Tumors Of The Bone

Tumours of the Bone – Dr M Schranz

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TUMOURS OF BONE Metastatic Tumours The most common bony malignancies are metastatic carcinomas. Metastatic lesions represent the most common cause of pathology fractures due to a neoplasm. Usually are multiple, but can be solitary. The most common primaries are breast, prostate, lung, kidney and thyroid, in that order. Renal metastasis are quite vascular and have cold bone scans. For example, look at the following plain radiograph of this elderly gentleman with prostatism and pain in the right hip. He had a renal carcinoma which was treated by nephrectomy 8 years before and Paget's disease of the right hemipelvis and proximal right femur known for 20 years.

CT scan of the pelvis (bone window) demonstrates destruction of the anterior cortex with large soft tissue mass.

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A Coronal, gadolinium-enhanced T1-weighted MR-image demonstrates an oval mass in the trochanteric region with intermediate signal intensity on T1-weighted image and strong enhancement after Gd-contrast injection.

Subsequently needle biopsy under CT guidance were carried out, showing metastatic renal carcinoma. Prostate cancer metastases tend to be blastic, that is, they tend to make the bones around them thicker and more dense, whereas many other types of cancer metastasis to the bones tend to be lytic, which means they tend to destroy and remove the bones around them. This means that pathological fractures are relatively uncommon in prostate cancer, and it is likely that a patient with prostate cancer in the spine will not suffer a pathological fracture.

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AP radiograph of the pelvis and the lumbar spine: Multiple circumscribed hyperdense lesions are visible in the lumbar vertebrae and the pelvic bones

Note: Wilms’s tumour and neuroblastoma (rosettes) are the most common metastatic lesions in childhood. Primary Bone Tumours Oesteogenic Lesions Osteoid Osteoma - Usually are intracortical lesions of any bone, especially the femur, tibia, and vertebra (posterior elements), with a characteristic nidus and associated pain. Th e classic pain is worse at night, relieved by salicylates, and exacerbated by alcohol. Treatment ordinarily consists of surgical removal of the nidus with a marginal excision. The following is a plain radiograph of the leg of a 30-year-old man with a complaint of right leg pain of one year's duration. The pain was worse at night but was fully relieved by aspirin. There is no history of trauma.

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A plain radiograph of the right tibia and fibula reveals a focally sclerotic expanded area of the tibial cortex without overlying soft tissue or periosteal abnormalities. A radiolucent nidus is visible in the center of the focal area of sclerosis.

Radionuclide bone scintigraphy using technetium -99m MDP (methylene diphosphonate) reveals a very prominent focal uptake of the radiotracer in the same region seen to be sclerotic on plain radiograph

Three types of osteoid osteomas exist; categories are based on location: ? cortical location is the most common with a dense sclerotic reaction disguising the nidus.

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? Medullary locations, often in the femoral neck or bones of the hands or feet, are less common where osteosclerosis is minimal to moderate. ? Subperiosteal is the rarest form with little or no reactive sclerosis making it a more difficult to diagnose radiographically Osteoblastoma Osteoblastoma is a solitary, benign tumour producing osteoid and bone, with 90% of cases reported in the second and third decades of life. Cases have however been reported in patients aged 3-72 years, this patient being at the lower end of this range. There is a male predominance of 2:1. Clinical symptoms often differ from those of osteoid osteoma, with osteoblastoma producing an inconsistent, dull localized pain, as opposed to the intense nocturnal pain caused by osteoid osteoma. Osteoblastoma of the spine accounts for 30-40% of all osteoblastomas, most frequently involving the posterior vertebral elements (55%), although extension into the vertebral body is common (42%). Approximately 60-70% of osteoblastomas occur in the metaphyses and diaphyses of long bones, and rarely in the pelvis. The following radiograph is of a three year old boy whose mother noticed a reluctance to use his left arm. Plain radiograph of the left shoulder shows eccentric two centimetre oval lytic lesion, with surrounding, well-defined, narrow margin of transition. There is associated lateral metaphyseal periosteal reaction, with no distinct soft tissue component

