My Clinical Notes

Metastatic bone tumours

 

• Commonest form of skeletal malignancy
• Are generally carcinomas
• In adults, 80% can be accounted for by the following primaries;
  • Breast
  • Bronchus
  • Prostate
  • Thyroid
  • Kidney
• In children the following cause bone secondaries;
  • Neuroblastoma
  • Wilms tumour
  • Ewing’s tumour
  • Rhabdomyosarcoma
• Most deposits cause osteolysis but prostate can cause osteosclerosis, they do this by stimulating either osteoclasts or osteoblasts
• Most common cause of hypercalcaemia in the middle aged and elderly
• Generally multifocal but kidney and thyroid can produce solitary lesions
• May occur in any bone but most involve the axial skeleton, femur and humerus
• Metastases to small bones of the hands and feet are uncommon and generally originate from cancers of the kidney, lung or colon
• Frequent cause of pathological fractures
• Pathways of metastatic spread include;
  • Direct extension
  • Lymphatic of haematogenous dissemination
  • Intraspinal seeding (Batson plexus of veins)

 

Primary bone tumours

 

• Uncommon – account for 0.5% of cancer deaths
• Predisposing factors;
  • Paget’s disease
  • Fibrous dysplasia
  • Exposure to ionising radiation
• Can present with pain (all the time), swelling, a lump, lymphadenopathy
• Do an x-ray, MRI, bone scan
• Biopsy can be open or closed
• Can be divided into;
  • Bone forming
  • Cartilage forming
  • Fibrous and fibro-osseous
  • Miscellaneous

 

• Most common benign primary bone tumours
  • Osteochondroma
  • Chondroma
• Most common malignant primary bone tumours (after those of bone marrow origin)
  • Osteosarcoma (20% of primary bone cancers)
  • Chondrosarcoma
  • Ewing’s tumour

 

• Staging – via the Enneking grading
  • 1 – low grade
  • 2- high grade
  • 3- mets
    • site – a - intracompartmental
    •          b - extracompartmental

 

Bone forming tumour

 

1)      OSTEOMA

 

·        Affects middle aged

·        Painless, dense overgrowth of cortical bone particularly in skull and mandible

·        Affects flat bones of jaw, skull and face

·        Generally solitary but can be multiple when associated with Gardner’s syndrome (mutations in APC result in intestinal polyps, epidermal cysts, fibromatosis and osteomas)

·        Generally slow growing but can obstruct the sinuses, impinge brain or eye or cause problems with the oral cavity

 

2) OSTEOID OSTEOMA

 

• Mainly affects males between 10-30
• Less than 2cm in dimension
• Can develop in any bone but generally involves the appendicular skeleton – femur and tibia
• Causes pain at rest which is dramatically relieved by asprin as the pain is caused by release of PGE2 by osteoblasts. Pain disproportionate for the small size
• On x-ray they are well circumscribed lesions with sclerosis around a small lucent nidus
• Treated by resection

 

3) OSTEOBLASTOMA

 

• Looks the same histologically as osteoid osteoma but is bigger (>2cm)
• Can occur at any age but is more common in male teens
• More commonly affects the spine
• The pain is dull and achy and doesn’t respond to asprin
• On x-ray it produces a lucent  defect surrounded by active bone
• Treated by resection, can reoccur if not fully removed

 

4) OSTEOSARCOMA

 

• Malignant mesenchymal tumour in which the cancerous cells produce bone matrix
• Obeys Phemister’s law which states where there is growing bone you are more likely to get a tumour. Therefore occur in the metaphyseal region of long bones
• More commonly occur around knee
• 10-20% will have lung mets at presentation
• Most occurs in male teens
• 25% occur in the elderly and are associated with Pagets disease, bone infarct and ionising radiation
• Patients with hereditary retinoblastoma are 1000 times more likely to develop osteosarcoma – attributed to mutations in Rb
• Fatal if untreated, now 75% with early disease survive
• Morphology
  • Bulky tumours which can have haemorrhagic and cystic inclusions
  • Frequently produce soft tissue masses
  • Spread extensively in the medullary canal
  • May penetrate epiphyseal plate and enter the joint
  • Generally spindle shaped neoplasms
  • Produce osteoid (characteristic)
  • Radiologically there is a ‘sunray’ speculation around the bone and lifting of the periosteum (Codman’s triangle). Patchy osteolysis and osteosclerosis.
• Additional subtypes;
  • Parosteal osteosarcoma
  • Periosteal osteosarcoma
  • Telangiectatic

