The co-existence of a non-ossifying fibroma and a cortical desmoid in this patient serves to highlight the differences between these two benign lesions. The characteristic location of the cortical desmoid, on the dorsomedial aspect of the distal femur (the attachment of the adductor magnus or medial head of gastrocnemius) is also well illustrated in this patient. The age and the incidental detection (asymptomatic) of the lesion are also typical.