Dark Spot on Skin Graft Post-MOHS Surgery
Initial Assessment and Differential Diagnosis
The dark spot on your skin graft after Mohs surgery most likely represents either residual pigmentation from the graft itself, hemosiderin deposition from post-surgical bleeding, or less commonly, recurrent disease that requires immediate evaluation. You should have this examined by your dermatologic surgeon within 1-2 weeks to rule out recurrence, as early detection is critical for outcomes 1.
Key Clinical Features to Evaluate
Timing of appearance: Dark spots appearing within the first 2-4 weeks post-operatively are more likely benign hemosiderin deposits or graft-related pigmentation, while spots appearing after 3 months warrant higher suspicion for recurrence 1
Location and characteristics: Document whether the spot is within the graft itself, at the graft margins, or in surrounding tissue, as margin recurrence suggests incomplete initial excision 1
Associated symptoms: Pain, tenderness, rapid growth, or ulceration are concerning features that necessitate urgent biopsy 1
Management Algorithm
If the Dark Spot Appears Benign (Hemosiderin/Pigmentation)
Observation with serial photography every 4-6 weeks for the first 6 months is appropriate for stable, asymptomatic pigmentation 1
Dermoscopy evaluation can help differentiate benign pigmentation from concerning features requiring biopsy 1
Most post-surgical hemosiderin deposits resolve spontaneously over 6-12 months without intervention 2
If There is Any Suspicion of Recurrence
Immediate biopsy is mandatory - do not observe suspicious lesions, as delayed diagnosis worsens prognosis 1
Re-excision with Mohs surgery or complete circumferential peripheral and deep margin assessment (CCPDMA) is the gold standard if recurrence is confirmed 1, 3
For recurrent tumors, Mohs surgery demonstrates superior outcomes with 10% recurrence rates compared to 23.3% with standard excision 3
Critical Considerations for Skin Grafts Post-Mohs
Graft-Specific Complications
Partial graft loss occurs in 11-30% of immediate skin grafts, with delayed grafting (12-14 days) showing significantly better survival rates 2
Graft depression and contraction are more common with immediate grafting, particularly on the nasal ala where functional impairment can occur 2
If the dark spot represents graft necrosis or partial loss, granulation tissue formation over 12-14 days followed by repeat grafting yields better outcomes than immediate re-grafting 2
Monitoring Protocol
First follow-up at 2 weeks post-operatively to assess graft take and identify early complications 1, 2
Monthly examinations for 6 months, then every 3 months for 2 years, as most recurrences occur within this timeframe 1
Patient education on self-examination for changes in color, size, texture, or new symptoms is essential 1
Common Pitfalls to Avoid
Do not assume all dark spots are benign pigmentation - when in doubt, biopsy, as missing early recurrence significantly impacts survival 1
Avoid extensive tissue rearrangement or undermining if recurrence is suspected, as this can displace tumor cells and complicate subsequent margin assessment 1
Do not delay histopathologic evaluation of any suspicious changes, as incomplete excision is associated with worse prognosis 1, 3
For high-risk tumors (those requiring Mohs initially), maintain heightened surveillance as these have greater recurrence potential 1, 3