Chondroblastoma
Epidemiology and Etiology:
- Skeletally immature
patients
- M > F
-
Common sites:
- epiphysis
(concomitant involvement of metaphysis commonly
- long bones (>70%)
- distal and
proximal femur
- proximal tibia
- proximal humerus
- flat bones
- talus
- calcaneus
- patella
Gross features:
- almost invariably
solitary
- small (3-6cm)
- occupying less
than half of the epiphysis typically
- tan with white
areas
- may be partly
cystic
- X-ray:
- Lytic typically
- Sharply demarcated
- +/- thin sclerotic
border
- no expansion of
bone or periosteal reaction usually
- matrix
calcifications (1/3)
Histologic features:
- pseudo-lobulated sheets
- remarkably uniform
cells (chondroblasts)
- round to
polygonal
- well defined cytoplasmic borders
- clear to
slightly eosinophilic cytoplasm
- round to ovoid /
reniform nucleus
- clefts
or longitudinal grooves often
- one
or more inconspicuous nucleoli
- cytological atypia may be seen
- large,
hyperchromatic nuclei
- scattered osteoclast-type giant cells almost always present
- chondroid accompanying chondroblasts
- poorly-formed
hyaline cartilage
- variably sized nodules
of light-staining, amorphous, bluish to eosinophilic
material
- mature hyaline
cartilage is uncommon
- “chicken-wire”
calcification often
- fine network of pericellular calcification
- mitoses common
- regional necrosis
is common
- aneurismal bone
cyst-like changes may be seen
Immunophenotype:
|
Marker:
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Sensitivity:
|
Specificity:
|
|
S100
|
|
|
|
Vimentin
|
|
|
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CK
|
often
|
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Molecular features:
- diploid usually
- structural
abnormalities involving chromosomes 5 and 8 in some
- 8q21
rearrangements in aggressive lesions
Other features:
- 80-90% cured by
curettage
- 14-18% local
recurrence rates
- pulmonary mets rarely (can be managed by resection/observation)
- EM:
- deep nuclear
indentations
- Abundant rough
ER
- Long cytoplasmic processes
References: