Pachydermoperiostosis or primary hypertropic osteoarthropathy is a rare hereditary disorder that was first described in 1868. It is characterized by digital clubbing, pachydermia (thickening of the facial skin and/or scalp), and periostosis (swelling of periarticular tissue and subperiosteal new bone formation). We report a case of a patient with the complete form of the disease, and with a unique appearance of the hair shaft and eyelashes. The authors propose a possible mechanism to justify the abnormalities observed in the patient's hair shafts regarding the metabolism of prostaglandins and its relationship with the hair follicle physiological cycle.