Differential diagnosis of Multilocular Radiolucencies – Part 1 Specific learning objective To know the criteria for defining a multilocular radiolucency. To enumerate different diseases with multilocular appearance To know the differentiating radiographic features among them. DR.S.KARTHIGA KANNAN PROFESSOR ORAL MEDICINE & RADIOLOGY

Criteria for Multilocular Radiolucencies

Periapical Radiolucency Pericoronal Radiolucency

Inter-radicular Radiolucency

Introduction Multilocular radiolucency Pathogenesis Multilocular radiolucency classification Multiple, adjacent, frequently coalescing and overlapping pathologic compartments in bone True multilocular lesions contains two or more pathologic chambers partially separated by septa of bone More common in mandible Multilocular cyst Odontogenic keratocyst Simple /Traumatic bone cyst Aneurysmal bone cyst Ameloblastoma Odontogenic myxoma Central giant cell granuloma Cherubism Giant cell lesion of hyperparathyroidism Vascular malformations – central hemangioma

Different Multilocular Radiolucent Appearances Soap Bubble Appearance – Consisting of circular compartments of varying size and appear to somewhat overlap. Honey comb appearance – - Lesions whose compartments are small and tend to be uniform in size Tennis racket appearance – Lesions composed of angular compartments that result from development of more or less straight septa.

Keratocystic Odontogenic Tumor Or Odontogenic keratocyst Multilocular cyst Keratocystic Odontogenic Tumor Or Odontogenic keratocyst The pathology appear unilocular or multilocular cyst clinically but it enlarge by the growth of lining epithelium showing tumor like character –Mural Growth Commonly seen in mandible premolar and molar region Age predilection – 2nd to 3rd decade Sex predilection – Male > Female Grows anterio-posterior initially and asymptomatic and may be noticed on routine examination Later may cause swelling and facial asymmetry, but never causes paresthesia unless secondarily infected.

Radiographic appearence Location 90% posterior body of mandible behind canine Epicentre above inferior alveolar canal Border – well defined, uniform or scalloped Shape – Unilocular or multilocular, May occur in a pericoronal position mimicking like Dentigerous cyst Size – In initial stage – Anterioposterior dimention is more than bucco-lingual direction Internal structure- Uniformly radiolucent, can have curved trabeculae or septa. Effects on adjacent structure -may displace the root/tooth, inferior alveolar canal or cause root resorption, In maxilla encroches antrum. Number – if multiple OKC are detected in Jaw ,should rule out Nevoid Basal cell carcinoma syndrome(NBCC)

Consistency: Depending on cortical plates thickness it may be bony hard, if thin – Tennis ball consistency, futher thinning results in egg shell crackling and if completely destroyed then soft and fluctuant cystic consistency. Aspiration : straw colored fluid with flecks of keratin or thick yellow cheesy keration. Differential Diagnosis Ameloblastoma Giant cell lesions of Hyperparathyroidism Odontogenic myxoma Management Enucleation Marsupialization with chemical cauterizing solution

Aneurysmal Bone Cyst Definition – it’s a reactive bone lesion. It represents an exaggerated proliferative response of vascular tissue in bone. It was separated as a distinct entity by Jaffe & Lichenstein in 1942. Aneurysmal bone cysts (ABC) are expansile osteolytic lesions with thin wall cystic cavities without epithelial lining. Age – In less than 30 yrs Sex - common in female patient. Seen as a fairly rapid bony swelling. Pain is an occasional complaint & involved area is tender on palpation Intra-operative finding – appear as blood soaked sponge with large pores representing cavernous spaces of lesion

Radiographic Features Location -Mandibular molar and ramus is more involved Periphery – well defined, circular in shape Internal Structure – initial lesions are radiolucent – multilocular with internal septa. Surrounding Structures – extreme expansion of outer cortical plate – displace and resorb teeth. Differential Diagnosis Traumatic bone cyst Central giant cell granuloma – ocuur in anterior reion of mandible Ameloblastoma – occurs in older age Management Surgical curettage – autogeneous bone graft.

Central Giant Cell Granuloma Clinical features Age - 2nd decade. Male to Female ratio = 1: 2 Mandible > Maxilla Anterior region > Posterior region Painless – Rapid growing swelling – with tenderness on mild palpation Overlying mucosa is bluish – brown in color Synonyms – giant cell reparative granuloma, giant cell lesions & Giant cell tumor Introduced by Waren – 1837 Described by Jaffe – 1953 – Giant Cell Reparative Granuloma Definition – reactive lesion to unknown stimulus not a true neoplastic lesion Cane be associated with Hyperparathyroidism

Radiographic Features Location – mandible – anterior to 1st molar or anterior to cuspids lesions cross midline. Periphery – well defined lesions borders Internal Structure – subtle granular pattern of calcification – ill defined wispy septa. Surrounding Bone - Causes expansion of cortical bone in maxilla cortical plate is destroyed more easily – displace and resorb teeth, missing lamina dura, displaces inferior alveolar canal inferiorly. Differential Diagnosis Ameloblastoma Odontogenic Myxoma Aneurysmal Bone Cyst Management Medical Managment Corticosteroid injections – Exact mechanism is not known – inhibit bone resorption Calcitonin – causes increased influx of Ca in bones – antagonist to parathyroid. Synthetic Salmon Calcitonin – nasal spray (osteospray) Interferon – differentiate mesenchymal stem cells into osteoblasts , thereby enhancing bone formation in CGCG. Surgical excision with recurrence rate of 11 – 49%

Ameloblastoma Clinical Features It is a true benign neoplasm of Odontogenic epithelium Locally invasive It is the most common odontogenic tumor Arises from reminents of dental lamina or dental organ Types Solid / multicystic Unicystic Desmoplastic Bone resorption is mediated by Interleukin 1 and Interleukin 6 mainly synthesized in stellate reticulum like cells Clinical Features More common in males Age prdilection – 40 yrs Grows slowly with expansion of jaw producing facial asymmetry It can cause migration, tipping, mobility and root resorption. Painless, No paresthesia Initially bony hard in cosistency later may have egg shell crackiling and cystic consistency In multi cystic variant aspiration may yield fluid.

Radiographic appearance Effect on adjacent structure Root resorption, displacement Displacement of tooth, inferior alveolar canal Cortical bone expansion is seen. Maxilla is rarely involved but dangerous as the cortical plates are thin and mayextend to sinus, nasal walls and orbital floor Differential Diagnosis – Odontogenic keratocyst Central giant cell granuloma Treatment – enbloc surgical resection Location – 80% in mandible Molar ramus area Borders – well defined with cortical border and may show scalloping Shape – Unilocular or multilocular Soap bubble / honey comb Pericoronal also. Internal structure – Uniformly radiolucent Curved septa / trabeculae Desmoplastic type shows irregular sclerotic raioopaque mass.

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