What is the best course of treatment for a 62-year-old female patient with malignant melanoma of the left lower limb, experiencing pain and swelling due to fluid reaccumulation after undergoing wide local excision, sentinel lymph node biopsy, and sclerotherapy, and currently on pembrolizumab (pembrolizumab) and having completed a course of antibiotics?

Management of Recurrent Seroma in Post-Surgical Melanoma Patient on Pembrolizumab

Continue conservative management with compression, elevation, and symptomatic pain control rather than proceeding with repeat sclerotherapy, as the patient is at significantly increased infection risk from pembrolizumab-induced immunosuppression, and the current clinical examination shows no signs of infection with appropriate wound healing. 1

Critical Safety Concerns with Pembrolizumab and Invasive Procedures

The primary concern in this case is the substantially elevated infection risk associated with pembrolizumab therapy:

• Pembrolizumab significantly increases susceptibility to severe infections, particularly tuberculosis and other bacterial infections, as PD-1 blockade impairs normal immune responses to pathogens 1
• Repeated invasive procedures create additional portals for bacterial entry in immunotherapy patients, which is particularly dangerous given this patient's immunocompromised state 1
• The patient has already undergone multiple aspirations (twice in office, once with IR-guided sclerotherapy), and has had one episode of possible infection requiring antibiotics 1

Current Clinical Status Supports Conservative Management

The physical examination findings are reassuring and argue against aggressive intervention:

• Incision is "well-approximated, c/d/l" indicating appropriate healing despite the seroma 1
• "No significant erythema or palpable warmth" on examination, which supports continued conservative management rather than invasive procedures 1
• The patient's pain is likely related to tissue tension from fluid reaccumulation rather than infection, given the benign examination findings 1

Recommended Management Algorithm

Immediate Management (Next 1-2 Weeks)

• Continue current compression wraps and leg elevation as already prescribed 1
• Ice or heat application for 20 minutes for symptomatic relief as currently being done 1
• Analgesics (acetaminophen or NSAIDs if not contraindicated) for pain management 1
• Weekly monitoring for volume changes, signs of infection, and patient comfort rather than scheduling routine repeat sclerotherapy 1

Surveillance Parameters

Close surveillance for signs of infection is mandatory in this immunotherapy patient 1:

• Erythema
• Warmth
• Purulent drainage
• Fever
• Systemic symptoms

Any of these findings should prompt immediate evaluation and consideration of antibiotics 1

When to Consider Repeat Aspiration

Avoid unnecessary invasive procedures that create additional portals for bacterial entry 1. Only consider repeat aspiration if:

• Seroma causes significant functional impairment
• Evidence of infection develops requiring drainage
• Conservative measures fail after 4-6 weeks and seroma is enlarging

Rationale for Avoiding Routine Repeat Sclerotherapy

While the insurance determination cites lack of evidence for sclerotherapy in seromas, the more pressing clinical concern is infection risk in an immunocompromised patient:

• The patient is on pembrolizumab, which has demonstrated significant efficacy in melanoma (hazard ratio 0.61 for recurrence-free survival in stage IIB/IIC disease) 2
• Pembrolizumab-related immune suppression creates ongoing risk with extended administration 3
• The melanoma treatment must take priority, and avoiding complications that could interrupt pembrolizumab therapy is paramount 1

Melanoma Treatment Considerations

The patient's melanoma management is appropriate:

• Pembrolizumab is the standard adjuvant therapy for high-risk melanoma and has shown superior outcomes compared to placebo 2
• The patient has completed antibiotics and is continuing pembrolizumab as planned 1
• Proper management of local complications like seroma is essential to ensure optimal outcomes, particularly when patients are receiving systemic treatments like pembrolizumab 1

Common Pitfalls to Avoid

• Do not perform routine repeat sclerotherapy at 7-10 days as initially planned—this creates unnecessary infection risk 1
• Do not dismiss the significance of pembrolizumab-induced immunosuppression when considering invasive procedures 1
• Do not delay evaluation if any signs of infection develop, as immunotherapy patients can deteriorate rapidly 1
• Do not interrupt pembrolizumab therapy unnecessarily, as this could compromise melanoma outcomes 2