Rare diseases · Sign or symptom
Merkel cell skin cancer
HP:0030447
What it means
A malignant cutaneous tumor of the elderly that is characterized by an aggressive course with regional nodal involvement, distant metastases and a high rate of recurrence. Most patients present with rapidly growing, painless, firm, non-tender, dome-shaped red, occasionally ulcerated skin nodules, which have a red or bluish color, measuring up to several centimeters, on predominantly sun-exposed areas of the body. The overlying skin is smooth and shiny, sometimes exhibiting ulcerative, acneiform or telangiectatic features.
Rare diseases that can present with this1
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Anaplastic carcinoma of the skin · Cutaneous APUDoma · Merkel cell cancer of the skin · Neuroendocrine carcinoma of the skin · Neuroendocrine tumor of the skin · Neuroendocrine tumour of the skin · Primary small cell carcinoma of the skin · Primary undifferentiated carcinoma of the skin
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.