Mastoid Osteoma of Temporal Bone – A Rare Case Report

Abstract

A 40-year-old female presented to Outpatient Department of our hospital with the chief complaint of hard swelling in post auricular region for 3-4 years which was progressively increasing in size. She didn't complain of any pain or other symptoms related to swelling except for cosmetic deformity. On examination, there was a single pyramidal shaped swelling with smooth margin of size around 5.5 x 4.5 cm at left post auricular region [Table/ Fig-1]. Swelling was bony hard in consistency, covered with skin, non tender and its base fixed to underlying bone. Surrounding area was devoid of any sinus or fistula. Past history of patient didn't reveal any history of trauma or infection. Otoscopic examination and audiometry were normal.

Mastoid osteoma: A rare incidental finding in an orthodontic patient

“…Spongy osteomas exhibit a central low dense area (comparable to bone marrow) surrounded by sclerotic bone, a pedunculated base, and somewhat faster growth than compact osteomas. 17,21 In our case, the clinical findings of an asymptomatic, slowly growing lesion and radiographic features of a well-delimited cortical bone-like outgrowth with typical osseous architecture determined the diagnosis of mastoid osteoma.…”

“…14 Mastoid osteomas are temporal osteomas attached to the cortex of the mastoid bone and are very rare, representing about 0.1% to 1% of all benign tumors of the skull. 1 3 5 6 15 16 17 Mastoid osteomas have a higher incidence in females, predominantly in the second and third decades of life. 3 18 Our patient supports these tendencies.…”

“…Histologically, mastoid osteomas have 2 variants depending on the proportions of dense and cancellous bone. 1 6 17 21 25 Compact or ivory osteomas are more common and have a normal-appearing lamellar bone with minimal marrow tissue and an occasional Haversian system. Spongy or cancellous osteomas are rare and contain trabeculae of mature lamellar bone with fatty fibrous marrow and osteoblasts.…”

“…CT is the imaging method of choice to evaluate mastoid osteomas and is useful to differentiate it from other mastoid osseous tumors of the temporal bone. 3 10 17 21 Radiographically, mastoid osteomas appear as a well-circumscribed osseous outgrowth attached to the outer cortex of the mastoid bone and may be pedunculated or sessile. Compact osteomas appear as a homogenous sclerotic overgrowth with a density similar to healthy cortical bone, have a sessile base, and show prolonged slow growth.…”

“…Spongy osteomas exhibit a central low dense area (comparable to bone marrow) surrounded by sclerotic bone, a pedunculated base, and somewhat faster growth than compact osteomas. 17 21 …”