Rare Diagnosis of a Proliferating Pilar Tumor in a Facial Hairline Cyst

A 59-year-old woman who had a lump excised from her frontal scalp region was initially diagnosed with a sebaceous cyst, a common benign tumor filled with keratin typically found on the scalp, face, neck, and trunk. However, histopathological examination revealed that the lump was actually a rare Proliferating Pilar Tumor (PPT), which is derived from the hair follicle's external root sheath. The tumor displayed signs of malignancy, including keratinization, enlarged cells with nuclear pleomorphism, prominent nucleoli, and abundant pale eosinophilic to clear cytoplasm. There were also mitotic figures with abnormal forms and areas of calcification. The final diagnosis was a PPT with focal malignancies, leading to the patient being referred to a specialist team for further management.