What is the appropriate treatment for an elderly female patient presenting with a knot on her leg?

Immediate Evaluation for a Palpable Leg Mass in an Elderly Female

Perform an urgent duplex ultrasound examination to exclude a popliteal artery aneurysm, as this represents a potentially limb-threatening condition that requires immediate surgical evaluation if confirmed. 1

Initial Diagnostic Approach

Critical First Step: Rule Out Vascular Aneurysm

• Any palpable mass in the popliteal region (behind the knee) or leg requires immediate ultrasound imaging to distinguish a potentially dangerous arterial aneurysm from benign conditions like Baker's cysts or soft tissue masses 1
• Popliteal artery aneurysms ≥2.0 cm in diameter carry significant risk of thrombosis, limb-threatening ischemia, and potential amputation if left untreated 1
• The presence of a prominent popliteal pulse in the opposite leg may provide a valuable diagnostic clue, as 50% of popliteal aneurysms are bilateral 1

Physical Examination Priorities

• Palpate all leg pulses bilaterally (femoral, popliteal, dorsalis pedis, posterior tibial) to assess vascular status 1
• Examine for signs of peripheral ischemia: dependent rubor, pallor with elevation, absence of hair growth, dystrophic toenails 1
• Assess for signs of venous insufficiency: chronic edema, skin pigmentation changes, varicosities 2, 3
• Check for warmth, erythema, or tenderness suggesting infection or thrombosis 1

Differential Diagnosis by Location and Characteristics

If Mass is in Popliteal Fossa (Behind Knee)

• Popliteal artery aneurysm: Requires urgent surgical referral if ≥2.0 cm; thrombosis occurs in 39% of cases and can cause catastrophic limb loss 1, 4
• Baker's cyst (synovial cyst): Benign, but ultrasound needed to differentiate from aneurysm 1
• Popliteal artery entrapment syndrome: Consider if patient has exercise-induced symptoms; requires MR angiography for confirmation 4

If Mass is Elsewhere on Leg

• Deep vein thrombosis with superficial extension: Presents as tender, warm, swollen area; requires urgent evaluation with duplex ultrasound and D-dimer if clinical suspicion is moderate-to-high 1
• Soft tissue abscess or infection: Requires incision and drainage if fluctuant, with culture-directed antibiotics 1
• Lipoma or other benign soft tissue mass: Can be observed if asymptomatic and non-vascular on imaging 5

Management Algorithm

For Confirmed Popliteal Artery Aneurysm

1. Immediate surgical consultation for aneurysms ≥2.0 cm in diameter 1
2. If acute thrombosis with poor distal flow: perform catheter-directed thrombolysis or mechanical thrombectomy before definitive repair to restore runoff vessels 1, 4
3. Surgical repair (bypass grafting) should be performed urgently to prevent limb loss; 10-year limb salvage rates exceed 90% when done electively 1
4. Postoperative antiplatelet therapy indefinitely 4

For Suspected DVT

• Calculate Wells score and obtain D-dimer if score indicates moderate probability 1
• Perform compression ultrasound of entire leg; if positive for proximal (above-knee) DVT, initiate anticoagulation immediately 1
• For isolated below-knee DVT, either anticoagulate or perform serial imaging at 1 week to exclude proximal extension 1

For Non-Vascular Masses

• If soft tissue infection suspected: obtain cultures, initiate empiric antibiotics, consider surgical drainage 1
• If benign mass suspected after vascular pathology excluded: can observe or refer to appropriate specialist based on characteristics 5, 6

Critical Pitfalls to Avoid

• Never dismiss a palpable popliteal mass without ultrasound imaging—small aneurysms (even <2 cm) can thrombose and cause limb loss, with complications occurring in 6.5% of observed cases 1
• Do not assume bilateral leg swelling is simply "edema" without evaluating for systemic causes (heart failure, venous insufficiency, medications) or bilateral vascular pathology 2, 3
• In elderly patients with diabetes and peripheral neuropathy, symptoms may be atypical or absent despite significant vascular disease 1
• Measure ankle-brachial index if peripheral arterial disease suspected; values <0.5 indicate critical limb ischemia requiring urgent vascular intervention 1