BONE PATHOLOGY

CHAPTER 7 BONE PATHOLOGY



Bone tumors

Introduction

Osteochondroma

Enchondroma

Chondroblastoma

Chondrosarcoma

Chondromyxoid fibroma

Synovial chondromatosis

Osteoid osteoma

Osteoblastoma

Osteosarcoma

Desmoplastic fibroma of bone

Fibrosarcoma of bone

Benign fibrous histiocytoma of bone

Malignant fibrous histiocytoma of bone

Ewing’s sarcoma (see also PNET)

Giant cell tumor of bone

Chordoma

Adamantinoma

Aneurysmal bone cyst

Simple bone cyst

Fibrous dysplasia of bone

Osteofibrous dysplasia

Langerhans cell disease

Erdheim–chester disease

Chest wall hamartoma of infancy

Non-tumor pediatric osteoarticular disease

Arthritis

Osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO)

Osteopetrosis

Myositis ossificans

Ganglion cyst


BONE TUMORS



INTRODUCTION



• In many countries, including the UK, bone tumors are diagnosed and managed by specialist tertiary centers

• In most cases the diagnosis is suspected from clinical and imaging data and hence biopsies and resection specimens will be dealt with by specialist bone tumor centers
image the appropriate handling, blocking and sectioning of such specimens requires specialist equipment and expertise

• Therefore, this section will only briefly cover the main points of entities which may be encountered in a diagnostic pediatric pathology practice and more specialist texts on bone pathology should be consulted

• In general, malignant pediatric bone tumors affect the long bones and include predominantly
image osteosarcomas
– affecting mainly metaphyses of patients in the second decade

image Ewing sarcoma
– affecting mainly diaphyses of similar aged patients

image a range of other pediatric malignancies may metastasize to bone and a bone lesion in a patient under 5 years of age is statistically more likely to be metastatic

• Most bone tumors are not associated with an underlying predisposing factor but a range of associations are reported
image Ollier disease

image Maffuci syndrome

image familial retinoblastoma syndrome

image Rothmund–Thomson syndrome

image multiple osteochondromas

image Paget’s disease of bone

image post-radiation

image other rare entities

• Bone tumors generally present with:
image pain

image swelling

image loss of function

image pathological fracture

• Radiological imaging is essential for adequate interpretation of the histopathological features, in particular:
image the site
– specific bone

– diaphysis vs metaphysis vs epiphysis

image size

image position
– central vs eccentric

image invasiveness and soft tissue involvement

image periosteal reaction

image isolated vs multiple lesions

• In surgical pathology material bone tumors are graded on the basis of cellularity and nuclear features
image see specialist texts for discussion and specific details


OSTEOCHONDROMA



Epidemiology



• First three decades
image common in children

• 15% are multiple

• Malignant transformation in <1%
image increased risk in multiple


Clinical features



• Asymptomatic, painless bony lesion

• Metaphysis of long bones of limbs


Histopathological features (Fig 7.1)



• Pedunculated lesion with cartilage cap and extension of medulla into lesion

• Outer perichondrium

• Underlying cartilage

• Underlying bone

• Endochondral ossification

• No atypia

• Well organized structure

image

Fig 7.1 Photomicrograph of a benign osteochondroma, demonstrating a well-organized structure with a cartilage cap overlying the medullary cavity.



Differential diagnoses and pitfalls



• Myxoid change, atypia, fibrous bands and disorganization may indicate malignant transformation


ENCHONDROMA



Epidemiology



• Common

• Most often present in adults
image children also affected


Clinical features



• Tubular bones
image mainly hands and feet

• Painless swellings

• Pathological fractures


Histopathological features (Fig 7.2)



• Multinodular, intramedullary well-circumscribed cartilage nodules

• Hyaline cartilage matrix

• Bland chondrocytes
image small round nuclei

• May show myxoid change

• No mitoses or atypia

• Normal marrow between nodules

image

Fig 7.2 Photograph of a benign enchondroma in a patient with Maffuci syndrome, demonstrating a nodular lesion composed of mature cartilage.



Differential diagnoses and pitfalls



Periosteal chondroma



• On bone surface
image arises from periosteum

• Long bones
image especially humerus

• Cartilage nodules do not penetrate underlying cortex


Enchondromatosis



• Ollier disease
image multiple enchondromas in childhood

• Maffuci syndrome
image also has vascular lesions of soft tissue
– especially cavernous hemangiomas

• Increased risk of chondrosarcoma
image develops in adulthood


CHONDROBLASTOMA



Epidemiology



• 10–25 years

• M > F


Clinical features



• Mainly long bones epiphyses

• Painful

• Local recurrence 10–20%


Histopathological features (Figs 7.3, 7.4)



• Lesion composed of chondroblasts
image uniform round to ovoid cells

image clear to eosinophilic cytoplasm

image nuclear grooves
– ‘coffee bean’ nuclei

• Scattered osteoclast-like giant cells

• Immature chondroid stroma

• Pericellular ‘chicken wire’ calcification

• Scattered slightly atypical nuclei are normal variant

image

Fig. 7.3


image

Figs 7.3–7.4 Photomicrographs of a chondroblastoma, demonstrating a lesion composed of chondroblasts with areas of immature chondroid stroma and scattered osteoclast-like giant cells.



