A 17-year-old male patient was admitted because of progressive hearing loss since the age of six. His former blood and radiology investigation had revealed idiopathic hyperphosphatasia. On ENT examination bilateral thickened tympanic membranes with severe mixed-type hearing loss was diagnosed. Computerized tomography (CT) demonstrated expansion of the calvarial bones, including the temporal bones, except for the otic capsule. Middle-ear exploration revealed thickened middle-ear mucosa and a stone hard, immobile bony mass instead of the normal ossicular chain at the posterior superior part of the mesotympanum. No ossicular reconstruction could be attempted and the patient was rehabilitated with a hearing aid.
