Concurrent Sweet's syndrome and acute sarcoidosis (Löfgren's syndrome) has been reported in 4 cases. We describe a 40-year-old woman with biopsy confirmed lesions of Sweet's syndrome and erythema nodosum together with arthritis and hilar and mediastinal adenopathy. We review the association of Sweet's syndrome and malignancy or hematologic disorders, and the need to exclude malignancy when hilar adenopathy is found. Aggressive diagnostic procedures can be avoided with prompt recognition of Löfgren's syndrome.