External Medicine
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Merkel Cell Carcinoma
ETIOLOGY
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Although risk factors may be overlapping, UVR is the leading cause, found to be responsible in 65.1% of cases. Immunosuppression was considered the main causal factor in only 2.5% of cases. MCPyV is present in 63.8% of cases. 39602110
TREATMENT
Surgical Management
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Current NCCN guidelines recommend either WLE, MMS, or surgery with PDEMA for the primary site. Narrow margin excision is also endorsed in some cases where radiotherapy will be used adjunctively.
Mohs vs WLE
Overall Survival After Mohs Surgery for Early-Stage Merkel Cell Carcinoma. JAMA Dermatol. 2023. PMID: 37610773.
SUMMARY: This study looked at all T1/T2 MCC that had pathologically confirmed negative regional nodes. Study was weighted heavily with cases of WLE (1452) compared to MMS (104). Unadjusted survival for MMS was 87.4%, 84.5%, and 81.8% at 3, 5, and 10 years, respectively. Unadjusted survival for WLE was 86.1%, 76.9%, and 60.9% at 3, 5, and 10 years, respectively. There were more T2 tumors in the WLE group (20.8% vs 11.5% in the MMS group), although the multivariable hazard ratio for MMS was 0.59 (p=0.4). Patients receiving WLE did seem to be slightly unhealthier overall (Charlson-Deyo comorbidity index score >0 in 27.2% vs 18.3% in MMS group), although patients in MMS group did have slightly more baseline risk factors. MMS patients were more likely to be treated in an academic center, but rates of treatment with adjuvant radiotherapy were similar.