What are the next steps for an adult patient with a pathology report showing plantar fibromatosis involving peripheral margins except the proximal margin?

Management of Plantar Fibromatosis with Positive Peripheral Margins

Observation with close surveillance is the recommended next step for plantar fibromatosis with positive peripheral margins, as surgical margins do not consistently correlate with recurrence risk in fibromatosis, and immediate re-excision is not indicated unless there is symptomatic progression. 1

Understanding the Evidence on Surgical Margins

The most critical finding from European consensus guidelines is that surgical margins do not consistently correlate with recurrence in fibromatosis 1. Multiple large retrospective series demonstrate this:

• Studies involving 495 patients showed identical 5-year disease-free survival rates (69%) regardless of margin status (M1 vs M2) 1
• Van Broekhoven et al. (132 patients) found no significant difference in recurrence between positive and negative margins (80% vs 85%, p=0.7) 1
• Gronchi et al. (203 patients) showed 5-year disease-free survival of 79% for positive margins versus 82% for negative margins (p=0.5) 1

This evidence fundamentally changes management compared to traditional soft tissue sarcoma approaches 1.

Recommended Management Algorithm

Step 1: Active Surveillance (Primary Recommendation)

• Watchful waiting is now the standard initial approach for fibromatosis, even after incomplete resection 1
• Perform MRI surveillance every 3-6 months for the first 2 years to monitor for progression 1
• Clinical examination should assess for pain, functional impairment, and tumor growth 2
• Spontaneous regression occurs in 20-30% of cases, making observation particularly appropriate 1

Step 2: Intervention Criteria (Only if Surveillance Fails)

Intervene only if the patient develops:

• Progressive symptomatic disease (pain, functional disability) 1, 3
• Documented tumor growth on serial MRI with clinical impact 1
• Significant functional impairment affecting quality of life 2, 4

Step 3: Treatment Options if Intervention Required

Adjuvant Radiotherapy (Preferred for Positive Margins):

• Adjuvant radiotherapy may reduce recurrence risk after incomplete resection, particularly for recurrent tumors 1
• Use IMRT with IGRT techniques at 50-60 Gy in 1.8-2 Gy fractions 1
• Radiation doses of 50-60 Gy for microscopic residual disease are recommended 3
• Post-operative radiation has not demonstrated conclusive benefit after first surgery regardless of margins, but should be considered for recurrent disease 1

Re-excision (Secondary Option):

• Consider only if function can be preserved and patient has symptomatic progression 1
• Wide excision with subtotal plantar fasciectomy if performed 2, 5, 6
• Recurrence rates after partial fasciectomy range from 6-11% in recent series 2
• Delayed wound healing occurs in 52% of cases, with 19% requiring skin grafting, particularly in advanced disease 6

Critical Pitfalls to Avoid

Do Not Perform Immediate Re-excision

• Immediate surgery is no longer the standard treatment for fibromatosis 1
• Re-operation should only occur if adequate margins can be achieved without major morbidity 1
• Function preservation must be prioritized over margin status 1

Plantar Location-Specific Considerations

• Plantar fibromatosis has a 62% control rate overall, with significantly worse outcomes in children 3
• Plantar lesions in young patients represent a high-risk group requiring careful consideration of perioperative radiation 3
• Recurrence rates can reach 60% with aggressive surgical approaches 2, 4
• Major complications include neuroma formation and delayed wound healing requiring skin grafting 5, 6

Radiation Therapy Cautions

• Greater potential for radiation-induced morbidity must be considered, especially in younger patients 3
• Risk-benefit analysis must account for tumor location, patient age, and functional impact 3
• Radiation should be reserved for symptomatic progression or recurrent disease after initial surgery 1, 3

Monitoring Protocol During Observation

• MRI of the surgical site every 3-6 months for first 2-3 years 1
• Document exact size, location, and T2-weighted signal intensity changes 1
• Clinical assessment of pain, function, and quality of life at each visit 2, 4
• Transition to annual imaging after 2-3 years if stable 1

When to Escalate Treatment

Escalate from observation to active treatment only when:

• Progressive disease on serial imaging with clinical symptoms 1
• Functional disability significantly impacting quality of life 2, 4
• Pain refractory to conservative management 2, 4

The key paradigm shift is recognizing that positive margins alone do not mandate immediate intervention in plantar fibromatosis, unlike traditional soft tissue sarcoma management 1.