A malignant tumour in disguise
However, the histology showed a moderately differentiated squamous cell carcinoma with perineural spread. Spread along a larger nerve can take a tumour well outside its obvious clinical margins.
Keratoacanthomas can spontaneously regress and disappear from the skin surface. However, if this lesion had been left to see if it regressed, the result would have been disappointment! It is difficult to be certain of histology from how a lesion looks clinically.
All suspected keratoacanthomas should be surgically removed when first diagnosed, even the day the patient presents. A delay of