Pott's puffy tumor: a complication of frontal sinusitis. In children sinusitis is a frequent complication of upper respiratory infections but an infrequently considered diagnosis. Although most sinus infections are resolved without complications, when complications do occur they can be serious or life threatening. The most common ones occur in the orbit, but CNS extension is not infrequent. Osteomyelitis and resulting subperiosteal abscess of the frontal bone--the so-called Pott's puffy tumor--is a less common, and perhaps less frequently recognized, serious complication of frontal sinusitis. This paper describes two patients with subperiosteal abscess resulting from frontal sinusitis, one with CNS and orbital extension. A brief literature review is presented, and presentation, diagnosis, and treatment are discussed. 