Bony Swellings

Classification

1. Inflammatory / Infective

• Acute osteomyelitis
• Chronic pyogenic osteomyelitis
• Brodie's abscess
• Tuberculous osteomyelitis
• Syphilitic osteomyelitis / periostitis

2. Neoplastic - Benign

3. Neoplastic - Malignant (Primary)

4. Neoplastic - Secondary (Metastatic)

• Common primaries: thyroid, kidney, lung, prostate, breast (mnemonic: TK-LPB)
• Typically in patients >40 yr
• Bone metastases from thyroid and renal carcinoma can be pulsatile

5. Developmental / Dysplastic

• Diaphyseal aclasis (hereditary multiple exostoses)
• Fibrous dysplasia - diffuse, painless bony swelling with facial deformity; does not cross the midline; "ground glass" on X-ray
• Paget's disease of bone

6. Metabolic / Endocrine

• Generalized osteitis fibrosa (hyperparathyroidism)
• Rickets

Site Localisation (Key Diagnostic Clue)

• Epiphysis: Giant cell tumor (osteoclastoma)
• Metaphysis: Osteomyelitis, Brodie's abscess, tuberculous osteomyelitis, bone cyst, osteoma, osteosarcoma, osteochondroma
• Diaphysis: Ewing's tumor, multiple myeloma, syphilitic osteomyelitis
• (S Das: A Manual on Clinical Surgery, p. 153)

Clinical Examination of a Bony Swelling

Inspection

• Site and relation to the bone/joint
• Size, shape, skin changes, surface veins, sinuses

Palpation - Key Features

• (S Das: A Manual on Clinical Surgery, p. 153)

Important Specific Conditions

Osteochondroma (Most Common Benign Bone Tumor)

• Bony excrescence with a cartilage cap at the metaphysis of long bones
• Pedunculated or sessile
• Ceases to grow after epiphyseal fusion
• Rarely undergoes sarcomatous change (multiple exostoses have higher risk)
• X-ray: bony outgrowth with continuity of medullary canal

Osteoid Osteoma

• <2 cm; cortex of femur or tibia; young men
• Severe nocturnal pain relieved by aspirin/NSAIDs (prostaglandin E2-mediated)
• X-ray: thick rim of reactive cortical bone; central nidus

Giant Cell Tumor (Osteoclastoma)

• Epiphysis of long bones; 20-40 yr
• Locally aggressive (can recur after curettage)
• X-ray: eccentric lytic lesion, "soap bubble" appearance
• Egg-shell crackling on palpation

Osteosarcoma

• Most common primary malignant bone tumor in young people
• Metaphysis of distal femur and proximal tibia; 10-20 yr
• X-ray: Codman's triangle (periosteal elevation), sunburst appearance
• Variable consistency on palpation - a diagnostic feature
• Metastasizes to lungs

Ewing Sarcoma

• Diaphysis; 5-20 yr
• X-ray: "onion-skin" periosteal reaction
• Small round blue cells histologically
• Aggressive; treated with chemo + surgery/radiation

Multiple Myeloma

• Most common primary malignancy of bone in adults (>65 yr)
• Punched-out lytic lesions, diffuse osteoporosis
• Back pain + ESR >100 mm/h = myeloma until proven otherwise
• Diagnosis: monoclonal gammopathy, elevated urinary Bence Jones proteins

Assessment - Three-Phase Approach

• (Bailey & Love's Short Practice of Surgery 28th Ed, p. 611)

Investigations

• Plain X-ray of whole bone (most informative for primary bone tumors)
• Ultrasound (soft-tissue component)
• MRI (extent, soft-tissue invasion, skip lesions)
• CT (cortical destruction, calcification pattern)

• FBC, ESR, serum calcium, urea & electrolytes, bone profile, protein electrophoresis
• CT chest (lung metastases - mandatory for sarcomas)
• Whole-body bone scan
• Urine for Bence Jones proteins (myeloma)
• ALP: raised in osteosarcoma and Paget's disease

• Leucocytosis: osteomyelitis
• Raised serum calcium + raised gamma-globulin: multiple myeloma
• Raised serum calcium: hyperparathyroidism, generalized osteolysis
• ESR >100 mm/h + back pain: multiple myeloma
• Raised ALP: osteosarcoma, Paget's
• (S Das: A Manual on Clinical Surgery, p. 155)

Red Flags for Malignancy (Refer to Specialist)