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Bone scintigraphy (bone scan) shows a focal region of intensely increased activity in the proximal left humeral metaphysis. There is normal distribution of activity in the remainder of the skeleton

The patient underwent an intra-lesional curettage with excision fragments demonstrating nidus formation with islands of osteoid and bone trabeculae lined by osteoblasts, consistent with an osteoblastoma Paget’s Disease This disease, which affects about 3% of men and women, is characterised by increased bony turnover. Paget’s disease typically involves the sacrum, spine, femur and cranium of older patients. Features of Paget’s include deformities (bowing), pain, change in size of bones (increased hat size), kyphosis, and systemic features like cranial nerve impingement, bruits, and high-output cardiac failure. Radiographic features vary with the stage of the disease but include cortical thickening, coarse trabeculae, sclerotic ivory or enlarged picture frame vertebrae, cotton wool appearance of the femur and pelvis, and osteoporosis circumscripta of the calvarium. Paget's disease may result in stress fractures as seen in the tibia below

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Cortical stress fractures as a complication of Paget’s disease are associated with long standing (inactive) disease. The fractures can be partial or complete. Radiographically, they are seen as single or multiple horizontal radiolucent areas with a predilection for the convex aspect of bone. This is in contrast to the Looser’s zones associated with osteomalacia which affect the concave aspect. After Tc 99m were injected, there is markedly intense uptake at the sacrum, left hemipelvis, mid and distal right femur, entire right tibia, proximal and mid left femur. There is expansion of the right distal femur and entire tibia.

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Osteosarcoma The most common primary bone malignancy in children (boys > girls), occurs most commonly in the second and third decades of life. It is characterised by the production of osteoid directly from malignant spindle cell stroma. The knee and proximal humerus are common sites, and early diagnosis is difficult. A relatively painless mass is a frequent presentation. Osteosarcomas are classified as primary or secondary (following a preexisting lesion such as Paget’s or a result of XRT, and usually seen in older patients). Primary tumours are further classified as central or juxtacortical. This osteosarcoma is very dense radiographically, a finding that indicates that the tumor is making bone. The tumor results in the destruction of the adjacent cortex and extends into the adjacent soft tissue.

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Chondrogenic Lesions Chondromas are benign tumours of mature hyaline cartilage usually located within bone (enchondroma), but occasionally on the bony surface (periosteal chondroma). Enchondroma Benign cartilaginous neoplasm arising in diaphyseal medullary cavities of long bones, possibly from epiphyseal plate remnants. Can be solitary or multiple (Ollier’s disease [alone] and Maf fucci’s syndrome [with skin hemangiomata] -

both

with

higher

rates

of

malignant

transformation [up to 30% in Ollier’s]). Enchondromas are asymptomatic and can be located in any bone, especially in the hands and feet. The typical x-ray picture of an enchondroma shows a central, or slightly eccentric, wellcircumscribed or bubbly radiolucent lesion, finely or densely stippled with calcification, and located in the interior of a short or long tubular bone An example of an enchondroma of the humerus:

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Osteochondroma (Osteocartilaginous Exostosis) One of the most common benign bone tumours. These lesions represent a disorder of normal enchondral bone growth, and are usually sessile or pedunculated lesions arising from the cortex of a long bone adjacent to the epiphyseal plate. Tumour enlargement is common and ceases after maturity. The most common location of an osteochondroma is in the region of the knee, particularly the lower metaphysis of the femur or the upper metaphysis of the tibia. The next radiograph shows a typical osteochondroma of the femur.

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An osteochondroma of a long bone characteristically points away from the o j int because its epiphysial site of origin lags behind the advancing growth plate as the bone lengthens Multiple hereditary exostosis is an autosomal dominant disorder with a mild decrease in stature, normal intelligence, and multiple osteochondromas. It is commonly accompanied by leg length discrepancy,

knee

and

elbow

angular

deformities,

and

other

skeletal

abnormalities.

