epidemiology of unicameral (simple) bone cyst
common lesion found in kids
occasionally in adults
location of unicameral (simple) bone cyst
centrally located in the bone (medullary canal)
usually metaphyseal
presentation of unicameral (simple) bone cyst
usually presents with fracture
no known risk factors
treatment of unicameral (simple) bone cyst
observation
steroid injection
BM injection
curettage / grafting
**30% recurrence with any treatment, likely due to underlying vascular abnormality
goal is to keep kids achieving their developmental milestones
appearance of unicameral (simple) bone cyst on xray
sharp distinction
lytic areas of fluid / blood
ground glass area where lytic lesions healed
unicameral (simple) bone cyst on histo
spindle cells
open spaces
no necrosis / mitotic activity
epidemiology of osteoid osteoma
teens and early 20s
M:F = 2:1
location of osteoid osteoma
< 2 cm appendicular skeleton (femur or tibia 50%)
symptoms of osteoid osteoma
painful
excess PGE2 produced by proliferating osteoblasts (causes swelling within bone, leading to pain)
pain relieved by aspirin ( can be used long term)
treatment of osteoid osteoma
radiofrequency ablation
appearance of osteoid osteoma on xray
active bone around lesion
presence of nidus within lesion
osteoid osteoma on histo
nidus surrounded by reactive bone
spindles in background
osteoblastic rimming
presentation of osteoid osteoma in the spine
painful scoliosis
lesion on concave side of spinal curve
-PGE causes contraction of muscles
appearance of osteochondroma on xray
sharp transition
medullary canal of bone contiguous with medullary canal of lesion
cortex of bone contiguous with cortex of lesion
appearance of osteochondroma on CT
bone present behind cartilage cap on lesion
reactive bone
appearance of osteochondroma on histo
looks like a physes, but less organized
cartilage cap on reactive bone
what is an osteochondroma
exostosis
benign cartilage capped outgrowth that is attached to the skeleton by a bony stalk
hereditary osteochondromas genetics
multiple hereditary exostosis (multiple osteochondromas)
EXT1 and EXT2 mutations
solitary osteochondromas genetics
85% EXT1 mutation
what is the EXT gene
in growth plate chondrocytes
prognosis / treatment of osteochondroma
1% risk of transformation to chondrosarcoma per lesion
multiple lesions increases risk
don’t usually remove unless symptomatic
periosteal chondroma location
sits on the surface of bone
arises in only one bone (don’t need to look for other lesions)
arises from cambium layer of periosteum
treatment of periosteal chondroma
usually resected due to risk of enlargement
periosteal chondroma on imaging
intact cortex with mineralized lesion on top
periosteal chondroma on histo
more cellular than a lesion within bone
has lacunae with cartilage and matrix and fibrous tissue
presentation of enchondroma
frequently presents in hand after fracture
radiographically and histologically more aggressive in the hand
treatment of enchondroma
usually surgical intervention in the hand
intervention not necessary in other locations unless concern about more aggressive lesion
-follow for increasing lytic component (growth without mineralization)
appearance of enchondroma on histo
less matrix and more cellularity than normal cartilage
histologically inactive
appearance of enchondroma on xray
popcorn areas within bone
typical location of enchondromas
usually solitary
metaphyseal region
develop from rests of growth plate cartilage
syndromes associated with enchondromas
Ollier’s disease- multiple enchondromas
Maffucci syndrome - enchondromatosis + soft tissue hemangiomas
-increased risk of malignancy in all body parts, unrelated to lesions
prognosis of enchondromas
small risk (<1% per lesion) of malignancy transformation
location of chondroblastoma
epiphyseal or apophyseal (next to growth plates)
epidemiology of chondroblastoma
occurs in adolescents
presentation of chondroblastoma
presents with acute onset of pain and swelling of the adjacent joint
similar to an infected joint
evaluation of chondroblastoma
should be urgent, to not miss infected joint and to provide pain relief
MRI and labs can help rule out infection
treatment of chondroblastoma
biopsy
curettage
grafting
differentiation of low grade liposarcoma from lipoma
slightly more cellular
presence of lipoblasts
MDM2 increased in liposarcoma (test done after excision)
treatment of lipomas
not all need to be removed
if consistent with fat on MRI, can be watched if less than 5 cm in greatest dimension and are not enlarging
assessment of lipoma
assess for ring chromosome or MDM2 amplification (proto-oncogene amplified in liposarcomas)
second most common soft tissue sarcoma
liposarcoma
appearance of fibromatosis on xray
indentation in bone due to pressure effect of soft tissue mass
histo appearance of fibromatosis
sheets of spindle cells and collagen
characteristics of fibromatosis
benign but locally aggressive
no ability to metastasize
usually in response to trauma (injury response that doesn’t turn off)
may respond to estrogen (BCP can make it bigger)
hardest lesion that you’ll palpate, usually fixed
epidemiology of fibromatosis
slightly higher incidence in women
treatment of extra-abdominal desmoid
confirm diagnosis (vs low grade fibrosarcoma)
if symptomatic or enlarging, resect with wide margins
avoid amputation
amputation may be required if limb is at risk
non surgical treatment of extra abdominal desmoid
variable course, may regress
responds to RT
possible use of SERMs or chemo for unresectable but symptomatic lesions
what is an undifferentiated pleomorphic sarcoma
most common type of soft tissue sarcoma
unknown tissue type
epidemiology of UPS
occurs in middle aged to older adults
screening of UPS
CT of chest, as with all sarcomas
treatment of UPS
radiation and surgical resection (wide margin)
chemo if at risk of spread or has metastasis
features of UPS on histo
large cells with mitotic activity
spindle cells
clumping