 

 

Cartilage – forming tumours

 

1) OSTEOCHONDROMA (EXOTOSIS)

 

• Benign cartilage capped out growth, attached to the underlying skeleton by a bony stalk
• Common
• Can be solitary or multiple
• Solitary osteochondromas are diagnosed in early adulthood M>F
• Develop in bones only of endochrondral origin and arise in the metaphysis of long bones, especially around the knee
• Morphology
  • Range in size from 1cm to 20 cm
  • Cap is composed of hyaline cartilage and is surrounded by perichondrium
  • Medullary cavity is in continuity with that of the bone
• Generally present as slow growing masses which can cause pain if the impinge on a nerve or the stalk gets fractured
• Patients with multiple hereditary exostosis have a mutation in the EXT gene (autosomal dominant) and develop multiple osteochondromas. They are at higher risk of developing an oestosarcoma

 

2)      CHONDROMA

• Benign tumours of the hyaline cartilage arising from remnants of epiphyseal pain
• If they arise from the medullary cavity they are called endochondromas (most common)
• If they arise from the surface of the bone they are called (sub)periosteal chondromas
• Cause pain, fracture and deformity
• Endochondromas can be solitary or multiple
• Located in the metaphyseal area of tubular bones – hands, feet, humerus and femur
• Multiple endochondromas or endochondromatosis is called Ollier disease
• If endochondromatosis is associated with tissue hemangiomas it is called Maffucci syndrome (also at risk of ovarian tumours and gliomas)
• Morphology
  • Small, nodular configuration
  • At the periphery of the nodules the cartilage can ossify and the centre can calcify and die
  • On x-ray they consist of well circumscribed lesions confined to the medulla – O ring sign
• Periosteal chondromas are rare and usually involve the proximal humerus and distal femar

 

3)      CHONDROBLASTOMA

 

• Rare cartilaginous tumour in teens M>F
• Predilection for epiphyses
• Most arise near the knee and the small bones of feet
• Clinically very painful and because of their location can cause effusions and restrict mobility
• Well circumscribed and radio-lucent on x-ray
• Morphology
  • Very cellular, composed of sheets of polyhedral chondroblasts
  • Hyaline matrix calcifies producing a ‘chicken-wire’ pattern of mineralization
  • Scattered throughout the lesion are osteoclast-type giant cells

 

4)      CHONDROMYXOID FIBROMA

 

• Rarest cartilage tumour – can be mistaken for a chondrosarcoma
• Affect young adults M>F
• Tumours arise most frequently from the metaphysis of tubular bones – around knee and bones of foot
• Patients complain of dull localised pain
• Radiolucent on x-ray with adjacent sclerosis of cortex
• Occasionally tumour can expand the surrounding cortex
• Morphology
  • Well circumscribed and glistening
  • Composed of poorly organised hyaline cartilage
  • Greatest cellularity at the peripheries

 

5)      CHONDROSARCOMA

 

• Produce neoplastic cartilage
• Commonly arise secondary to benign cartilage tumours
• Patient >40, M>F
• Commonly arise in the central portions of the skeleton – rarely involves distal extremities
• Present as painful, rapidly progressive lumps
• Radiologically scalloping is seen  and bone destruction – foci of flocculent density
• Preferentially metastase to lungs and skeleton
• Morphology
  • Composed of malignant hyaline or myxoid cartilage
  • Central necrosis may result in cystic spaces
  • Tumour can push into the surrounding soft tissues
  • Malignant cartilage infiltrates the marrow space
  • Prognosis depends on the grade and whether it was resected completely during initial stages

 

Fibrous and fibro-osseous tumours

 

• Tumours composed predominantly of fibrous elements are diverse and include some of the most common lesions of the skeleton

 

1) FIBROUS CORTICAL DEFECT/NONOSSIFYING FIBROMA

 

• Common, found in almost have of children over age 2
• Believed to be developmental defects rather than neoplasms
• Most arise from the metaphysis of the distal femur or proximal tibia
• Can be bilateral or multiple
• If they are greater than 5cm they are called non-ossifying fibroma
• Generally asymptomatic and spontaneously resolve although the ones that develop into non-ossifying fibromas may present with pathological fracture
• Morphology
  • Produce elongated sharply demarcated radiolucencies that are surrounded by a thin layer of sclerosis
  • Cellularly consist of fibroblasts and activated macrophages (Histiocytes)
  • Fibroblasts are arranged in a storiform pattern (pinwheel)
  • Histocytes may be present as giant cells or clusters of foamy macrophages