Osteochondromas develop in multiple metaphyses of affected children and they continue to increase in size and number until skeletalmaturity. Problems include nerve compression (especially peroneal nerve), ankle diastasis, angular deformities, and malignant transformation (2%). Chondromyxoid Fibroma Chondromyxoid Fibromas are most commonly found in the metaphysis of a large tubular bone of a lower limb at a variable distance from the frequently open growth plate and often in contact with it. The following image shows an eccentric lytic epiphyseal chondromyxoid fibroma with a scalloped medial internal border.

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Chondroblastoma Chondroblastomas are benign tumors of cartilaginous origin. A characteristic appearance on routine roentgenograms is that of a small, well-defined, round or ovoid, eccentric rarefaction most commonly occupying the end of a long bone. Although predominantly epiphyseal in long bones, the associated growth plate is most commonly open and may be breached by the lesion with resultant metaphyseal extension. Chondroblastoma is a rare benign neoplasm occurring in 75% of cases in the second decade of life, when the growth plates are still open. This is one of two neoplasms of incompletely differentiated cartilage. The other neoplasm is chondromyxoid fibroma. Most common locations are the long bones (70% arise in the proximal humerus and at the knee), and flat bones, including pelvis. In the long bones, the tumor almost invariably occurs in the epiphysis. Conservative treatment of chondroblastoma is usually effective. When this type of lesion involves the impact load bearing bones such as the os calcis treatment is difficult. The tumor, as well as the treatment, weakens the weight bearing integrity of the calcaneus and threatens to violate the heel pad. This can alter gait at heel strike. These considerations are particularly important in athletic individuals.

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This is seen in the next case, a 18 year old male with a complaint of right heel pain that had gradually increased over the two months prior to initial evaluation. Plain radiographs and MRI revealed a well-defined cystic lesion in the posterior inferior aspect of the os calcis

An incisional biopsy was performed, together with curettage of the wall of the cavity, showing the presence of a Chondroblastoma. The cavity was filled with autogenous cancellous bone graft from the right iliac crest; primary closure followed Chondrosarcoma Second to osteosarcoma in prevalence of bony sarcoma’s. Chondrosarcomas can arise from preexisting lesions (osteochondromas, chondromas) or they can be primary. They are usually associated with dull, deep pain. Radiographs may show invasiveness and soft tissue extension. Central chondrosarcoma of femur, shown below, shows a large lesion in the interior of the diaphysis or metaphysis characterized by irregular or circular ( or bubbly) radiolucencies, granular or lobular radioopaque areas of calcification, fuzzy or scalloped regions of destruction of the inner cortex, enlargement of bone contours, focal periosteal reaction, and, most ominously, penetration of the cortex and extension of the tumor into the soft tissue.

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Fibrogenic Lesions Simple (Unicameral) Bone Cyst - Benign lesions that occur during growth. The simple bone cyst is a common, benign, fluid-containing lesion, usually occurring in the metaphysis of long bones Plain radiography is the examination of choice because of its high diagnostic capability of simple bone cysts. CT and MRI usually are not required and should only be used for evaluation in anatomically complex areas such as the spine or pelvis. These areas often are difficult to evaluate accurately on plain film. Use CT and MRI to determine the extent of the lesion and whether complications such as a fracture are present. Nuclear medicine scans usually are not necessary in the evaluation of simple bone cysts. Radiographs demonstrate simple bone cysts as well-defined, geographic lesions with narrow transition zones. A thin sclerotic margin is a typical finding. Simple bone cysts usually are situated in the intramedullary metaphyseal region immediately adjacent to the physis. A pathologic fracture through a simple bone cyst is a common occurrence. This may lead to the ‘fallen fragment’ sign, which describes the migration of a fragment of bone to a dependent portion of the fluid-filled cyst. It occurs in only a minority of patients. This sign is an important differentiating feature between a simple bone cyst and other nonlytic bone lesions. When present, the ‘fallen fragment’ sign is pathognomonic of a simple bone cyst. A 10-year -old boy with a simple bone cyst in the upper metaphyseal region of the right humerus. A pathologic fracture is noted. A ‘fallen fragment’ is observed within the lesion (arrow). This sign is pathognomonic of a simple bone cyst.

