Sweet syndrome associated with new-onset systemic lupus erythematosus in a 25-year-old man

Neutrophilic skin lesions in autoimmune connective tissue diseases: nine cases and a literature review

The pathophysiology of neutrophilic dermatoses (NDs) and autoimmune connective tissue diseases (AICTDs) is incompletely understood. The association between NDs and AICTDs is rare; recently, however, a distinctive subset of cutaneous lupus erythematosus (LE, the prototypical AICTD) with neutrophilic histological features has been proposed to be included in the spectrum of lupus. The aim of our study was to test the validity of such a classification. We conducted a monocentric retrospective study of 7028 AICTDs patients. Among these 7028 patients, a skin biopsy was performed in 932 cases with mainly neutrophilic infiltrate on histology in 9 cases. Combining our 9 cases and an exhaustive literature review, pyoderma gangrenosum, Sweet syndrome (n = 49), Sweet-like ND (n = 13), neutrophilic urticarial dermatosis (n = 6), palisaded neutrophilic granulomatous dermatitis (n = 12), and histiocytoid neutrophilic dermatitis (n = 2) were likely to occur both in AICTDs and autoinflammatory diseases. Other NDs were specifically encountered in AICTDs: bullous LE (n = 71), amicrobial pustulosis of the folds (n = 28), autoimmunity-related ND (n = 24), ND resembling erythema gyratum repens (n = 1), and neutrophilic annular erythema (n = 1). The improvement of AICTDS neutrophilic lesions under neutrophil targeting therapy suggests possible common physiopathological pathways between NDs and AICTDs.

Association of Sweet's Syndrome and Systemic Lupus Erythematosus

Sweet's syndrome is an acute febrile neutrophilic dermatosis which usually presents as an idiopathic disorder but can also be drug induced, associated with hematopoetic malignancies and myelodysplastic disorders, and more, infrequently, observed in autoimmune disorders. Sweet's syndrome has been reported in three cases of neonatal lupus, three cases of hydralazine-induced lupus in adults, and in nine pediatric and adult systemic lupus erythematosus (SLE) patients. We describe three additional adult cases of Sweet's associated with SLE and provide a focused review on nondrug-induced, nonneonatal SLE and Sweet's. In two of three new cases, as in the majority of prior cases, the skin rash of Sweet's paralleled underlying SLE disease activity. The pathogenesis of Sweet's remains elusive, but evidence suggests that cytokine dysregulation may be central to the clinical and pathological changes in this condition, as well as in SLE. Further research is needed to define the exact relationship between the two conditions.