 

2) FIBROUS DYSPLASIA

 

• Rare and benign of fibro-osseous tissue. All the components of normal bone are present but in an immature form
• Can result in 3 clinical patterns;
  • Monostotic – involvement of a single bone
  • Polyostotic – involvement of several bones
  • McCune-Albright Syndrome – polyostotic disease associated with café au lait spots and endocrine abnormalities – due to G-protein mutation and excess cAMP
• Monostotic lesions account for 70% of cases
  • Affects males and female in early adolescence and often stops growing at the time of growth plate closure
  • Can cause enlargement and torsion of the bone and if craniofacial bones are involved, disfigurement
• Polyostotic disease without endocrine changes results in 27% of cases
  • Manifests earlier than monostotic disease and can continue into adulthood
  • Can cause crippling deformities and spontaneous and recurrent fractures
  • Small risk of development of malignancy
• McCune-Albright syndrome is associated with sexual precocity, hyperthyroidism, GH secreting pituitary adenomas an adrenal hyperplasia
  • Bone lesions are generally unilateral and café au lait spots affect the same side and are large and irregular
• Morphology
  • Well circumscribed
  • Trabeculae look like Chinese writing

 

3) FIBROSARCOMA/MALIGNANT FIBROUS HISTIOCYTOMA

 

• Fibroblastic collagen producing tumours of the bone
• Difficult to distinguish between the two
• Mostly affect middle aged and elderly
• Fibrosarcoma M=F
• Malignant histiocytoma M>F
• Present as painful enlarging masses usually arising at the metaphysic of long bones and pelvic flat bones. Often develop pathological fractures
• Radiologically lytic and penetrate into soft tissue
• High grade tumours have a poor prognosis

 

 

Miscellaneous tumours

 

1) EWING SARCOMA

 

• Peripheral primitive neuroectodermal tumour. Histologically if lesion shows neuroectodermal differentiation it is called a Primitive Neuroectodermal tumour (PNET) and if it is undifferentiated it is called a Ewing sarcoma
• Accounts for 5-10% of primary bone tumours and typically affect children and young adults M>F. Whites more commonly affected than blacks
• Can affect all bones and patients present with localised pain and swelling and possibly pathological fractures
• Most commonly femur, pelvis, tibia, humerus and ribs
• Usually are at the diaphysis of long bones – site is tender, warm and swollen and may mimic infection
• Due to a 11-22 chromosome gene translocation which act as a dominant oncogene
• X-rays show a lytic destructive lesion that extends into the soft tissues with a distinctive periosteal reaction called onion-skinning
• Morphology
  • Arise from medulla and invade the cortex and periosteum producing a soft tissue mass
  • Contains areas of haemorrhage and necrosis
  • Tumour cells are arranged in circles with a central fibrillary space called Homer-Wright rosettes

 

2) Giant cell tumour

 

• Also called an osteoclastoma as it contains a profusion of multinucleated oestoclast giant cells
• Are believed to be of macrophage-monocyte lineage
• Relatively benign but very aggressive locally
• Arises in the epiphyses of adult (age 20-30) long bones F>M
• Majority arise around the knee – patients can complain of arthritic symptoms an can present as pathological fractures
• Radiologically they are large and lytic and can erode into the subchondral bone plate
• Can metastase to lungs
• Morphology
  • Frequently undergo cystic degeneration
  • Osteocytic giant cells can have up to 100 nuclei
  • Secondary features include haemorrhage, necrosis, reactive bone formation and hemosiderin deposition
  • Required to be distinguished from the brown tumour seen in hyperparathyroidism

 

3) Myeloma

 

• Affects middle aged and elderly M>F
• Causes 1% of cancer deaths
• Can be multiple or solitary (plasmacytoma)
• Plasmacytomas can progress to multiple myelomas
• Monoclonal proliferation of bone marrow plasma cells
• Widespread osteolytic lesions, bone pain, hypercalcaemia, monoclonal gammopathy and amyloidosis
• Complications include recurrent infections due to abnormal immunoglobulin suppression
• Hyperviscosity syndrome
• Renal insufficiency
• Neuropathy can result due to infiltration of nerve root trunks

 

 

 

 

 

This entry was posted on Friday, November 9th, 2007 at 12:40 pm and is filed under Orthopaedics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.