Soft tissue tumors may often be overlooked or mistaken as “simple lesions.” For example, ganglion cysts occur so frequently in the foot and ankle that it has often led to the careless assumption that every asymptomatic, soft, movable mass represents a benign lesion. Unfortunately, this lackadaisical confidence can lead to misdiagnosis and disaster in certain situations.
Although rare, some “simple lesions” may actually represent a malignant process that goes undiagnosed until skeletal metastasis occurs or amputation is required. This tragedy could potentially lead to malpractice litigation for negligent care.
What To Look For In The Initial Presentation
Enzinger and Weiss defined soft tissue tumors as “non-epithelial extraskeletal tissue of the body exclusive of the reticuloendothelial system, glia and supporting tissue of various mesenchymal organs.”1 In light of that definition, soft tissue tumors of the foot and ankle region are relatively common when compared to their osseous counterparts and are more often benign than malignant.2
When a patient comes in with a soft tissue tumor, the first step is to determine whether the lesion is benign or malignant. These patients will initially present with a “bump” on the foot with some report of pain in shoegear or a limp during ambulation. Be aware that most soft tissue neoplasms in the foot and ankle present earlier in their course than tumors at other sites in the body because of the relatively thin soft tissues covering these areas.3
For example, small masses are usually easily palpable in the foot and ankle regions. Dorsal neoplasms often produce symptoms because of pressure from shoegear while plantar lesions are typically aggravated by weightbearing and ambulation forces. Be sure to emphasize a careful history and thorough documentation to determine the duration of symptoms, rate of growth, associated pain, history of trauma or infection. A family history is also essential.
Common clinical symptoms, such as pain, discomfort, tenderness and localized swelling, may be secondary to mechanical obstruction of tightly bound gliding mechanisms of muscles, tendons and ligaments that encompass the foot and ankle areas. However, not all soft tissue neoplasms are painful or small. Statements such as “benign lesions are painless” and “malignant lesions are painful” are grossly inaccurate. Likewise, size is not a predictor of malignancy. A large tumor had to start as a small lesion at one point.4 Fortunately, as stated above, soft tissue tumors of the foot and ankle are much more likely to be benign than their malignant counterparts, soft tissue sarcomas.
A Helpful Primer In Recognizing Ganglion Cysts And Lipomas
Common benign soft tissue tumors one might see in the foot and ankle include ganglion cysts, lipomas, plantar fibromatosis (Ledder hose’s syndrome), hemangiomas and neurilemoma (schwannoma). As far as specific clinical chacteristics go …
• Ganglion cysts are the most common soft tissue tumors in the foot and ankle. They are usually painless lesions of varying size that tend to occur in patients between the ages of 20 and 40. Female patients are three times more likely to develop these cysts.
Aspiration with a large-bore, 18-gauge needle is diagnostic. You’ll note a clear, yellow and viscous fluid. Ganglionic fluid is the product of mucoid degeneration in an area of the joint capsule or tendon sheath. Ganglia may remain stationary, increase in size or spontaneously rupture and disappear. While ganglion cysts can occur at any location in the foot and ankle, they commonly arise from the dorsal surface and are in close opposition to tendons or joints.
• Lipomas may occur in the soft tissue, muscle, tendon sheaths or bone. The mass is soft, non-tender, mobile and usually asymptomatic unless it compresses neural structures. Most lipomas of the foot are slow growing, located in the subcutaneous tissue and are usually solitary. You’ll usually see these lesions along the anteriolateral aspect of the ankle, but they may occur anywhere in the foot and ankle.
Lipomas frequently occur in obese, post-menopausal women and are also common among patients who have hypercholesterolemia.