[Aneurysmal cyst of the pelvis. Apropos of a case].

The authors present an aneurysmal bone cyst of the pelvis which was unusual in its radiographic aspects. Its aggressive features made it difficult to distinguish from a malignant lesion. We develop the imaging methods contribution in positive and differential diagnosis and underline the modern methods interest (CT scan, MR imaging). Biopsy is necessary to confirm the diagnosis and recognize possible causal malignant tumor.