Can You Have a Cyst on the Medial Aspect of Your Ankle?
Yes, cysts can absolutely occur on the medial aspect of the ankle, though they are uncommon in this location. Several types of cystic lesions have been documented in the medical literature affecting the medial ankle region, including ganglion cysts, bone cysts, and other soft tissue masses 1, 2.
Types of Cysts That Can Occur Medially at the Ankle
Ganglion Cysts
- Ganglion cysts are the most common soft tissue cystic masses and can arise around the ankle, though they more typically occur on the dorsal (top) aspect of the foot and ankle rather than medially 3.
- These cysts represent fluid-filled sacs that develop from joint capsules or tendon sheaths 4.
- When present medially, they may arise from the tibialis posterior tendon sheath or adjacent joint structures 5.
Bone Cysts (Unicameral Bone Cysts)
- Unicameral bone cysts can occur in the medial malleolus (the bony prominence on the inner ankle), though this is rare 1.
- These are fluid-filled cavities within the bone itself that may cause continuous pain and require surgical intervention 1.
Other Cystic Lesions
- Glomus tumors with cystic changes have been documented on both the medial and lateral aspects of the ankle, though these are extremely uncommon 2.
- Subchondral cysts can develop in the context of degenerative joint disease affecting the ankle 5.
Clinical Presentation and Diagnosis
When to Suspect a Medial Ankle Cyst
- Palpable swelling or mass on the inner aspect of the ankle 5.
- Pain that may be continuous (as with bone cysts) or positional 1.
- Tenderness over the affected area 5.
- Possible limitation of ankle motion depending on size and location 6.
Diagnostic Approach
Start with plain radiographs of the ankle to evaluate for underlying bone pathology, joint disease, or calcifications that might suggest the nature of the cystic lesion 5.
Ultrasound is the preferred next step for confirming soft tissue cystic masses, as it can:
- Accurately identify fluid-filled structures 5
- Determine the vascularity of the mass to help differentiate benign from potentially concerning lesions 5
- Guide aspiration if needed 5
MRI without contrast should be obtained when:
- The diagnosis remains unclear after ultrasound 5
- There is concern for bone involvement or osteochondral pathology 5
- Surgical planning is being considered 5
- You need to evaluate associated soft tissue structures like tendons and ligaments 5
Important Clinical Pitfalls
Don't Assume All Masses Are Benign
- Not all palpable masses around the ankle are simple cysts—imaging is essential to exclude other pathology 6.
- Atypical features on imaging should prompt consideration of alternative diagnoses including tumors 5, 2.
Consider the Clinical Context
- In patients with chronic ankle pain and degenerative changes, subchondral cysts may be present as part of the osteoarthritic process 5.
- Inflammatory conditions affecting the ankle joint can lead to tenosynovitis and associated cystic changes 5.
- The medial ankle region includes the tibialis posterior tendon, which can develop tenosynovitis detectable by ultrasound 5.
Location Matters for Differential Diagnosis
While the evidence primarily discusses popliteal (Baker's) cysts behind the knee 6, 7, the principles of cyst evaluation apply to ankle cysts—always confirm the diagnosis with imaging rather than relying on clinical examination alone 5.