Overview
Many benign bone tumors are asymptomatic, found incidentally and managed by observation with serial radiographs. Surgery is reserved for symptoms, growth, mechanical problems or imaging features that raise concern for a more aggressive lesion. The key clinical task is separating benign lesions from malignant mimics. (Campbell)
Osteoid Osteoma
Features. Benign neoplasm of young men, mostly in the second and third decades, with a predilection for the femur and tibia. No malignant change has been documented. Pain is worse at night and relieved by aspirin or NSAIDs, explained by high cyclooxygenase and prostaglandin levels in the lesion. Near a joint it can cause swelling, stiffness and contracture; in a vertebra it can cause scoliosis.
Imaging. Small (under 1.5 cm) central radiolucent nidus with surrounding sclerosis. CT is best for identifying the nidus. Bone scan shows marked uptake and MRI shows extensive surrounding edema. Biopsy is rarely needed.
Treatment. NSAIDs can serve as definitive treatment if the patient accepts long-term medication; spontaneous healing usually occurs within 3 to 4 years.
Percutaneous radiofrequency ablation (CT-guided core biopsy, then electrode tip heated to 90 C for 6 minutes) is the usual choice for pelvic and long bone lesions, as an outpatient procedure with immediate return to activity and recurrence under 10%. Use great care in vertebral lesions (cord and root injury) and avoid it in small bones of the hand and foot (skin thermal injury).
Burr-down technique: localize the nidus with fluoroscopy, burr away the sclerotic bone directly over it, remove the nidus with curettes for pathology, and burr the cavity again. Minimal reactive bone is removed, limiting fracture risk, with recurrence under 10%. En bloc resection has a low recurrence rate but is rarely indicated in long bones because of fracture risk.
Microwave ablation, cryoablation and MR-guided focused ultrasound are other options under study.
(Campbell)
Bone Island (Enostosis)
Asymptomatic, incidental, most often in the pelvis and femur. Small round or oval area of homogeneous density in cancellous bone with radiating spicules merging with host bone, no destruction or periosteal reaction, and dark signal on T1 and T2 MRI without edema. Osteopoikilosis is the multiple form. Observe with serial radiographs. If pain or growth occurs, biopsy to exclude sclerosing osteosarcoma, blastic metastasis or sclerotic myeloma; a markedly positive bone scan also suggests a more aggressive lesion. (Campbell)
Chondroma (Enchondroma)
The most common tumor of the small bones of the hand and foot, usually found incidentally or after a pathologic fracture. Radiographs show stippled, punctate or popcorn calcification. In the hand there may be marked cortical erosion and expansion and still be benign.
Features favoring chondrosarcoma in proximal locations: deep endosteal erosion (about two thirds of cortical thickness), pain, hypercellularity or atypia, and any soft-tissue mass (never present in enchondroma). CT best shows endosteal erosion. Distinguishing benign from malignant cartilage tumors is one of the hardest problems in bone pathology and depends on clinical and radiographic features as much as histology.
Treatment. Observe solitary lesions that are stable and asymptomatic. For growth or symptoms, extended curettage is usually curative, but first exclude other sources of pain (for example a rotator cuff tear in a patient with a proximal humeral lesion).
Ollier disease (multiple enchondromatosis) causes shortening, metaphyseal broadening and bowing; osteotomy can correct deformity. About 25% develop sarcoma by age 40. Maffucci syndrome (with soft-tissue hemangiomas) also has a definite tendency to malignancy. Monitor these patients indefinitely.
Juxtacortical (periosteal) chondromas are small (under 3 cm) surface lesions in a saucer-shaped defect with a sclerotic buttress.
(Campbell)
Osteochondroma
Developmental malformation arising from the periosteum, growing with the patient and usually stopping at skeletal maturity. About 90% are solitary. Common on the distal femur, proximal tibia and proximal humerus metaphyses; may be pedunculated (stalk directed away from the physis) or sessile. Cortex and medulla are continuous with the parent bone, with a cartilage cap that is a few millimeters thick in adults (up to about 2 cm in children).
Complications: mechanical irritation, overlying bursa with loose bodies, fracture, vascular false aneurysm and neuropathy from pressure.
Multiple hereditary exostoses: autosomal dominant, EXT1 or EXT2 mutations, with metaphyseal widening, radial bowing and ulnar shortening; osteotomies may be needed.
Malignant transformation is about 1% for solitary and 5% for multiple lesions in referral series (true rates are lower). Suspect it when a quiet adult lesion grows rapidly; the cap is usually over 2 cm thick, evaluated by CT or MRI, and the tumor is usually a low-grade chondrosarcoma.
Treatment. Observe asymptomatic lesions. Resect (en bloc, removing the entire cartilage cap to avoid recurrence) when the lesion is unsightly, compresses structures or looks malignant.
Subungual exostosis of the distal phalanx (especially the great toe), often after trauma, is excised when nail elevation causes pain.
(Campbell)
Fibrous Lesions
Nonossifying fibroma: developmental metaphyseal defect, up to 20% of children, mostly distal femur, tibia and fibula. Eccentric, lobulated, well-defined with sclerotic scalloped border and no periosteal reaction unless fractured. Most are asymptomatic and regress; fractures are usually treated nonoperatively. Some authors treat lesions larger than 50% of bone diameter, though this is not universally accepted. Biopsy is not warranted. Recurrence after curettage is rare.
Cortical desmoid: irregularity of the posteromedial distal femoral metaphysis in boys 10 to 15 years old, possibly from adductor magnus stress; observe and do not biopsy.
Benign fibrous histiocytoma of bone: histologically like nonossifying fibroma but a true neoplasm, more aggressive, in patients 30 to 40 years old and possibly in the diaphysis or epiphysis. Extended curettage or wide resection is recommended because of local recurrence.
Fibrous dysplasia: replacement of bone and marrow by fibrous tissue and woven spicules, monostotic or polyostotic. McCune-Albright syndrome combines polyostotic disease, cutaneous pigmentation and endocrine abnormalities; Mazabraud syndrome combines it with intramuscular myxomas. Malignant change is extremely rare.
(Campbell)
Complications and Pitfalls
Pathologic fracture, local recurrence after incomplete removal of a nidus or cartilage cap, thermal injury during ablation near skin or neural structures, and missed malignancy when an atypical feature is attributed to a benign lesion. (Campbell)
References
Heck RK Jr, Toy PC. Benign bone tumors and nonneoplastic conditions simulating bone tumors. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Philadelphia: Elsevier; 2026. Chapter 27.