This learning module explains how to assess the potential for malignancy in bone tumors of the foot.
This learning module describes the different types of lesions, how to identify them on a radiograph, and what each means in terms of malignancy.
The malignant potential of bone tumors can be reliably determined by careful analysis of their appearance on plain radiographs. Bone tumors are be described as latent, active, or aggressive based on analysis of the tumor margins, the zone of transition, the presence and extent of periosteal reaction, and any permeation or extension into nearby structures.
Latent lesions exhibit little or no growth and often exhibit a well developed sclerotic rim at their margins. There is no periosteal reaction, no soft tissue extension, and the zone of transition is very narrow, typically 1 mm or less.
Active lesions exhibit gradual growth with progressive local destruction of bone, no sclerotic rim or a partial rim, no or mild periosteal reaction, a zone of transition of one to a few millimeters wide, and some tendency to thin or destroy the cortex and expand the bone, but no soft tissue mass.
Aggressive lesions exhibit rapid growth with complete destruction of nearby bone, permeation of the bone or moth-eaten destruction of the bone, a prominent periosteal reaction, a wide zone of transition of several millimeters or more, permeation or extension into the soft tissues, or a soft tissue mass.
In the foot, these changes are more difficult to appreciate, because the bones are small and close together.
Lesions that are latent may require no treatment, and in many cases biopsy is not necessary. Active lesions typically require complete local removal based on the results of of a preliminary biopsy. Aggressive lesions are best managed with prompt referral to an orthopedic oncologist, where a complete systemic cancer workup and biopsy will be necessary.
