Skeletal Radiol (1998) 27:330±333  International Skeletal Society 1998 ARTICLE P. Carpintero A. García-Frasquet E. Tarradas C. Logroæo A. Carrascal A. Carreto Bone island and leprosy P. Carpintero ( ) ) ´ A. García-Frasquet Department of Orthopaedic Surgery, Córdoba University, Medical School, Reina Sofia University Hospital, Córdoba, Spain E. Tarradas Department of Imaging, Córdoba University, Medical School, Córdoba, Spain C. Logroæo Department of Dermatology, Reina Sofia University Hospital, Córdoba, Spain A. Carrascal Department of Radiology, Infanta Elena Hospital, Huelva, Spain A. Carreto Department of Radiology, Reina Sofia University Hospital, Córdoba, Spain Abstract Objective. To determine the incidence of bone islands in lep- rosy patients. Design. X-rays of feet and hands of patients with Hansen's disease (lep- rosy) were reviewed retrospectively. A second group of related age- and sex-matched patients who did not have Hansen's disease was used for control purposes. Controls had un- dergone hand or foot X-rays during diagnosis of other pathologies. The patients with Hansen's disease were compared with the control group, and were also analyzed as subgroups with different types of leprosy. The results were subjected to statistical analysis. Patients. Ninety patients with Han- sen's disease were randomly selected for this study. Patients who had had ulcers on hands or feet were excluded from the study. Results and conclusions. Bone is- lands were demonstrated in 20 pa- tients with Hansen's disease; no bone islands were observed in the controls. This was statistically significant (P<0.01). Bone islands were only seen in patients with lepromatous leprosy and borderline types but were not demonstrated in patients with tu- berculoid leprosy. There was also a statistically significant relationship for a disease duration of 15 years or more. The cause of this raised inci- dence of enostosis in leprosy patients is not clear, but there may be a ge- netic predisposition in patients with leprosy, or it may be a side effect of leprosy, especially the lepromatous form. Key words Enostosis ´ Bone island ´ Leprosy ´ Bone involvement Introduction Leprosy, or Hansen's disease, is a chronic granulomatous disease which is still prevalent in some areas [1]. In the course of the disease, lesions may appear in the skeleton of affected patients, usually involving the hand and foot [2]. These lesions are produced by two fundamental mechanisms: the first is as a direct consequence of bone colonization by Hansen's bacillus (leprous osteitis and specific periostitis), while the second is indirect, in that bone lesions are secondary to involvement of the periph- eral nervous system (bone resorption, osteomyelitis, and destructive joint changes or ªCharcot jointº) [3]. The present authors, however, have also observed en- ostosis or the formation of ªbone islandsº relatively fre- quently on radiographs of patients with Hansen's disease and undertook this study to asses this particular bone le- sion in Hansen's disease. No references to this feature have been found in the literature. Patients and methods A retrospective study was undertaken of 90 randomly selected pa- tients with Hansen's disease. Hand and foot radiographs of these pa- tients were analyzed (720 X-rays; two projections for each hand and foot) in order to determine the frequency, location, symptoms and characteristic features with particular reference to enostosis. Previ- ous radiographs going back over 5 years were studied for a number of patients, six of whom displayed bone islands. Other parameters studied included the type of leprosy (lepromatous, tuberculoid, or