Pott's puffy tumor is a relatively rare condition and mainly affects children and young adults. It is often secondary to frontal sinusitis with the potential of serious endocranial complications. We report the case of a young adult of 18 years treated for frontal sinusitis and in whom the evolution was marked by an erosion of the external table of the frontal sinus and the development of a subperiosteal abscess. The patient underwent emergency surgical exploration. The rapid diagnosis and the very early stage of our patient allowed us to perform a minimally invasive supra-eyebrow Lynch approach. Considering the risk of dangerous complications, the diagnosis of Pott's puffy tumor must be evoked in front of any inflammatory frontal swelling.