My husband also developed skin metastsis in the last stage of his illness. This was the first indication we had that his cancer had recurred, a CT scan then confirmed it was also in his lungs. His doctor indicated that when it metatasised to the skin the disease was very aggressive and not likely to respond to further treatment. Death followed in 3 weeks time. Palliative symptom treatment was instituted and I was able to care for him at home until his peaceful death.
It is still squamous cell carcinoma as metastsis related to the primary source of oral cancer.