Mastoid Osteomas: Report of Two Cases Atila Gungor, Hakan Cincik, Ethem Poyrazoglu, Omer Saglam, and Hasan Candan Gulhane Military Medical Academy, Haydarpasa Training Hospital, Department of ENT, Istanbul, Turkey Objective: To discuss the differential diagnosis of two cases with mastoid mass. Study Design: Case report and review of the literature. Setting: The study was carried out in Gulhane Military Medi- cal Academy, Haydarpasa Training Hospital, Istanbul, Turkey. Patient, Intervention, and Results: Both cases were 23-year- old males. They admitted to our clinic with masses behind their left ears that had been progressively enlarging for 5 years. In both cases, coronal and axial computerized tomography scans revealed a wide-based lesion involving temporal bone cortex. The cases were operated on for diagnosis and for correction of the cosmetic deformity. Histopathological examinations were consistent with mixed and spongiotic osteoma. Conclusions: Mastoid osteoma is a rare, benign tumor of bone. It may cause cosmetic deformity such as external mass or an auricular protrusion. Other neoplasms of the mastoid region, such as osteosarcoma and osteoblastic metastasis, should be considered for the differential diagnosis. Key Words: Os- teoma—Mastoid bone—Osteosarcoma. Otol Neurotol 25:95–97, 2004. Osteomas in the head and neck regions are benign bone neoplasms usually found in the frontoethmoid area. Temporal bone osteoma is a rare entity (1). When located in the mastoid and squamous parts of temporal bone, osteomas can cause cosmetic deformity such as external mass or an auricular protrusion (2). Other neoplasms of the mastoid region such as osteosarcoma and osteoblastic metastasis should be considered for the differential diag- nosis (3). The two cases presented in this article are mastoid osteomas operated on for diagnosis and for correction of the cosmetic deformities. CASE REPORTS The patients in both cases were 23-year-old men. They admitted to our clinic with progressively enlarging masses behind their left ears for a duration of 5 years. There was no additional history such as tinnitus, hearing loss, vertigo, auricular discharge, trauma, or facial pa- ralysis. Physical examination of each patient revealed a painless bone mass with approximately 3 × 2.5 cm in size in the left postauricular area. Both masses had smooth surfaces and the skin was not involved. The skin tem- perature and skin color were normal. Otoscopic exami- nation and audiologic tests were also normal. In both cases, coronal and axial computed tomography (CT) scans revealed a wide-based lesion involving the temporal bone cortex. The middle and inner ear were normal, and the facial nerve was not involved in either case (Figs. 1 and 2). The cases were operated on for the purpose of diag- nosis. A classic postauricular incision and periosteal elevation were performed, and the masses were exposed. The masses were removed entirely to the normal cortical level by a chisel. The bases were drilled until normal mastoid air cells were identified. There were no com- plications in the postoperative period. We sent the speci- mens for histopathologic examination, which were consistent with mixed and spongiotic osteoma. We ob- served varying degrees of osteoblastic and osteoclastic activity but no hematopoietic cells. Follow-up CT scans taken a year after the surgeries showed no evidence of recurrence. DISCUSSION Osteomas have been reported in all portions of the temporal bone, including the squama, mastoid, internal and external auditory canal, glenoid fossa, middle ear, eustachian tube, petrous apex, and styloid process (1– 3,8). Denia et al. (2) reported that extracanalicular os- teomas of temporal bone are most commonly located in the mastoid portion. Probst et al. (4) reviewed the litera- ture and found only 92 recorded cases of mastoid osteo- mas since 1861. The literature was reviewed again and two cases were reported as mastoid osteoma by D’Ottovai et al. (5) in 1997; they found 100 reported cases in the world literature before theirs. Address correspondence and reprint requests to Dr. Atila Gu ¨ngo ¨r, GATA, Haydarpas ¸a Eg ˘itim Hastanesi, KBB Klinig ˘i, 81327 Kadı `ko ¨y/I stanbul, Turkey; E-mail: atilagungor@superonline.com Otology & Neurotology 25:95–97 © 2004, Otology & Neurotology, Inc. 95