A misdiagnosed keratoacanthoma turned out to be a metastatic parotid carcinoma

Distinguishing keratoacanthoma from well-differentiated squamous-cell carcinoma is often difficult on account of the clinical and histopathological similarities between them. Since the outcome of treatment depends on identifying the correct diagnosis and having the correct treatment on time, it is essential to differentiate keratoacanthoma and squamous-cell carcinoma as soon and accurately as possible. A paradigmatic case is herein reported. An 85 year-old female underwent total parotidectomy and ipsilateral neck dissection due to the squamous-cell carcinoma of the parotid gland. The investigations, in order to determine whether the tumour was a metastatic or a primary one, led to a misdiagnosis. A prior skin lesion, which was excised over her left cheek one year ago in another clinic, was diagnosed as keratoacanthoma. However, the histopathological revision of the specimen revealed that the lesion was in fact a squamous-cell carcinoma. Thus the parotid tumour was accepted as metastatic squamous-cell carcinoma rather than primary squamous-cell carcinoma.