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Merkel cell carcinoma

Key sources
The following summarized guidelines for the evaluation and management of merkel cell carcinoma are prepared by our editorial team based on guidelines from the German Society of Dermatology (DDG 2023), the U.S. Preventive Services Task Force (USPSTF 2023; 2018), and the European Association of Dermato-Oncology (EADO/EDF/EORTC 2022).


1.Screening and diagnosis

Indications for screening: as per USPSTF 2023 guidelines, insufficient evidence to assess the balance of benefits and harms of visual skin examination by a clinician to screen for skin cancer in adolescents and adults.
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2.Classification and risk stratification

Staging: use the current AJCC TNM classification for postoperative staging.

3.Diagnostic investigations

Clinical assessment
As per DDG 2023 guidelines:
Inspect the entire skin and palpate the surrounding skin and regional lymph nodes in addition to inspection of the tumor.
Use appropriate questionnaires, such as the QoL in Late-Stage Dementia questionnaire or the Cognitively Impaired Life Quality scale, in patients with cognitive impairment or dementia.

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  • Imaging for staging

4.Diagnostic procedures

Biopsy and histopathology
Perform complete excision of cutaneous neoplasms of uncertain biological behavior and obtain a histological examination. Perform biopsy with histological analysis if complete excision is not feasible.
Obtain stepwise immunohistochemical studies to confirm the histological diagnosis of MCC and exclude differential diagnoses.

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  • Sentinel lymph node biopsy

5.Medical management

Systemic therapy
As per DDG 2023 guidelines:
Assess for indications for systemic therapy, including PD-L1 inhibitors as first-line therapy,
in patients with locally advanced disease or distant metastases unsuitable for surgery or radiotherapy.
Assess for indications for chemotherapy in case of disease progression on immunotherapy or contraindications for immunotherapy.

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  • Palliative care

6.Therapeutic procedures

Adjuvant radiotherapy
As per DDG 2023 guidelines:
Offer adjuvant radiotherapy of the tumor bed even after complete resection. Administer a total dose of 50 Gy (single dose 2 Gy). Irradiate the tumor bed with a safety margin of 3 cm allowing for an adequate dose to be delivered to the skin (bolus).
Offer irradiation of the affected lymph node basin in patients with positive sentinel node biopsy (micrometastasis). Consider offering irradiation of the affected lymph node basin in patients with negative sentinel node biopsy with increased risk of false negative results or recurrence (maximum tumor diameter > 2 cm). Administer a total dose of 50-56 Gy in subclinical tumors and ≥ 56 Gy in macroscopic/clinically manifest tumors.

7.Surgical interventions

Surgical resection: as per DDG 2023 guidelines, perform complete excision with adequate surgical margins in patients with primary tumors without evidence of organ metastases.

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  • Lymph node dissection

  • Resection of distant metastases

8.Follow-up and surveillance

As per DDG 2023 guidelines:
Obtain close follow-up at 3-month intervals in patients with MCC, given the increased risk of locoregional recurrence within the first 2 years after the initial diagnosis. Consider continuing follow-up at 6-month intervals for another 3 years after 2 years.
Consider obtaining additional close follow-up with cross-sectional imaging (18-FDG-PET/CT or a combination of ultrasound, CT, and MRI) in the first 2 years in patients with ≥ stage III disease or in case of lacking sentinel lymph node status.

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  • Management of recurrent disease