- Design
- Retrospective single-centre case series
- Population
- 13 patients aged 18 to 50 with Merkel cell carcinoma
- Primary outcome
- Clinicopathologic features and overall survival
- Effect
- Nodal metastasis at presentation 60.0%; overall survival 74.1% at 2 years and 59.3% at 5 years
A single-centre retrospective series reviewed 13 patients aged 18 to 50 years with Merkel cell carcinoma diagnosed between 2009 and 2025. The median age was 40 and 61.5% were female.
Of 11 patients with data, 36.4% had pre-existing immune suppression. Tumours were deep, with a median Breslow depth of 10.5 mm and mitotic rate of 46 per mm². Merkel cell polyomavirus was found in 5 of 8 assessable cases (62.5%). At presentation 60.0% had nodal metastasis, and distant metastasis developed in 54.5%. Estimated overall survival was 74.1% at 2 years and 59.3% at 5 years.
With 13 patients the percentages are fragile, and referral bias to a tertiary centre is likely. The practical point for the pathologist is to keep Merkel cell carcinoma in the differential for an aggressive neuroendocrine-looking tumour in a younger or immunosuppressed patient.
- Keep Merkel cell carcinoma in mind for neuroendocrine-looking cutaneous tumours in younger patients.
- Ask about immune suppression on the request form when reviewing such a tumour.
- Immunohistochemistry was consistent with Merkel cell carcinoma in every case.
- Do not generalise percentages from 13 patients.
Why it matters
It reminds pathologists that a rare tumour of older adults can occur earlier, with similar aggressiveness.
Don't overread it
A single-centre series of 13 patients cannot define the disease in the young.
The statistics, in plain English
In 13 people each patient is nearly 8% of the series, and with only 8 assessable for the virus a single case shifts that figure by over 12 percentage points.
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