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Year : 2017  |  Volume : 6  |  Issue : 3  |  Page : 176-178

Mastoid osteoma: Report of a case and literature review

Regional Centre for Neurosurgery, Usmanu Danfodio University Teaching Hospital, Sokoto, Nigeria

Date of Web Publication6-Feb-2018

Correspondence Address:
Dr. Nasiru Jinjiri Ismail
Department of Neurosurgery, Regional Centre for Neurosurgery, Usmanu Danfodio University Teaching Hospital, Sokoto
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sjhs.sjhs_48_17

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Mastoid osteoma is a benign osteogenic tumor with few reported cases in the literature. The exact cause is unknown; however, developmental anomaly, trauma, and infection have been implicated. Majority are asymptomatic, and diagnosis can be made with computed tomography scan. Surgical excision is curative and offers acceptable cosmetic results. We aimed to report a case of mastoid osteoma coexisting with subgaleal lipoma and outline its management. A 35-year-old woman presented with left mastoid and frontal swellings because of unacceptable disfigurement. Clinical and radiological evaluation was suggestive of mastoid osteoma and sublingual lipoma. The diagnosis was confirmed by histology, after total surgical excision. The patient made uneventful recovery and had acceptable curative and esthetic results. Mastoid osteoma can occur alone or in association with other lesions such as lipoma, especially in syndromic type. In general, asymptomatic and cranial computed tomography scan remained an imaging of choice and surgical resection confers good outcome.

Keywords: Mastoid osteoma, subgaleal lipoma, surgical excision

How to cite this article:
Ismail NJ, Lasseini A, Koko AM, Shehu BB. Mastoid osteoma: Report of a case and literature review. Saudi J Health Sci 2017;6:176-8

How to cite this URL:
Ismail NJ, Lasseini A, Koko AM, Shehu BB. Mastoid osteoma: Report of a case and literature review. Saudi J Health Sci [serial online] 2017 [cited 2022 Jul 4];6:176-8. Available from: https://www.saudijhealthsci.org/text.asp?2017/6/3/176/224749

  Introduction Top

Osteoma is a benign osteoblastic neoplasm, characterized by the proliferation of mature osseous tissue with a laminar pattern.[1],[2],[3]

The incidence of mastoid osteoma is 0.1%–1% of all benign head and neck tumors, and only about 150 cases have been reported in the literature.[4],[5] The exact cause of mastoid osteoma is unknown; however, developmental anomaly, trauma, and infections are implicated.[1],[6],[7]

Most patients with mastoid osteoma are asymptomatic and sought for care due to cosmetic reasons or when there is external auditory meatus obstruction. Computed tomography scan is the standard imaging for diagnosis and surgical excision remained the treatment of choice.[4]

  Case Report Top

A 35-year-old woman presented with the complaints of left retroauricular swelling for 15 years and left frontal swelling for 5 years [Figure 1] and [Figure 2]. Both swellings were painless with gradual increase in size. No history of trauma, symptoms of inflammation, or occlusion of the left ear canal. Treatment was sought due to unsightly appearance of the swellings.
Figure 1: Preoperative photograph of the patient

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Figure 2: Preoperative photograph showing both mastoid osteoma and lipoma

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Clinical examination revealed a left mastoid bony mass, about 6 cm × 5 cm and left frontal firm, lobulated mass, about 3 cm × 4 cm [Figure 1] and [Figure 2]. An otoscopic examination was normal.

Cranial computed tomography scan demonstrated a hyperdense lesion arising from the mastoid cortex, suggesting a typical osteoma [Figure 3]. Complete surgical excision of both masses was done through a curvilinear retroauricular incisions and a linear paramedian incision, respectively [Figure 4] and [Figure 5].
Figure 3: Cranial computerized tomography scan and intraoperative picture of osteoma being chiseled out

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Figure 4: Intraoperative picture of osteoma being chiseled out

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Figure 5: Intraoperative photograph showing osteoma and lipoma after total excision

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Histology confirms the diagnosis of osteoma and lipoma. Postoperative course was uneventful and no recurrence was observed at last follow-up visit 6 months after the surgery [Figure 6].
Figure 6: Postoperative photograph 6 months after surgery

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  Discussion Top

An osteoma is a benign slow-growing osteogenic tumor; it commonly affects frontal and ethmoidal sinuses. Temporal osteomas are extremely rare and <200 cases have been reported in the literature; within the temporal bone, osteoma rarely affects the mastoid but commonly involves external auditory meatus, middle ear, and styloid process.[8] Mastoid osteoma has an incidence of 0.1%–1% of all benign tumors affecting head and neck region.[4],[6],[8]

As in our case report of a 35-year-old female, mastoid osteoma is more common in females.[6],[9] However, male preponderance has been reported in the literature.[9] The exact cause of osteoma is unknown; theories that try to state the cause have been proposed. Developmental theory elucidated by Conheim stated that, osteoma occur at the junction of two bones from different embryonic origin.[7],[8] In our index case, the tumor occurs near the suture between temporal and occipital bone.

