Abstract
Mastoid osteomas are benign, slow growing tumours arising in temporal bone. These are rare; few cases reported till date. Normally are asymptomatic, may present with cosmetic deformity, pain and hearing loss. These are readily excised. Recurrence is rare.
Keywords: Osteoma, Mastoid bone, Temporal bone
Introduction
Osteoma is a benign tumor of mesenchymal osteoplastic nature composed of well-differentiated osseous tissue with laminar structure [1]. Temporal bone osteomas in general constitute 0.1 to 1 % of all benign tumors of the skull. In the temporal bone, the external auditory canal is the predominant location, rarely present in the mastoid, the squamous portion of the temporal bone, inner ear canal and middle ear.
The following report discusses a case of mastoid osteoma.
Case Report
A 30 year-old female reported with a swelling behind right ear for 6 years. It was painless, gradually and progressively increasing in size, associated with forward pushing of right pinna. No history of trauma, headache, hearing impairment, otorrhea, dizziness, vomiting, facial weakness and neurological deficit. On examination, well defined smooth, bony hard, non-tender, non- pulsatile, non-reducible, non-compressible, swelling measuring 5 × 4 cm was present behind right pinna occluding retro auricular groove and fixed to underlying bone. Skin over swelling was free having normal local temperature (Fig. 1). EAC showed no post-aural bulging. Tympanic membrane of right ear was intact. Left ear was normal. Audiometric evaluation showed normal hearing.
Fig. 1.
a Pre-operative photograph of patient showing right post-auricular swelling. b CT scan showing bony outgrowth arising from right mastoid bone measuring 4.1 × 2.9 cm
FNAC Was Not Possible Due to Hardness of the Swelling
CT scan revealed bony outgrowth arising from right mastoid bone measuring approximately 4.1 × 2.9 cm. Pedunculated bony outgrowth was seen arising from the mastoid cortex near the bony EAC with plane of differentiation between the mastoid cortex and the bony outgrowth. No associated soft tissue swelling (Fig. 1).
Operative Procedure
Patient posted for surgical excision of tumour (Fig. 2) under general anesthesia. Post-auricular incision taken completely exposing osteoma and periosteum elevated. Excision was done by drilling out a groove at base of osteoma over the surface of mastoid cortex under continuous irrigation. Intact, pedunculated osteoma was removed with chisel and hammer. After excision, the contour of mastoid cortex was found intact without any evidence of bony invasion. Excessive skin was removed and suturing was done in layers. There was intra-operative blood loss of 50 ml. Excised mass sent for histopathological examination. The report mentioned the lesion having multiple fragments of bony interconnecting trabeculae separated by fibro-vascular stroma. The trabeculae consisted of concentric layers of lamellae around the neurovascular bundle (Haversian canal) with entrapped osteocytes within the lacunae. Surrounding area showed fibro-vascular stroma and hemorrhage. These features confirmed the diagnosis osteoma of compact type (Fig. 2).
Fig. 2.
a Intraoperative photograph showing dissected osteoma arising from right mastoid bone. b Histopathological slide demonstrating compact type of osteoma
Suture removed on post-operative day 8. Wound was healthy. Patient’s follow up was done for 6 months. No evidence of recurrence.
Discussion
Osteomas are benign tumour of head and neck common in frontal and ethmoidal sinus with exceptionally rare occurrence over mastoid [2]. Osteomas are reported in all portions of temporal bone, including squamous, mastoid, internal and external auditory meatus, glenoid cavity, middle ear, Eustachian tube, petrous apex, and styloid process. D’Ottavi et al. [3] reviewed 100 cases of mastoid osteoma and reported two cases of their own. According to Dominguez Pérez et al. [4] about 150 cases have been reported in the literature in 2010.
It has higher incidence in female patients, predominantly in the 2nd and 3rd decades of life and it is rare in puberty [5]. The etiology of osteoma is unknown, but some suggest a congenital origin. Osteoma may be syndromic associated with Gardner’s syndrome (multiple intestinal polyps, epidermoid inclusion cysts, fibromas of the skin and mesentery and osteomas) or non-syndromic with predisposing factors like trauma, surgery, irradiation, metaplasia, chronic infection, pituitary dysfunction [6]. Osteoma has varied histological types including compact, cartilaginous, spongy or mixed. They usually present as asymptomatic, solitary, gradually progressive swelling rarely greater than 3 cm. Similar presentation is recorded in present case and also various studies like Hazem et al. [7] and El Fakiri et al. [2]. Rarely osteomas lead to facial palsy, SNHL, CHL, sigmoid sinus damage, recurrent ear infections and on invading neighboring structures or widening of periosteum may cause pain. A mastoid osteoma compressing the posterior fossa structures and causing intracranial complications has been reported by Van Dellen [8]. Differential diagnosis of mastoid osteoma includes osteoblastic metastasis, osteosarcoma, giant cell tumour, osteoid osteoma (are painful, have active chemicals and characteristic histological structures), isolated eosinophilic granuloma (specific radiological images), ossifying fibroma, Paget’s disease, hemangioma, calcified meningioma, monostotic fibrous dysplasia (with precise histological characteristics), calcified meningioma, hemangioma and monostotic fibrous dysplasia. It is important to differentiate osteomas from exostoses. Exostoses lack fibro vascular stroma; are usually multiple, broad-based medial to suture line while osteoma are single, pedunculated and lateral to suture line.
