The acquired hyperostosis syndrome (AHS) (best known synonym: pustulotic arthro-osteitis) is a system disease of the supporting and gliding tissue with sites of predilection characterized by inflammation-induced bony reconstruction of positive balance. This syndrome is affiliated with the seronegative spondylarthropathies. The main finding is the sternocostoclavicular hyperostosis in about 80% of patients. Focal hyperostoses also occur on the skeleton of truncus and extremities and joints. AHS is accompanied by psoriasiform and acneform dermatoses. Overlapping findings with spondylitis ankylosans are reported. Terminology, aetiology, nosology, pathogenesis, histomorphology, clinical and laboratory findings, complications, imaging diagnostic, differential diagnosis and therapy of AHS are discussed. Knowing AHS helps to prevent misdiagnoses (as especially bacterial osteomyelitis, spondylitis, osteoplastic tumor and metastases) and interventional diagnostic procedures.