Extracutaneous manifestations may include arthritis, myalgias, conjunctivitis, and proteinuria. Idiopathic Sweet's syndrome usually occurs in middle-aged women and may follow an upper respiratory infection. An association with malignant disease has been described in about 10 to 15 percent of cases. Myeloproliferative disorders, such as acute myelogenous leukemia, are the most commonly associated malignant disorders, although solid tumors and lymphomas may also occur. Treatment with systemic steroids produces a dramatic improvement in the skin lesions even when they are associated with a malignant disorder.
Untreated lesions resolve over a period of a few weeks to a month or more.
Recurrences are common in patients with associated malignant tumors and may signal a relapse of the cancer. Other therapies reported to be effective in individual cases include the administration of indomethacin, clofazimine, dapsone, colchicine, or potassium iodide. In the evaluation of generalized pruritus, common causes such as drug reaction, xerosis, and scabies must be excluded. If there are no clinically apparent skin diseases, an underlying systemic cause, including malignant disease, must be considered. For example, generalized pruritus may occur in about 13 percent of patients with chronic renal disease and in about 70 to 90 percent of patients undergoing hemodialysis for chronic renal disease.