Introduction to Soft Tissue Tumors of the Foot - Part 1
Soft tissue tumors in the foot a approximately twice as common as bone tumors in the foot. The cause of these lesons may be congenital, infectious, inflammatory, degenerative, or neoplastic conditions. This section will focus on neoplastic tumors as well as lesion that mimic neoplasms. Morton's neuroma, Kaposi's sarcoma, squamous cell carcinoma, and nodular fasciitis will not be covered.
Evaluation of a soft tissue tumor of the foot
One of the most basic management decisions a foot and ankle doctor must make when confronted with a soft tissue mass is to answer the question: "Could this be a cancer?" Not only is this the most pressing question on the patient's mind, but the management of the tumor will be strongly affected by the answer to the question. I recommend that every clinician evaluation a soft tissue tumor in the foot begin with a systematic evaluation of the "cancer risk" associated with the lesion.
The ratio of benign to malignant tumors
Based on published studies of foot tumors, any given soft tissue tumor in the foot has about a 1 in 4 chance of being malignant. Your personal experience is highly dependant on your practice setting and referral base. The ratio of benign to malignant tumors seems to be larger in the foot than in the extremities in general. The reasons for this are uncertain, but the prevalence in the foot of certain malignant tumors and the increased likelihood that a patient with a malignant tumor will seek medical care may be contributory. The most common malignant soft tissue tumors in the foot are synovial sarcoma, clear cell sarcoma, and epithelioid sarcoma.
Quantifying the "cancer risk" of a soft tissue tumor
Certain features of the history and physical exam are strongly associated with benign lesions, whereas other features are indicators of malignant lesions.
| Benign tumors: | Malignant tumors: |
| Are small (< 2-3 cms in the foot) | Are big (> 5 cms) |
| Have been tender all along or variably painful | Are painless or have been painless until just recently |
| Grow and shrink | Grow progressively and never shrink |
| Are superficial | Are deep |
| Are diffuse or have vague borders | Can be felt as a definite mass |
| Are fleshy or soft | Are firm |
| Are mobile | Are fixed |
| Transilluminate | Do not transilluminate |
The authors of this site recommend that any lesion having more than two of the above features that are suggestive of malignancy be treated as malignant until proven benign. Any lesion larger than 5 cms in the foot should also be assumed to be malignant.
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