Infiltrating aggressive epitheliosis of the temporal bone: a newly described disease entity.

Two patients with a highly destructive histologic nondysplastic squamous epithelial lesion of the temporal bone are described. Both tumors were characterized by the production of copious amounts of keratin material which progressively extended in the temporal bone, surrounding bony structures, soft tissue and intracranially, with concomitant functional disorders. Only small amounts of epithelial cells were found. CT scanning revealed extensive and progressive destruction of the temporal bone, skull base in both patients, clivus and arch of atlas in one patient, besides intracranial and intracerebellar abscess formation. Despite extensive surgical therapy, the disorder was unmanageable. Histology showed a normal squamous epithelial basal cell layer with remarkable acanthosis and extensive hyperkeratosis. Material obtained at autopsy demonstrated intracerebellar extension of keratin material in one patient and in the hemicerebellectomy specimen of the other patient. To our knowledge, this disease entity has not been reported before.