< Back Basic Tumor Biology Overview of tumour biology including cellular... Tumour biology encompasses the study of how neoplastic cells proliferate, evade apoptosis, promote angiogenesis, and invade surrounding tissues. The tumour microenvironment — including stromal cells, immune cells, and vasculature — plays a key role in supporting tumour progression. Key molecular pathways include p53 suppression, Rb inactivation, and overexpression of growth factor signalling. Understanding these mechanisms is crucial for developing targeted therapies. Previous Next

< Back Dr. Ahmet Müçteba YILDIRIM Enchondroma Overview • Enchondroma is a benign hyaline cartilage tumor, accounting for 20-25% of benign bone tumors. • It arises from residual cartilage cells that fail to undergo necrosis after physeal growth. • Can be solitary or multiple (Ollier’s disease, Maffucci syndrome). Clinical Presentation Often asymptomatic, detected incidentally (except in hand lesions). Hand enchondromas: Pain due to bone expansion, cortical thinning, or microfractures. Long bone enchondromas with pain: Rule out first intra-articular pathologies, atypical cartilage tumor or chondrosarcoma Associated Syndromes Ollier’s disease: Multiple enchondromas, unilateral, 20-50% malignant transformation risk. Lesions are generally unilateral. Short stature, limb length discrepancy, and angular deformities in bones and joints are commonly seen. Maffucci syndrome: Enchondromas + soft tissue hemangiomas; higher malignancy risk than Ollier’s. Due to phleboliths, hemangiomas are also detected on X-rays. Common Sites Hands (40-65%): Proximal phalanges > metacarpals > middle phalanges. Long bones: Femur, humerus, tibia (metaphyseal). Rare in carpal/tarsal bones or distal phalanges. Imaging Features X-ray: Hands: Lytic, sclerotic rim, bone expansion, cortical thinning, calcification is not usually seen. Long bones: Metaphyseal, indistinct margins, endosteal scalloping, matrix calcification. CT: Evaluates calcification and cortical integrity. MRI: Assesses soft tissue extension, peritumoral edema, contrast enhancement (for differential diagnosis) and fat entrapment. PET-CT: Useful for enchondromatosis/pelvic lesions Biopsy Not routine; reserved for atypical features (e.g., pain, growth, or imaging suspicious for chondrosarcoma). Target less calcified, fat entrapment and heterogeneous areas on MRI. Biopsy tract should align with potential surgical incision. Treatment Asymptomatic, small (<4 cm), stable lesions: Annual monitoring.(BACTIP Protocole* : Birmingham Atypical Cartilage Tumor Imaging Protocol) Surgical indications: Pain, growth on follow-up, or pathologic fracture risk. Techniques: Intralesional curettage + adjuvant + bone-filler (PMMA/graft) ± fixation (fracture risk in lower extremities). Hand lesions: Curettage alone/ Curettage and bone filler (PMMA/Graft) Differential Diagnosis Atypical Cartilage Tumor (ACT): WHO 2020 reclassified grade I chondrosarcomas in extremities as ACT (no metastasis risk but can recur). Suspect if pain, size >4 cm, generalized endosteal scalloping. Chondrosarcoma: Cortical destruction, soft tissue involvement, axial skeleton location. Type Tumor Length Endosteal Scalloping Management 1a <4 cm None Discharge 1b <4 cm Focal Follow-up in 3 years; refer to oncology or discharge based on changes 1c <4 cm Generalized Immediate oncology referral 2a ≥4 cm None Follow-up in 3 years; refer to oncology or discharge based on changes 2b ≥4 cm Focal Follow-up at 1 & 3 years; refer to oncology or discharge 2c ≥4 cm Generalized Immediate oncology referral 3 any size Aggressive features Immediate oncology referral The Birmingham Atypical Cartilage Tumor Imaging Protocol (BACTIB) classification Previous Next

< Back Biopsy Principles Safe biopsy techniques are essential to prevent tumour spread and avoid compromising future surgery. A biopsy is a critical step in diagnosing musculoskeletal tumours and must be carefully planned: Always perform after imaging to avoid artefact and misdiagnosis. Performed by the surgeon or in consultation with the surgical team who will do the definitive surgery. Prefer longitudinal incisions along planned resection paths. Avoid contaminating multiple tissue planes or neurovascular bundles. Needle (core) biopsy is preferred in most cases due to lower morbidity and comparable diagnostic yield. Open biopsy is reserved for cases with inadequate needle sampling. Biopsy tract must be resected en bloc during definitive tumour surgery.Poorly performed biopsies may upstage the disease or preclude limb salvage. Previous Next

< Back Fibrous Dysplasia Fibrous Dysplasia is a benign intramedullary fibro-osseous lesion where normal bone is replaced by immature woven bone and fibrous stroma, resulting in structural weakness and deformity. Fibrous dysplasia can present as monostotic (single bone) or polyostotic (multiple bones) involvement. The monostotic form is more common and often affects the ribs, femur, tibia, or craniofacial bones. It typically appears in children and young adults and may be discovered incidentally or present with pain, swelling, deformity (e.g., shepherd’s crook deformity in the femur), or pathologic fractures. Radiographs reveal a characteristic “ground-glass” appearance with cortical thinning and bone expansion. Histologically, the lesion consists of irregular trabeculae of woven bone ("Chinese characters") without osteoblastic rimming. Treatment is usually conservative for asymptomatic cases. Surgical intervention (e.g., curettage, grafting, internal fixation) is considered for symptomatic lesions or deformity. Fibrous dysplasia can be associated with McCune-Albright syndrome (with café-au-lait spots and endocrine abnormalities) in polyostotic forms. Previous Next