Differential diagnoses and pitfalls



• Non-progressive lung ‘metastases’ reported in association with benign chondroblastomas


CHONDROSARCOMA



• Malignant mesenchymal tumor with hyaline differentiation


Epidemiology



• Mainly adults
image children reported


Clinical features



• Pelvis, long bones, hands and feet, head and neck (Gadwal et al 2000)

• Swelling, pain


Histopathological features (Figs 7.5–7.6)



• Chondroid matrix

• Lobules of cartilage
image hypercellular

image atypical chondrocytes
– hyperchromatic

– enlarged

– binucleate

– mitoses

image myxoid change

image necrosis

• Grades I–III (grade predicts prognosis)

image

Fig. 7.5


image

Figs 7.5–7.6 Photomicrographs of chondrosarcomas, confirmed on specialist review, demonstrating infiltrating lesions composed of lobules of cartilage with chondroid matrix and atypical chondrocytes.



Periosteal chondrosarcoma



• similar features but in periosteal location


Mesenchymal chondrosarcoma



• Younger age
image usually young adults

• Malignant behavior but long clinical course

• Craniofacial, ribs, vertebrae

• Biphasic pattern
image areas of undifferentiated small round cells
– similar to other SRBCTs

image nodules of hyaline cartilage


Clear cell chondrosarcoma



• Mainly adults
image adolescents also

• Epiphyses of long bones
image mainly humerus and femur

• Lobules of clear cells with distinct membranes

• Focal chondroid differentiation


Immunohistochemical staining



• S100+ in chondroid areas

• SRBCTs of mesenchymal chondrosarcoma are CD99+


Differential diagnoses and pitfalls



• Caution in diagnosing chondrosarcoma in childhood
image rare

• Caution in diagnosing chondrosarcoma in lesions of hands and feet
image in these sites enchondromas may also be hypercellular, binucleate

• Secondary chondrosarcomas develop in benign enchondroma or osteochondroma
image especially Ollier / Maffuci syndromes

• development of increased cellularity and atypia


CHONDROMYXOID FIBROMA



Epidemiology



• Rare

• M > F

• Usually 10–30 years


Clinical features



• Any site
image mainly long bones

• Pain and swelling

• Metaphyseal eccentric lucent lesion

• 15% recurrence


Histopathological features



• Well-demarcated lesions

• Microlobular pattern

• Myxoid stroma

• Stellate and spindle cells
image alternating microscopic cellular and hypocellular areas

• Pleomorphism 20–30%

• Rare mitoses
image not atypical

• With or without cartilage and calcification

• ABC like areas 10%


Immunohistochemical staining



• S100+

• Peripheral cells may be SMA+, CD34+


SYNOVIAL CHONDROMATOSIS



Epidemiology



• Usually adults
image children reported


Clinical features



• Joints
image usually knee

• Pain, swelling, locking, mass


Histopathological features



• Nodules of hyaline cartilage
image variably cellular

• Fibrous outer layer

• With or without synovium and ossification


OSTEOID OSTEOMA



Epidemiology



• Usually children

• M > F


Genetics



• Possible 17q loss
image not in diagnostic use


Clinical features



• Any site
image mainly long bones

• Pain
image especially at night

image relieved by NSAIDS

• Tender

• Swelling

• Well circumscribed cortical lesion
image associated with cortical sclerosis on radiology


Histopathological features



• <2 cm diameter

• Central connective tissue with osteoid
image forming bony trabeculae

image prominent osteoblasts

• Cartilage not usually present

• Hypervascular peripheral sclerotic bone


OSTEOBLASTOMA



Epidemiology



• Usually 10–30 years

• M > F


Clinical features



• Spine and sacrum, limbs and other sites

• Mainly medullary
image rare periosteal

image cementoblastoma in jaw

• Pain

• Swelling

• Local mechanical effects

• Lytic lesion with reactive periosteal shell

• May have ABC-like areas


Histopathological features (Figs 7.7, 7.8)



• >2cm diameter

• Well circumscribed, pushing margin

• Morphologically mimics osteoid osteoma
image randomly arranged central bony trabeculae

image covered by osteoblasts

• Vascular stroma
image ABC-like areas

image

Fig. 7.7


image

Figs 7.7–7.8 Photomicrographs of osteoblastomas, demonstrating randomly arranged bony trabeculae covered by osteoblasts.



Differential diagnoses and pitfalls

Related posts:

  1. METABOLIC DISEASE PATHOLOGY
  2. HEAD AND NECK PATHOLOGY
  3. RENAL PATHOLOGY
  4. TUMORS AND TUMOR-LIKE LESIONS

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Jun 18, 2016 | Posted by in PEDIATRICS | Comments Off on BONE PATHOLOGY

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