Distal Irregularities of the Femur Simulating Malignancy

Knee Lesion in a 62-year-old Woman

“…Some [21] consider it a developmental anomaly while others consider it an earlier phase of the more common fibrocortical defect [4,7]. Most lesions can be related to chronic traction or avulsive injury at the insertion of the extensor aspect of the adductor magus [2,5,9,14,20] or to the origin of the medial head of the gastrocnemius [7,17,20,23,26] and plantaris muscles [7]. Some authors, however, have not found tendinous attachments at this location [4,21,27].…”

MR findings of avulsive cortical irregularity of the distal femur

“…This condition is found only among children and adolescents, and is located at the posteromedial aspect of the distal femoral metaphysis; it is more common in males than females [3,8,10,12]. The exact etiology is not yet known.…”

“…The exact etiology is not yet known. Some consider it to be identical to fibrous cortical defect [7], while others believe it to be brought on as a result of stress at the attachment of the tendon of the adductor magnus muscle [2] or the medial head of the gastrocnemius muscle [4,6,8,10,11]. Resnick and Greenway reviewed the previous reports and divided them into two categories [9].…”

“…The pathogenesis of this condition is not yet known; some consider it to be identical to fibrous cortical defect [7], while others believe it to be a result of stress at the tendinous attachment of skeletal muscle [l, 2, 4, 6, 8-11]. This bony change occurs only in children and adolescents; it has a predilection for males [3,8,10,12], and clinically may simulate malignancy not only radiologically but also microscopically [6, 7, 10, I 1, 13]. It has been described as asymptomatic [6, 1 l, Correspondence to: T. Yamazaki, Department of Radiology, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aobaku, Sendai 980, Japan 12].…”

Femur

“…Although usually benign in appearance, these radiologically apparent cortical erosions are sometimes suggestive of destructive or infiltrative lesions such as osteomyelitis or osteogenic sarcoma. [1][2][3]14,15,17,20 The distal femoral metaphyseal "lesion" is almost exclusively located on the posteromedial aspect of the femoral condyle, above the adductor tubercle ( Fig. 21-7).…”