ABSTRACT
The simple bone cyst, as newly classified by WHO in 2005, is a lesion related to the jawbones. Therefore, it is not a cyst, since it is a cavity devoid of epithelial tissue. It is a rare pathology affecting the mandible more than the maxilla. Its onset occurs mainly during the first two decades of life, irrespective of sex. The purpose of our report is to exhibit the particular case of a 17-year-old male patient whose radiography showed an osteolytic lesion in his right mandibular body. Exploratory surgery and biopsy are performed showing a simple bone cyst. Since then, he is controlled through imaging studies, but presenting an atypical evolution, with its size increasing considerably within a 4-year follow-up. Key words:Case report, simple bone cyst, hemorrhagic bone cyst, solitary bone cyst, idiophatic bone cyst, mandible.