< Back Philosophy of Oncological Orthopaedics Oncological orthopaedics is guided by principles that prioritise patient-centred care, limb preservation, and multidisciplinary collaboration, with an emphasis on tumour control and functional outcomes. Main Content : The core philosophy is to achieve local tumour control while maximising quality of life.Multidisciplinary team (MDT) involvement—including orthopaedic surgeons, oncologists, radiologists, and pathologists—is essential in planning and executing treatment.Function-preserving surgery is preferred when oncologically safe. Limb salvage is prioritised, provided clear margins are achievable without compromising prognosis.Treatment goals should align with the patient’s values , prognosis, and systemic disease status.Emphasis is placed on evidence-based practice , surgical precision, and integrating emerging modalities like navigation, 3D planning, and personalised implants.Palliative considerations should not be overlooked in advanced cases—surgery can still provide meaningful pain relief and mobility. Previous Next

< Back Non-Ossifying Fibroma (NOF) Non-ossifying fibroma (NOF) is a benign, non-osteogenic bone lesion composed of fibroblastic cells, typically located in the metaphysis of long bones during childhood and adolescence. It is usually asymptomatic and detected incidentally on radiographs obtained for other reasons. 1.Synonyms Fibrous cortical defect (for smaller lesions) Metaphyseal fibrous defect Fibroxanthoma Nonosteogenic fibroma Fibrous histiocytoma of bone Sometimes confused with “cortical desmoid” (different localization) 2. Associated Conditions / Syndromes NOF can be an isolated finding but may also be associated with certain systemic syndromes: Neurofibromatosis type 1 (NF1) Jaffe-Campanacci syndrome: Multiple NOFs + café-au-lait macules + mental retardation + hypogonadism + cardiac anomalies 3. Epidemiology Age: Common between 5–20 years Sex: Slight male predominance (~1.6:1) Prevalence: Seen radiographically in 30–40% of children Most frequent locations: Distal femur, proximal tibia, distal tibia, proximal fibula 4. Pathogenesis and Genetics Previously thought to be a reactive process; current DNA analyses have revealed KRAS , FGFR1 , and NF1 mutations → suggesting a neoplastic process related to RAS-MAPK pathway activation. Typically eccentric in location, adjacent to the cortex. 5. Clinical Features Usually asymptomatic Large lesions : Mechanical weakness → risk of pathological fracture May cause pain Diagnosis is often facilitated if a pathological fracture is present 6. Imaging Radiograph : Eccentric, metaphyseal, cortically based, well-defined, lobulated radiolucent lesion with internal septations Often 1–3 cm (fibrous cortical defect) or larger (NOF) CT : Demonstrates cortical thinning and intracortical location MRI : Hyperintense on T2; hypointense on T1 if hemosiderin present Periosteal reaction is typically absent 7. Histology Gross : Well-circumscribed, soft, yellow-brown fibrous tissue Cut surface may show small foci of hemorrhage and hemosiderin deposits Microscopic : Well-vascularized fibrous stroma with haphazardly arranged spindle-shaped fibroblasts Interspersed lipid-laden foam cells (xanthomatous histiocytes) Focal multinucleated giant cells Frequent hemosiderin pigment deposition Minimal cellular atypia, rare mitotic figures Occasional ossification or bone trabeculae within fibrous stroma Sclerotic bony rim may be present at the periphery Differential Diagnosis : Aneurysmal bone cyst, fibrous dysplasia, giant cell tumor 8. Treatment and Natural History Small/asymptomatic : Observation (most regress and sclerose spontaneously by late adolescence) Large/high fracture risk : Curettage + bone grafting Prophylactic fixation may be considered Recurrence after surgery is rare NOF at proximal tibia (lateral view) NOF at proximal tibia (AP view) Previous Next

< Back Endoprosthesis Endoprosthetic reconstruction is a widely used limb-salvage technique after bone tumor resection. It provides structural and functional restoration, especially in the femur and humerus. Main Content : Endoprostheses are custom or modular implants used to replace resected bone and adjacent joints after oncologic resections. They allow for immediate weight-bearing and have become the standard of care in selected patients with good soft tissue coverage and expected long-term survival. Complications include infection, loosening, and mechanical failure. Previous Next

