Pott's puffy tumor:

Answer. A. Subperiosteal abscess of frontal bonePott's puffy tumor, first described by Sir Percivall Pott in 1760, is a rare clinical entity characterized by subperiosteal abscess associated with osteomyelitis. It is characterized by an osteomyelitis of the frontal bone, either direct or through haematogenous spread. This results in a swelling on the forehead, hence the name. The infection can also spread inwards, leading to an intracranial abscess. Pott's puffy tumor can be associated with coical vein thrombosis, epidural abscess, subdural empyema, and brain abscess.