Tumor

Key Radiographic Findings
1-Cortical destruction, 2-Periostitis, 3-Zone of transition

• Benign:
  1-No cortical destruction
  2-Benign periostitis: thick wavy, uniform or dense = low-grade chronic irritation
  3-Narrow zone of transition; can be traced with a pencil
• Malignant:
  1-Cortical destruction
  2-Aggressive periostitis: lamellated (onion-skinned), amorphous, sunburst
  3- Wide zone of transition; imperceptible
• Permeative lesions (multiple small holes): not easily categorized as benign vs malignant: multiple myeloma, primary lymphoma of bone, Ewing's sarcoma

Benign Skeletal neoplasm fracture risks
-plain radiograph criteria: increased risk of fracture if the defect length is >3.3 cm, the defect width is >2.5 cm or there is more than 50% of the cortex involved as measured on A/P or lateral x-rays.
-CT-based rigidity analysis is more specific (97% specific vs 12% for xray). (Leong NL, JBJS 2010;92:1827)

Metastatic Bone Disease

• "viscious cycle" of lytic bone metastases from TGFb-mediated release of PTHrP  stimulating osteoclastic resorption of bone and releasing more TGFb.  Consider antiresorptive therapy with zoledronic acid or denosumab.
• Bickels J, JBJS 2009;91A:1503
• Biermann S, JBJS 2009;91A:1518

Syndromes

• Mazabraud Syndrome: fibrous dysplasia and intramuscular myxomas. Rarely can develop osteosarcoma. (Crawford EA, JBJS 2009;91A:955
• Klippel-Trenaunay Syndrome: rare congenital disorder characterized by the triad of cutaneous capillary malformation, varicose veins, and hypertrophy of bone and soft tissue (Kihiczak GG, Int J Dermatol 2006;45:883).
• Morquio Disease (MPS IV): autosommal-recessive defect in the activity of one of two enzymes, N-acetylgalactosamine-6-sulfate (MPS-IVA_ or beta-galactosidase (MPS IVB); results in the accumulation of keratan sulfate and chondroitin-6 sulfate (Montano AM, J Inherit Metab Dis 2007;30:165).
• Fibrodysplasia Ossificans Progressiva: rare; disabling autosomal dominant disorder of joint malformation and progressive heterotopic ossification caused by a recurrent missense point mutation in activin receptor IA (ACVRI / ALK2 / a BMP type I receptor). (Moore R, JBJS 2009;91A:1497).
• McCune-Albright syndrome:  polyostotic fibrous dyplasia and endocrine disturbances, especially precocious puberty.   Hyperpigmentantion with jagged border("Coast of Maine" border).

Lipoma

• MRI:homogenous with density of subcutaneous fat on all sequences.No enhancement
• Treatment  =marginal excision.

Aneurysmal bone cysts

• frequently occur in the first two to three decades of life
• pain and a slow-growing lesion.
• Xray= expansile lesion with septae or striations.
• Treatment = curettage and grafting of the lesion.

Osteomyelitis

• xray = typically shows lucency of bone, periosteal reaction, and a permeative pattern

Giant cell tumor of the tendon sheath

• often arises from the synovial lining of tendon sheaths
• frequently found in the hand and foot.  Slow growing but can invade adjacent structures. 
• Treatment = excision

Giant cell tumor

• epiphysis of long bone
• xray = radiolucent lesion with a small rim of reactive bone.