Infectious induced osteoma theory stated by Dowling J. R that sinusitis serves as stimulus to proliferation of osteoblasts in the mucoperiosteal lining of sinuses.[7] Other etiological factors implicated include trauma and irradiation and none was identified in this report.[5] Most cases of mastoid osteoma are asymptomatic; patients usually present for cosmetic reasons or symptoms of external auditory meatal obstruction.[4] This is in tandem with our index case that had no complaint other than unacceptable disfigurement.

Osteomas have been classified based on composition into spongious (osteoma spongiosum), compact osteoma, and mixed type (osteoma mixta); based on direction of growth into exosteoma and endosteoma; based on surface characteristics into smooth and multilobular; by number into single and multiple; and based on symmetry into symmetrical and asymmetrical.[7],[10] In our case report, the osteoma was unilateral, outward growing, smooth surfaced, and solitary.

Osteoma can be nonsyndromic or syndromic. Gardner's syndrome is an autosomal dominant disease characterized by colorectal polyposis with malignant potential and extraintestinal lesions (multiple skeletal osteomas, lipomas, subcutaneous fibromas, epidermoid cysts, desmoids tumors, etc.).[10]

The case we presented has both mastoid osteoma and subgaleal lipoma with no features of colorectal polyposis.

Cranial computed tomography scan is the imaging of choice for diagnosis of mastoid osteoma.[10] Our patient did cranial computed tomography scan that demonstrates a hyperdense lesion affecting outer cortex of the left mastoid bone. The differential diagnosis of mastoid osteoma include osteosarcoma, metastases, multiple myeloma, giant cell tumor, Paget's disease and fibrodysplasia.[10]

The osteoma is composed of the mature bone, a dense lamina organized with canals of havers.[1] The treatment of mastoid osteoma is surgical excision. The indications are esthetic disfigurement and rarely features of external auditory meatal obstruction, pain, and neurological symptoms attributable to involvement of adjacent structures.[1] Our case had total excision with excellent curative and cosmetic results. Prognosis of osteoma has been good; recurrence is rare and malignant transformation has not been reported in literature.[1]

  Conclusion Top

Mastoid osteoma coexisting with subgaleal lipoma is extremely rare. Most are asymptomatic but unsightly appearance remains common reason for surgical care. Cranial computed tomography scan confirms diagnosis, rules out differentials, and aids surgical planning.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understand that name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.


We are grateful to entire staff of department of neurosurgery and perioperative nurses for their cooperation.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Pereira CU, de Carvaho RW, de Almeida AM, Dantas RN. Mastoid osteoma: Consideration on two cases and literature review. Int Arch Otorhinolaryngol 2009;13:350-3.  Back to cited text no. 1
Alotaibi N, Hanss J, Benoudiba F, Bobin S, Racy E. Endoscopic removal of large orbito-ethmoidal osteoma in pediatric patient: Case report. Int J Surg Case Rep 2013;4:1067-70.  Back to cited text no. 2
Verma SK, Kalsotra G, Vaiphei K, Panda NK. Large central osteoma of maxillary sinus: A case report. Egypt J Ear, Nose, Throat Allied Sci 2012;13:65-9.  Back to cited text no. 3
Al-Yahya SN, Hamizan AK, Zainuddin N, Arshad AI, Ismail F. Mastoid osteoma: Report of a rare case. Egypt J Ear, Nose, Throat Allied Sci 2015;16:189-91.  Back to cited text no. 4
El Fakiri M, El Bakkouri W, Halimi C, Aït Mansour A, Ayache D. Mastoid osteoma: Report of two cases. Eur Ann Otorhinolaryngol Head Neck Dis 2011;128:266-8.  Back to cited text no. 5
Ahmadi MS, Ahmadi M, Dehghan A. Osteoid osteoma presenting as a painful solitary skull lesion: A case report. Iran J Otorhinolaryngol 2014;26:115-8.  Back to cited text no. 6
Akamatsu T, Tanaka R, Fukui T, Miyasaka M, Yamada S. A case of mushroom shape temporal bone osteoma. Tokai J Exp Clin Med 2009;34:87-91.  Back to cited text no. 7
Abdel Tawab HM, Kumar V R, Tabook SM. Osteoma presenting as a painless solitary mastoid swelling. Case Rep Otolaryngol 2015;2015:590783.  Back to cited text no. 8
Güngör A, Cincik H, Poyrazoglu E, Saglam O, Candan H. Mastoid osteomas: Report of two cases. Otol Neurotol 2004;25:95-7.  Back to cited text no. 9
Mustafa A. Osteoma of mastoid process obstructing external auditory canal: A case report. Health 2012;4:222-4.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

This article has been cited by
1 Osteoma: A Rare Case of Painless Postauricular Swelling
Rachna Dhingra,Jai Lal Davessar,Nupur Midha,Harinder Singh,Shamim Monga
Indian Journal of Otolaryngology and Head & Neck Surgery. 2018;
[Pubmed] | [DOI]


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