Benign Bone Forming lesions 1. Osteoid Osteoma 2. Osteoblastoma 3. Osteoma ( Bone Island )
Osteoid Osteoma -Pathogenesis Unknown origin Maybe Vascular or inflammatory in origin No malignant changes have ever been reported
Osteoid Osteoma Age : young males Found in the first three decades of life, but can occur in elderly M:F = 3 :1 > 50 % cases involving the proximal femur or tibia
Osteoid Osteoma Posterior spine and humerus In the diaphysis or the metaphysis of the bone The tumor may be found in cortical or cancellous bone
Osteoid Osteoma -Clinical Insidious onset of localized dull pain Worse at night Relieved by NSAID Joint pain may be present with a periarticular lesion Synovitis can occur secondary to a lesion in the subarticular bone When in a vertebra, scoliosis may occur
Osteoid Osteoma -Clinical Localized swelling Bowing, leg length discrepancy Local signs can also include: an increase in skin temperature increased sweating tenderness
Osteoid Osteoma - Radiography Radiolucent nidus surrounded by a reactive sclerosis in the cortex of the bone The center can range from partially mineralized to osteolytic to entirely calcified The lesion can occur in: cortex cortex and medulla only the medulla
Osteoid Osteoma - Radiography Round/oval lucency 1-1.5 cm Surrounding zone of dense reactive bone Cortex may appear expanded
Osteoid Osteoma - Radiography
Osteoid Osteoma - Differential Diagnosis Osteoblastoma (The nidus is > 1 cm ) Osteomyelitis (Brodie’s Abscess) Stress Fracture
Osteoid Osteoma - CT Scan CT is the preferred if lesion is in the spine or obscured by reactive sclerosis Bone window best setting
Osteoid Osteoma - CT Scan
Osteoid Osteoma - CT Scan
Osteoid Osteoma - MRI Not needed if x-ray and CT diagnostic Helpful for medullary lesions Early lesions show surrounding edema Nidus has low intensity signal Surrounding edema resolves in older lesions
Osteoid Osteoma - MRI
Osteoid Osteoma - MRI
Osteoid Osteoma - Bone Scan Increase uptake in the nidus of the lesion Lesser degree of uptake in the reactive bone Detect small lesions that may be overlooked
Osteoid Osteoma - Bone Scan
Osteoid Osteoma - Histology A brownish-red, mottled and gritty lesion Immature woven trabeculae Variable degree of mineralization Vascular channels lining the trabeculae
Osteoid Osteoma - Histology
Osteoid Osteoma - Treatment Conservative : NSAID En bloc excision Surgical curettage of easily localized lesions has recurrence rate of 5% Intra lesional curettage of obscure lesions has up to 30% recurrence rate Intra-operative localization with technetium or CT placed guide wire Radiofrequency ablation
Osteoid Osteoma - Treatment
Osteoid Osteoma - Treatment
Osteoblastoma Age : 15 – 30 , mean of 20 years M:F=2:1 A solitary, benign and self-limited tumor that produces irregular bars of poorly mineralized osteoid The tumor occurs in the posterior vertebral column ( 50% ) , the metaphysis or diaphysis of long bones
Osteoblastoma - Etiology Unknown Benign aggressive lesion of bone (along with GCT, Chondroblastoma, ABC)
Osteoblastoma - Clinical Pain of long duration, swelling and tenderness Non traumatic backache Tumors of the spine can cause scoliosis and neurological symptoms Laboratory data normal
Osteoblastoma - Radiography A radio-lucent defect with a central density due to ossification Well circumscribed and may have a surrounding sclerosis (geographic) Cortical thinning, expansion of the bone, soft tissue swelling at late stage Spine: well-defined expansile lesion
Osteoblastoma - Radiography May be predominantly radiolucent in early lesions Variable degrees of mineralization as lesion ages Thin rim of reactive bone * Characteristics of a benign aggressive lesion
Osteoblastoma - Bone Scan Intense uptake that corresponds to the radiographic lesion Early increase on vascular phase Most useful for radiographically obscure spinal lesions
Osteoblastoma - MRI Non specific findings Low to intermediate signal on T1 imaging Increased signal on T2 imaging Less reactive edema than Osteoid Osteoma Soft tissue extension
Osteoblastoma - Histology Red to tan in color with hemorrhagic areas Thick, woven trabeculae lined with osteoblasts Highly vascularized connective tissue Identical to osteoid osteoma
Osteoblastoma - Treatment En bloc excision when practical Curettage and bone graft for spine lesions Recurrence about 20% Larger resections may require bone grafting and internal fixation No data on adjuvant treatment
Osteoma ( Bone Island) A benign bone growth Age : 25 - 50 , M = F Large osteomas : clavicle, pelvis, and tubular bones Surface lesions have predilection for flat bones and tibial diaphysis Intramedullary lesions predilection for metaphysis of long bones
Osteoma - Pathogenesis Cortical bone that has failed to undergo medullary resorption during the process of endochondral ossification May arise on the surface ( Osteoma ) Maybe intramedullary ( Bone Island , enostosis )
Osteoma
Osteoma - Clinical Surface lesions: slowly growing lesions Multiple osteomas are associated with Gardner's syndrome (intestinal polyposis, scalp lipomas) Bone islands are almost invariably asymptomatic lesions
Osteoma - Radiography Central osteomas are well delineated sclerotic lesions with smooth borders Peripheral osteomas are radiopaque lesions with expansive borders that may be sessile or pedunculated
Osteoma - Histology Dense, mature cortical bone No Haversian canals No fibrous component No peripheral reaction to the lesion
Osteoma - Treatment Treatment of osteomas is only necessary if they are symptomatic Marginal excision of symptomatic surface osteomas Enostoses require no treatment