• Night pain / non-mechanical pain (especially in young adolescent)
• Mass >5 cm
• Increasing in size
• Deep to deep fascia
• Recurrence after previous excision
• History of prior malignancy + bone lesion = metastatic until proven otherwise

Key Radiological Patterns

Examination of a Bone Swelling

A. HISTORY

• Age - narrows the differential significantly (see site/age table below)
• Duration and rate of growth - slow = benign; rapid = malignant/inflammatory
• Pain - nature, timing
  • Night pain in a young adolescent → primary bone tumor until proven otherwise
  • Nocturnal pain relieved by aspirin/NSAIDs → osteoid osteoma (prostaglandin E2-mediated)
  • Non-mechanical pain → malignancy
• History of prior malignancy - bone metastasis must be excluded
• Constitutional symptoms - fever, weight loss, evening rise of temperature (TB)
• Other swellings in the body - multiple myeloma, diaphyseal aclasis, generalized osteitis fibrosa involve >1 bone

B. LOCAL EXAMINATION

INSPECTION

• All bony swellings are fixed to the bone

Dilated subcutaneous veins overlying an osteosarcoma (S Das, Manual on Clinical Surgery)

• Oedema → venous compression by the bony swelling
• Paresis/palsy → nerve involvement (e.g., foot drop from osteoma at head of fibula)

• Sympathetic effusion of an adjacent joint → acute osteomyelitis
• Deformity (genu valgum/varum, manus valgus) → asymmetric epiphyseal destruction from osteomyelitis
• Deformed joints also seen in diaphyseal aclasis

PALPATION

• Raised in: acute pyogenic osteomyelitis, osteosarcoma

• Inflammatory swellings: always tender
• Tumours: generally non-tender (important distinction)

• Diffuse, margins hard to define (extreme pain/tenderness) → inflammatory swelling
• Pedunculated → exostosis (osteochondroma)
• Spherical, ovoid, irregular → tumour of bone

• Smooth, lobulated → benign growth
• Irregular → malignant growth or chronic infection

• Ill-defined → inflammatory swelling
• Well-defined → new growth
• Note: osteosarcoma is rapidly growing → loses its well-defined edge

• Pulsatile bony swellings:
  • Telangiectatic osteosarcoma
  • Aneurysmal bone cyst
  • Highly vascular osteoclastoma (occasionally)
  • Haemangioma of bone (very rarely)
  • Highly vascular metastatic carcinoma from thyroid and renal adenocarcinoma

• Irregular bone surface on careful palpation → chronic pyogenic osteomyelitis, syphilitic osteomyelitis, tuberculous osteomyelitis, Brodie's abscess

• Hold the base of the ulcer/sinus and move it against the bone - if fixed to bone → bone is the source
• Determine if sequestrum is present at depth (sprouting granulation tissue in the sinus mouth)

C. GENERAL EXAMINATION

• Tuberculous osteomyelitis: Look for pulmonary TB (cough, haemoptysis, evening fever), cervical/axillary/inguinal lymphadenopathy
• Syphilitic osteitis: Look for syphilitic stigmata, elicit contact history
• Osteomyelitis: Search for primary infective foci - skin, teeth, tonsils, ear, sinuses
• Multiple myeloma, diaphyseal aclasis, generalized osteitis fibrosa: Ask for other bony swellings elsewhere in the body
• Secondary carcinoma: Examine for primary in thyroid, kidneys, lungs, prostate, breast, uterus, GIT, testis

D. SPECIAL INVESTIGATIONS

Blood

Urine

• Albuminuria → amyloid disease from long-continued suppuration (osteomyelitis)
• Bence Jones protein (coagulates at 55°C, dissolves at 80°C, reappears on cooling) → multiple myeloma (present in ~50% of cases); also skeletal carcinomatosis, leukaemia

X-Ray Examination (Most Important Special Investigation)

Note: Secondary carcinoma is not detectable on X-ray until at least 50% of the medullary bone is destroyed. Bone scan/MRI are more sensitive.

Other Imaging

• MRI - extent of tumor, soft-tissue invasion, skip/satellite lesions (mandatory before any biopsy)
• CT chest - lung metastases
• Bone scan - whole-body survey for metastatic deposits
• Ultrasound abdomen - renal primary (lytic bone lesion can be renal metastasis)

Biopsy

• Definitive diagnosis
• Should be done at a specialist centre
• Needle/open biopsy depending on site and clinical context