Amicrobial pustulosis of the folds (APF), also known as amicrobial pustulosis associated with autoimmune disease (APAD), is a rare neutrophilic dermatosis. APF usually occurs in young women and most often is associated with an underlying autoimmune condition. Associated diseases include systemic lupus erythematosus, immune thrombocytopenic purpura, Sjögren syndrome, Hashimoto thyroiditis, and rheumatoid arthritis, among others.

The pustules in APF are sterile, but the lesions can become eroded and secondarily infected. Diagnosis of APF is based largely on clinical presentation and exclusion of other more common diagnoses.

The disease is generally chronic with frequent relapses despite treatment. The disease course of APF does not parallel that of any associated autoimmune disease.