in some nonvasculitic inflammatory disorders, including Sweet’s syndrome.12 Here we report a case of myeloperoxidase (MPO)-ANCA– and (proteinase 3) (PR3)-ANCA–positive Sweet’s syndrome presenting unusual and severe purpuras.

A 41-year-old woman presented with a 3-day history of general malaise, a fever of 39.4°C, and progressive eruptions on the whole body. Examination revealed multiple coalescing erythema and painful erythematous plaques with small pustules distributed on the neck, trunk, and upper limbs (Figure A and B). On the lower limbs, widespread purpuras, tense bullae, and erosions were observed (Figure C and D). No respiratory, gastrointestinal, ocular, neuronal, or articular symptoms were observed. Her white blood cell count was 31,300/µL, with 93% neutrophils. The erythrocyte sedimentation rate, at 23 mm/h, and the C-reactive protein, at 152 mg/L, were elevated. No evidence of infection or malignancy was observed. Serologic tests found MPO-ANCA (68.5 RU/mL; normal range, 0-20 RU/mL) and PR3-ANCA (45.8 RU/mL; normal range, 0-20 RU/mL) to be positive. Antinuclear antibody was negative. The histology of the erythematous plaque with bulla revealed subepidermal blistering due to marked edema of the upper dermis. Dense infiltration of neutrophils, but not eosinophils, was observed in the dermis. No vasculitis or granuloma was present. Immunoglobulin deposition in the vessels was not observed by immunofluorescence studies. The diagnosis of Sweet’s syndrome was made. The fever and the infiltrative erythema disappeared in a few days under systemic prednisone therapy at 1 mg/kg/d. After the treatment the white blood cell count was within normal limits, and the MPO-ANCA and PR3-ANCA titers decreased and finally became negative.

The present case fulfilled the diagnostic criteria of Sweet’s syndrome with respect to both major points: 1) the abrupt onset of tender erythematous plaques; 2) predominant neutrophilic infiltration in the dermis without vasculitis) and with respect to 3 of the 4 minor points: 1) pyrexia > 38°C; 2) laboratory abnormalities [elevated erythrocyte sedimentation rate, positive C-reactive protein, leukocytosis, and a left shift of white blood cells]; 3) an excellent response to systemic corticosteroid therapy.34 Widespread purpura in “classic” Sweet’s syndrome has not been reported; however, giant cellulitis-like Sweet’s syndrome, a rare subtype of Sweet’s syndrome, is characterized by indurated erythematous plaques with a vesicular, bullous, hemorrhagic appearance.5Widespread purpura suggests the presence of severe nonvasculitic endothelial damage from massive neutrophilic infiltration; therefore, the excess neutrophilic activation in this case may have contributed to the ANCA induction, as well as severe clinical appearance mimicking ANCA-associated vasculitis.

In conclusion, we present a case of Sweet’s syndrome that showed various severe skin symptoms and serologic positivity for both MPO-ANCA and PR3-ANCA. Clinicians should be aware of the occurrence of these striking purpuras in patients with Sweet’s syndrome.

 

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-Hideyuki Kosumi, MD, Mika Watanabe, MD, PhD, Ken Natsuga, MD, PhD’Correspondence information about the author MD, PhD Ken Natsuga, Toshinari Miyauchi, MD, Chihiro Shiiya, MD, Hideyuki Ujiie, MD, PhD, Hiroshi Shimizu, MD, PhD

This article originally appeared in the June issue  of The American Journal of Medicine.

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