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Aneurysmal Bone Cyst (ABC). Aneurysmal bone cyst is a rare, solitary, expansive vascular lesion most often located in the long bones, vertebrae, or flat bones and most frequently seen between 5-20 years Radiographically, aneurysmal bone cyst of a long bone is a radiolucent lesion, usually eccentrically located in the metaphysis and often with a characteristic subperiosteal "blow out" appearance. Radiograph showing an aneurysmal bone cyst of the tibia.

Fibrous Dysplasia Fibrous dysplasia is also common the in skull, ribs, and tibia. Radiographs also show a typical ground glass appearance and scalloping from within.

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On CT scan an expansile lesion is seen in a right lower rib exhibits several benign features: sharp margins, no aggressive periosteal reaction, and no associated soft tissue mass. No cartiliginous tumor matrix is evident.

Nonossifying Fibroma (Fibrous Cortical Defect) Nonossifying Fibroma is the most common bone lesion (40% children); - it results from defect of periosteal cortical bone development which leads to failure of ossification. The lesion typically is a well marginated radiolucent lesion, with a distinct multilocular appearance. The lesion is usually irregular and is surrounded by a reactive rim of bone. Typically you should see benign cortical thinning, erosion, slight expansion. Look at the following CT , it shows a bony lesion that is mostly sclerotic. It has a sharp zone of transition, no periosteal reaction, no matrix formation, and lies in the medullary portion of the bone, adjacent to the lateral cortex. This radiographic appearance strongly suggests a benign lesion. Entities to consider would include a healing fibrous cortical defect and fibrous dysplasia

Haematopoietic Lesions Eosinophilic granuloma

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Eosinophilic granuloma (EG) is a solitary, non-neoplastic proliferation of histiocytes. EG is part of a spectrum of Langerhan's cell histiocytosis, formerly known as histiocytosis X. EG is a localized lesion in bone or lung and occurs most commonly in children aged 5 to 10. The radiologic appearance of EG is non-specific and differs by location. The skull may have a lesion with sharp, punched out borders that is uneven across the inner and outer table causing a "beveled edge". Pelvic lesions are often poorly defined. Spine lesions are normally found in the vertebral body. EG is found in the diaphysis or metaphysis of long bones in the center of the medullary cavity. The lesion may cause endosteal scalloping or a periosteal reaction. Bone scan is not useful in defining EG. CT scan and MRI delineate the extent of the intramedullary and cortical penetration. The radiologic differential includes Ewing's sarcoma, osteosarcoma, metastases and osteomyelitis. lesion in the diaphysis of the tibia showing in the center of the medullary cavity. The lesion may cause endosteal scalloping

Myeloma - Uncontrolled proliferation of marrow plasma cells (highly differentiated B lymphocytes) leads to the development of this tumour, the most common primary malignant tumour in bone. Common presentations include bone pain, anaemia and raised ESR in a 50-60 year old patient. Histology demonstrates sheets of plasma cells (clock faced eccentric nuclei, perinuclear clear area, and

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increased RER on electron microscopy). Of note, the lesion lacks any background stroma. X-ray shows punched out lesions. Treatment is chemotherapy, radiotherapy and surgical stabilisation impending fractures. The following shows a vertebral body biopsy of a lesion under CT guidance, performed by Dr Viktor Serafimov in the Radiology Department. The patient had severe back pain and the lesion was seen was seen on the plain film. A scintigraphy suprisingly showed an increase in the signal intensity of this lesion. This turned out to be multiple myeloma on histology.

Lymphoma of Bone (Histiocytic Lymphoma) Primary lymphoma of bone (PLB) is a rare malignant neoplastic disorder that affects the skeleton. Most PLB cases result from non– Hodgkin-type lymphoma PLB has been reported in patients as young as 2 years and as old as 88 years. The incidence of disease is distributed fairly evenly in the second through eighth decades The most common radiographic features include the following ?

