Concurrent occurrence of Sweet's syndrome and erythema nodosum: an overlap in the spectrum of reactive dermatoses.

Simultaneous occurrence of Sweet's syndrome and erythema nodosum is very rare. We describe a case of a young male with a recent history of streptococcal infection who presented with concurrent Sweet's syndrome and erythema nodosum. Although the exact pathogenesis of these dermatoses is not yet clear, their similarities and simultaneous occurrence suggest a possible common underlying mechanism and may represent a continuum of reactive dermatoses. Evaluation of the role of cytokines in the etiopathogenesis of these conditions will be useful for further assessment and treatment of these conditions. Like the association of acanthosis nigricans and certain cancers and diabetes, Sweet's syndrome and erythema nodosum may be associated with certain malignancies, autoimmune disorders, or inflammatory bowel disease. Early recognition of these skin lesions can guide a search for underlying disorders. Patients with Sweet's syndrome should undergo an age-appropriate work-up for malignancy.