< Back Primary Bone Lymphoma A rare lymphoma subtype presenting primarily in bone, often mimicking other primary bone tumours. Main Text: Primary bone lymphoma (PBL) is a rare form of extranodal non-Hodgkin lymphoma that originates in the bone without initial lymph node involvement. The most common histological subtype is diffuse large B-cell lymphoma (DLBCL). PBL frequently involves long bones like the femur, pelvis, or spine and typically presents with pain, swelling, or a pathologic fracture. Radiographically, it may appear as a lytic or permeative lesion with periosteal reaction, mimicking Ewing sarcoma or osteomyelitis. Diagnosis is confirmed via biopsy and immunohistochemistry (e.g., CD20+, BCL6+, MUM1+ in DLBCL). Treatment includes systemic chemotherapy (usually R-CHOP regimen) and often radiotherapy. Surgical intervention is limited to stabilization of fractures or biopsy. Prognosis is generally favourable compared to other primary bone malignancies, especially with early diagnosis and treatment. Previous Next

< Back Adjuvant Therapies (Chemo, RT) Adjuvant therapies such as chemotherapy and radiotherapy are critical components of multidisciplinary oncological treatment, enhancing tumour control and improving survival in various musculoskeletal malignancies. Main Content : Chemotherapy is essential in the management of high-grade sarcomas, particularly osteosarcoma and Ewing sarcoma. Neoadjuvant chemotherapy (pre-operative) helps reduce tumour size, facilitates surgical resection, and provides early systemic control. Adjuvant (post-operative) chemotherapy targets micrometastatic disease. Common agents include doxorubicin, cisplatin, methotrexate, and ifosfamide.Radiotherapy is frequently used in radiosensitive tumours like Ewing sarcoma, lymphoma, and some soft tissue sarcomas. It can be employed as a definitive, neoadjuvant, adjuvant, or palliative modality. Advances such as IMRT and proton therapy allow for more precise dose delivery with reduced collateral damage.Proper timing, sequencing, and coordination with surgery are vital. Complications such as wound healing delays, fibrosis, and secondary malignancies must be considered. Previous Next

< Back Unicameral Bone Cyst (UBC) Unicameral bone cyst (UBC) is a benign, fluid-filled intramedullary lesion typically located in the metaphysis or diaphysis of long bones in children and adolescents. It is usually unilocular and adjacent to the cortex. Pathological fracture is the most common presentation. 1.Associated Conditions UBC may coexist with other lesions: Secondary aneurysmal bone cyst (ABC) Fibrous dysplasia Post-infectious cystic lesions Post-traumatic intramedullary cysts 2. Epidemiology Age: 5–15 years Sex: More common in males (~2:1) Most common sites: Proximal humerus (50–60%), proximal femur (25–30%) Rarely in other long bones, pelvis, or calcaneus 3. Pathogenesis The exact etiology is unclear; proposed mechanisms include intramedullary circulation disturbance and venous obstruction, leading to increased intramedullary pressure and cyst formation. Persistent fluid communication with the growth plate is seen in some cases. 4. Clinical Features Usually asymptomatic Most often presents with pathological fracture Pain typically related to fracture Cortical thinning in large cysts may cause deformity 5. Imaging Radiograph : Metaphyseal or diaphyseal intramedullary location Unilocular, well-defined, homogeneous radiolucency Marked cortical thinning “Fallen fragment sign” (bone fragment within cyst after fracture) CT : Shows cyst wall and cortical thinning MRI : T2 hyperintense fluid; thin cyst wall; septa are uncommon 6. Histology Gross : Thin-walled, unilocular, fluid-filled cyst Lined by fibrous tissue; inner surface smooth Microscopic : Thin cyst wall of fibrovascular connective tissue Sparse fibroblasts, macrophages, and foam cells within wall Hemosiderin deposits and cholesterol clefts may be present Variable inflammatory cell infiltrate Occasional new bone trabeculae within wall Differential Diagnosis : Aneurysmal bone cyst, intraosseous ganglion, fibrous dysplasia 7. Treatment and Natural History Small/asymptomatic : Observation Large/high fracture risk : Minimally invasive: Steroid injection, bone marrow aspirate injection Surgical: Curettage + bone graft ± internal fixation Recurrence rate: 10–30%; follow-up until growth plate closure recommended AP view of UBC , proximal humerus Falling leaf sign Previous Next

< Back Osteochondroma Osteochondroma is the most common benign bone tumor, typically arising from the metaphysis of long bones during skeletal growth. Osteochondroma is a cartilage-capped bony outgrowth projecting from the surface of a bone, commonly found near the growth plates of long bones. It usually presents in adolescence and may be solitary or part of multiple hereditary exostoses (MHE). Though benign, it may cause pain or neurovascular compression and rarely transform into chondrosarcoma. Previous Next

< Back Imaging Principles Core imaging modalities and interpretation strategies in orthopaedic oncology. Imaging plays a pivotal role in the diagnosis, staging, and surgical planning of bone and soft tissue tumours. The essential modalities include: Plain Radiographs : First-line; provides information on lesion location, bone destruction, periosteal reaction, matrix mineralisation. MRI : Gold standard for local staging; defines tumour extent, soft tissue involvement, neurovascular relationships. CT : Useful for cortical bone evaluation and chest staging for metastases. Bone Scintigraphy : Assesses multifocal involvement and occult metastasis. PET/CT : Functional imaging to evaluate metabolic activity and response to therapy.Cross-sectional imaging must be done before biopsy to avoid artefact and guide safe sampling. Previous Next