Development of a Giant Cornu Cutaneum in a Patient with a Coincidental Foreknown Intracranial Meningioma.

The diagnostic spectrum for scalp lesions is extensive and comprises either benign or malignant features. Cornu cutaneum (CC) is a well-recognized condition; however, its origin and natural course are not always obvious. We present the case of a 78-year-old male patient who was diagnosed with intracranial meningioma in 2014 and who subsequently refused treatment. He presented a new scalp lesion, resembling a horn, in the vertex region 1.5 years after his last follow-up. The lesion was excised, and the patient was histopathologically diagnosed as having CC caused by squamous cell carcinoma. CC can be easily recognized when it resembles animal horn; however, it can assume different shapes that require a physician to be vigilant. Moreover, a lesion’s benign or malignant nature is not obvious in all cases. Hard, protruding scalp lesions should be examined for CC, and a histopathological evaluation should be performed to make a definitive diagnosis.