Update on Bone Forming Tumors of the Head and Neck

Abstract

The production of bone by neoplastic cells that have an osteoblastic phenotype is the common trait of all bone forming neoplasms. The tumor bone can be lamellar or woven in architecture and may mimic cortical or cancellous elements. In benign tumors, the neoplastic bone usually consists of relatively well-formed trabeculae of woven bone, whereas in malignant bone forming tumors (osteosarcoma), it is usually deposited in a coarse lace-like pattern. Lamellar cortical-type neoplastic bone is generally only present in osteoma (and enostosis), however, it can rarely be a component of well-differentiated osteosarcoma. Osteoma Osteoma is a benign, slow growing bone forming tumor that consists primarily of well-differentiated mature, compact or cancellous bone. They usually arise on the surfaces of the cranial vault (outer table—exostotic and inner table—enostotic), jaw, paranasal sinuses, and orbit [17, 22, 42]. Cranial osteomas are named according to the bone from which they arise, whereas osteomas of the paranasal sinuses are designated in relation to the sinus which they invade [4]. In the paranasal sinuses, osteomas most frequently involve the frontal sinus, followed in descending order by the ethmoid sinus, maxillary antrum, and sphenoid sinus [11, 12, 30, 41]. Although rare in children, osteomas affect all age groups but are most commonly diagnosed in the fourth or fifth decades of life [12, 41]. Osteomas are often asymptomatic and are frequently an incidental finding on imaging studies performed for unrelated conditions. Osteomas when large or situated in a strategic location can cause a variety of signs and symptoms including painless swelling, facial asymmetry and symptoms secondary to nasal or paranasal sinus obstruction such as sinusitis, nasal discharge and mucocele formation [12, 13, 16, 45]. Orbital osteomas and paranasal sinus osteomas that protrude into the orbit can cause a variety of ocular abnormalities such as exophthalmos, proptosis, ptosis, diplopia, lid edema or swelling and amaurosis fugax [16, 46]. In extraordinary cases the tumor may grow intracranially and cause neurological complications [1]. Classically, osteomas manifest as a round well-circumscribed homogeneous radiodensity on radiographs; however, several different patterns of mineralization may be seen (Fig. 1) [11]. Open in a separate window Fig. 1 Axial CT of skull showing round well defined osteoma attached to the outer table