Laboratory Studies
General Screening
- CBC, renal profile, coagulation profile, LFT
Infection Markers
- ESR, CRP -Z
Metabolic Panel
- Calcium & phosphate, alkaline phosphatase, PTH; brown tumour
Metastatic Workup
- Additional specific tests as indicated
Biopsy
Types of Biopsy
-
Fine Needle Aspiration (FNA)
- Not used for sarcoma
-
Core Needle Biopsy (Tru-cut)
- Allows for tumor structural examination
- Evaluates cytologic and stromal elements
- Frequently used for sarcoma diagnosis
- Allows for tumor structural examination
-
Incisional Biopsy
- Small surgical incision carefully placed
- Accesses tumor without contaminating critical structures
-
Excisional Biopsy
- Used for small, superficial soft tissue masses
Indications for Biopsy
- Aggressive or malignant appearing bone or soft tissue lesions
- Soft tissue lesions >5cm, deep to fascia, or overlying bone/neurovascular structures
- Unclear diagnosis in symptomatic patient
Contraindications for Biopsy
- Asymptomatic bone lesion that appears entirely benign on imaging
- Benign-appearing soft tissue lesion on MRI (lipoma, hemangioma)
- When in doubt, it is safer to perform a biopsy
Diagnostic Approach: Key Questions
1. Patient Age Assessment
- >40 years - higher suspicion for metastasis or myeloma
- 20-40 years (skeletal mature) - wide differential
- <20 years (skeletal immature) - primary bone tumors more common
2. X-Ray Features Analysis
- Benign vs aggressive appearance
- Matrix characteristics (cartilaginous, osseous, fibrous)
3. Lesion Location
- Intra-articular
- Epiphyseal
- Metaphyseal
- Diaphyseal
4. Diagnostic Spectrum
- Benign lesions
- Metastatic vs primary bone tumor (osteosarcoma vs chondrosarcoma vs Ewing)
- Metabolic bone disease (brown tumor, Paget disease)
- Osteomyelitis (local tumor-like condition)
Tumor Classification #±
Bone Forming Tumors
Benign Lesions
- Osteoma
- Enostosis (bone island)
- Osteoid osteoma
- Osteoblastoma
Malignant Tumors
- Osteosarcoma
- Extraskeletal osteosarcoma
Cartilage Forming Tumors (Chondrogenic Lesions)
Benign Lesions
- Enchondroma
- Periosteal chondroma
- Osteochondroma
- Chondroblastoma
- Chondromyxoid fibroma
Malignant Lesions
- Chondrosarcoma
Fibrous Lesions
Benign Lesions
- Fibrous cortical defect
- Fibrous dysplasia
- Osteofibrous dysplasia
Malignant Tumors
- Malignant Fibrous Histiocytoma (MFH)
Tumor-Like Lesions
Benign Lesions
- Giant cell tumor (GCT)
- Simple bone cyst
- Aneurysmal Bone Cyst (ABC)
- Intraosseous lipoma
Malignant Tumor
- Adamantinoma (usually on tibial chin)
Most Common Tumors by CategoryY
| Category | Most Common Tumor(s) |
|---|---|
| Soft tissue tumor (children) | Hemangioma |
| Soft tissue tumor (adults) | Lipoma |
| Malignant soft tissue (children) | Rhabdomyosarcoma |
| Malignant soft tissue (adults) | Malignant fibrous histiocytoma |
| Primary benign bone tumor | Osteochondroma |
| Primary malignant bone tumor | Osteosarcoma |
| Secondary benign lesion | Aneurysmal bone cyst |
| Secondary malignancies | Metastases, MFH, Fibrosarcoma |
| Phalangeal tumor | Enchondroma |
| Sarcoma of hand/wrist | Epithelioid sarcoma |
| Sarcoma of foot/ankle | Synovial sarcoma |
Differential Diagnosis by AgeY
| Age Range | Malignant Lesions | Benign Lesions |
|---|---|---|
| Birth to 5 yr | Leukemia, Metastatic neuroblastoma, Rhabdomyosarcoma | Osteomyelitis, Osteofibrous dysplasia |
| 10-25 yr | Osteosarcoma, Ewing tumor, Leukemia | EG, Osteomyelitis, Enchondroma, Fibrous dysplasia |
| 40-80 yr | Metastases, Myeloma, Lymphoma, Chondrosarcoma, MFH | Hyperparathyroidism, Paget disease, Enchondroma |
Differential Diagnosis by Anatomical Location
Common Lesions by SiteY
| Location | Common Lesions |
|---|---|
| Skull | Eosinophilic granuloma, Metastases, Myeloma |
| Mandible | Adamantinoma, Dentogenic cysts |
| Humerus | Wide variety, Simple bone cyst |
| Ribs | Metastases, Enchondroma, Chondrosarcoma, Ewing sarcoma |
| Spine | Metastases, Myeloma, Osteoblastoma, Chordoma, Hemangioma, ABC, Osteoid osteoma |
| Pelvis | Osteosarcoma, Chondrosarcoma, SBC, Lymphoma, Ewing, EG, Chordoma |
| Distal radius | Giant cell tumor, Eosinophilic granuloma |
| Hands | Enchondroma |
| Proximal femur | SBC, Fibrous dysplasia, Enchondroma, Ewing, EG |
| Around knee | All types, especially Osteosarcoma, Ewing sarcoma |
| Tibia shaft | NOF, Fibrous dysplasia, Adamantinoma, Osteoid osteoma |
| Calcaneus | SBC, Ewing, Osteoblastoma, Chondroblastoma |
| Y | |
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