CT scan is investigation of choice. Osteomas are easily identified in the cranium radiographic exam as a radiolucent area with a central zone of calcification that expands outwards original bone preserving dipole. Osteoma presents as a low opacity and well delimited osseous tissue, involved by a sclerotic area of high opacity. In rare cases, they can extend medially into the petrous temporal bone adjacent to the facial nerve, lateral semicircular canal or ossicles, here; imaging defines anatomical relations with these structures before considering surgical resection [1]. Magnetic resonance carried to view inflammation around the lesion.
Treatment is surgical excision, advocated for symptomatic and unaesthetic looking cases. Surgical approach depends upon the site, size, preference and experience of the surgeon. In mastoid osteomas, postauricular incision is applied. If osteoma extends into fallopian canal and bony labyrinth, complete excision is not indicated due to vulnerability of these structures. Osteoma involving middle and inner ear observed until they are symptomatic. Surgical management of internal auditory meatus osteoma is done by either middle cranial fossa or sub-occipital approach [9].
Follow-up needed in cases undergoing partial excision or expectant treatment. Malignant transformation has not been found in literature [10]. Recurrence is very rare.
Conclusion
Mastoid osteomas are benign, slow growing tumours arising from temporal bone. They are rare, asymptomatic, may present with cosmetic deformity, pain and hearing loss. They are easily diagnosed by clinical and radiological examination. Surgical excision is done. Prognosis is considered good in cosmetic and curative aspects when completely excised. Recurrence and malignant transformation are un-common.
Compliance with Ethical Standards
Animal Rights
This article does not contain any studies with animals performed by any of the authors.
Conflicts of interest
The authors Dr. Vinod T. Kandakure, Dr. Vaibhav J. Lahane and Dr. Swati Mishra declare that they have no conflicts of interest.
Informed Consent
Informed consent was obtained from all individual participants included in the study.
References
- 1.Carlos UP, de Carvalho RWF, de Almeida AMG, Rafaela ND. Mastoid osteoma. Consideration on two cases and literature review. Int Arch Otorhinolaryngol. 2009;13:350–353. [Google Scholar]
- 2.El Fakiri M, El Bakkouri W, Halimi C, Aı¨t Mansour A, Ayache D. Mastoid osteoma: report of two cases. Eur Ann Otorhinolaryngol Head Neck Dis. 2011;128:266–268. doi: 10.1016/j.anorl.2011.03.001. [DOI] [PubMed] [Google Scholar]
- 3.D’Ottavi LR, Piccirillo E, de Sanctis S, Cerqua N. Mastoid osteomas: review of literature and presentation of 2 clinical cases. Acta Otorhinolaryngol Ital. 1997;17(2):136–139. [PubMed] [Google Scholar]
- 4.Domı´nguez Pe´rez AD, Rodrı´guez Romero R, Domı´nguez Dura´n E, Riquelme Montan˜ o P, Alca´ ntara Bernal R, Monreal Rodrı´guez C. The mastoid osteoma, an incidental feature? Acta Otorrinolaringol Esp. 2011;62:140–143. doi: 10.1016/j.otorri.2010.03.003. [DOI] [PubMed] [Google Scholar]
- 5.Denia A, Perez F, Canalis RR, Graham MD. Extracanalicular osteomas of the temporal bone. Arch Otolaryngol. 1979;105(12):706–709. doi: 10.1001/archotol.1979.00790240020005. [DOI] [PubMed] [Google Scholar]
- 6.Ülkü ÇH, Yücel A. Osteoma of the mastoid region. Kulak Burun Boğaz Uygulamaları (Turkey) 2013;1(3):135–138. [Google Scholar]
- 7.Abdel Tawab HM, Kumar VR, Tabook SM. Osteoma presenting as a painless solitary mastoid swelling. Case Rep Otolaryngol. 2015;2015:590783. doi: 10.1155/2015/590783. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Van Dellen JR. A mastoid osteoma causing intracranial complications: a case report. S Afr Med J. 1977;51:597–598. [PubMed] [Google Scholar]
- 9.Clerico DM, Jahn AF, Fontanella S. Osteoma of the internal auditory canal. Case report and literature review. Ann Otol Rhinol Laryngol. 1994;103:9–23. doi: 10.1177/000348949410300807. [DOI] [PubMed] [Google Scholar]
- 10.Ahmadi MS, Ahmadi M, Dehghan A. Osteoid osteoma presenting as a painful solitary skull lesion: a case report. Iran J Otorhinolaryngol. 2014;26(75):115–118. [PMC free article] [PubMed] [Google Scholar]