Introduction : L’atteinte osseuse par le lymphome survient généralement dans le cadre d’une maladie systémique généralisée. L’atteinte lymphomateuse primitive de l’os est une entité rare qui représente 3 à 7% des tumeurs osseuses malignes primitives et moins de 2% de l’ensemble des lymphomes. Les formes multifocales sont encore plus rares et peuvent se confondre avec des métastases osseuses. Le diagnostic positif est orienté par la clinique et la radiologie, mais seule l’histologie le confirme. Observation : Nous rapportons un cas rare d’un lymphome iliaque primitif chez un homme âgé de 58 ans. L’étude histologique a confirmé le diagnostic d’un lymphome B diffus à grandes cellules. Une tomographie par émission monophotonique couplée à la tomodensitométrie (TEP/TDM) au 18 fluorodésoxyglucose (FDG) pratiquée dans le cadre du bilan d’extension a mis en évidence une atteinte osseuse multifocale. Conclusion : Ce cas met en évidence l’importance de penser au diagnostic du lymphome osseux primitif, même s’il se présente dans un site inhabituel, ainsi que la valeur de l’imagerie métabolique pour évaluer l’étendue de la maladie.

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