Permeative lytic pattern of bone destruction (74%)

?

Metadiaphyseal location (69%)

?

Periosteal reaction (58%)

?

Soft tissue mass

The following shows a lateral radiograph demonstrating a lytic lesion with a moth-eaten appearance centered in the mid diaphysis of the tibia.

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Typical scintigraphic appearance. Whole body image from technetium 99m bone scan reveals a solitary area of intensely increased tracer uptake suggestive of Paget disease. An old left rib fracture and degenerative changes in both hands are evident.

Undetermined Etiology Giant Cell Tumour The majority of these tumours present between 20 - 40 yrs and only 3% are found in the immature skeleton. The usual sites are in the bones adjacent to the knee, distal end of radius and occasionally in the sacrum or pelvis. The probability of a particular bone tumour location is often related to the relatively greater normal bone growth in that area. With large tumours, the site of origin is inferred from the centre of radius of the mass. The osteoclastoma is related to an apophysis or joint margin. The cyst like lesion is lobulated, which gives a pseudo- multiloculate appearance on a plain radiograph. The lesion is typically asymmetrically placed in the bone. The endosteal margin is not usually sclerotic and can often be hazy. A wider endosteal margin usually means a more aggresive tumour with a greater possibility of recurrence after curetting. There is thinning of the

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overlying cortex from the expanding lesion. The cortex may be so thinned as to be unseen and this impression of a soft tissue mass is not necessarily an indication of sarcoma. There is no periosteal reaction associated with this tumour. The tumour has a vascular character and shows an increased blood pool phase of the bone scan. The following radiograph shows an osteoclastoma (giant cell tumour) in the distal ulna

Ewing’s Sarcoma Second (to osteosarcoma) most common malignant bone tumour of childhood. Occurs in young children in the flat and axial bones (pelvis), and in the diaphyses of long bones (fibula, femur). Often associated with systemic signs (fever, weight loss) and local tenderness with erythema and induration, and can be confused with osteomyelitis. The radiographic findings of Ewing's reflect its pathologic course. Early on, as the lesion displaces the marrow elements with only modest bone destruction, it appears a splotchy, permeative, ill-defined radiolucent process with indistinct margins and a rather wide zone of transition to normal bone In this magnified view of the proximal humerus with a Ewing's in the metaphysis, there is early reactive bone about the medial and lateral cortices.

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With continued enlargement, the lesion extends through the reactive new bone that the periosteum is laying down in an attempt to contain the lesion. This extension results in the development of a large soft-tissue component. This often destroys the periosteal reaction over the central portion of the lesion leaving Codman's triangles of reactive bone proximally and distally.

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The following table indicates the commonest locations of bone tumours.

LOCATION/SITE

TYPICAL PATHOLOGY Chondroblastoma, chondrosarcoma, giant

Epiphyseal cell tumour, infection Metaphyseal

Any lesion Osteoblastoma,

Diaphyseal

Ewing’s

eosinophilic

granuloma,

adamantinoma, fibrous dysplasia

Pelvis

Mets, myeloma, Ewing’s, chondrosarcoma, Paget’s Disease.

Proximal humerus

Chondroid lesions.

Knee

Osteosarcoma, adamantinoma, chondromyxoid fibroma

Ribs

Mets, myeloma, Ewing’s chondrosarcoma, fibrous dysplasia

Spine (Vertebral body) Spine

lymphoma,

(Posterior

elements) Periosteal Multiple lesions

Mets,

myeloma,

eosinophilic

granuloma,

chondroma,

Paget’s,

haemangioma Aneurysmal bone cyst, osteoid osteoma, osteoblastoma

Myosotis, osteosarcoma, chondrosarcoma, chondroma Mets, myeloma, haemangioma, fibrous dysplasia, osteochondromas, enchondromas, histiocytosis X

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