What are the tumors of bone?
2) Osteoid osteoma/osteoblastoma
What is an osteoma?
Benign bone forming tumor composed of compact or mature trabecular bone --> usually involves facial bones
What is the clinical presentation of a pt with osteoma?
3) Vision changes
Associated with Gardner syndrome (familial colorectal polyposis)
What is the microscopic appearance of an osteoma?
Dense compact bone with paucicellular stroma (see very few cells)
What is Gardner syndrome?
Autosomal dominant (chromosome 5q21 - APC gene) disease leading to multiple colon polyps and tumors in thyroid, bone, epidermoid cysts, fibromas, and desmoid tumors
What are desmoid tumors?
Tumors that grow in b/t muscle fibers and can cause obstruction --> surgical resection causes more tumors to form
What is osteoid osteoma?
Benign tumor of osteoblasts
What population are osteoid osteomas seen in?
Males < 25 years old
What is the clinical presentation of osteoid osteoma?
Bone pain that resolves with aspirin
What is the microscopic appearance of osteoid osteoma?
Randomly interconnected trabeculae of woven bone, prominently rimmed by a single cell layer of osteoblasts
Where do osteoid osteomas occur and what do they look like on imaging?
Cortex of long bones
Bony mass (<2cm) with radiolucent center (osteoid, black arrow) with surrounding sclerosis (white arrow)
How does osteoblastoma differ from osteoid osteoma?
Osteoblastoma usually larger (>2cm)
Bone pain doesn't respond to aspirin
Arise in the vertebrae
What does osteoblastoma look like microscopically?
Comprised of anastomosing trabeculae of osteoid and woven bone rimmed by osteoblasts
How is osteoblastoma treated?
Curettage (scooping) or excision en bloc
What is osteosarcoma?
Malignant prolferation of osteoblasts
What is the epidemiology of osteosarcoma?
Mostly in teenage males
Associated with Pagets disease and post-radiation in elderly
Rb gene = increased risk and poor prognosis
What characteristic feature does osteosarcoma show on imaging?
Codman's triangle --> periosteol reaction to tumor destroying new bone before it ossifies
Indicates aggresive tumor
What does osteosarcoma look like microscopically?
Invades normal bone producing poorly formed bony spicules in a hypercellular matrix of osteoid and numerous pleomorphic malignant cells
Described as "lace-like" --> dainty little tumors
What is seen in chondroblastic osteosarcoma?
Malignant cartilage formation
What is the pathogenesis of osteosarcoma?
70% have acquired genetic mutation
Rb --> germline Rb 1000x increased risk
TP53 --> DNA repair and apoptosis
INK4a --> encodes tumor suppressor
MDM2 and CDK4 --> cell cycle regulators that inhibit p53 and Rb
What are the cartilage-forming tumors?
What is a chondroma?
What are the types of chondroma?
Benign cartilaginous tumor
1) Enchondroma --> arises from diaphyseal medullary cavity
3) Soft tissue chondroma
What genetic mutations are associated with enchondromas?
IDH1 and IDH2 (isocitrate dehydrogenase)
What does a chondroma look like grossly?
Grey-white mass with color consistent with cartilage --> usually well circumscribed
What does chondroma look like microscopically?
Numerous chondrocytes closely packed near periphery in a pink ground substance that resembles normal cartilage
What is an osteochondroma?
Tumor of bone with an overlying cartilage cap --> mushroom cap appearance on X-ray is pathognomonic
What is the epidemiology of osteochondroma?
Mostly in males 10-20 years old
What is the epidemiology and location of enchondroma?
Age 20-49, no gender preference
Usually found in small bones of hands and feet
What is Maffuci syndrome?
Multiple enchondromas and soft tissue hemangiomas; also ovarian carcinoma and brain glioma
What is chondrosarcoma and where is it typically found?
Malignant cartilage forming tumor (no osteoid)
Arises in medulla of pelvis or central/axial skeleton
What is the epidemiology of chondrosarcoma?
Men in their 40s
What is the gross appearance of chondrosarcoma?
Invasive cartilage growth in bone
This example shows cartilage growing across joint space
What is the microscopic appearance of chondrosarcoma?
Cells mimic normal chondrocytes --> appear to float in chondroid-like matrix
What are the fibrous and fibroosseous tumors?
1) Fibrous cortical defect
2) Fibrous dysplasia
What is a fibrous cortical defect (nonossifying fibroma)?
Benign fibrous lesion of bone
What is the epidemiology of fibrous cortical defect?
Children and adolescents
What is the microscopic appearance of fibrous cortical defect?
Fibrous spindle cells with pinwheel appearance
Scattered giant cells, histiocytes, cholesterol clefts, and hemosiderin
What does fibrous cortical defect look like grossly?
Lesion >5cm with intermedullary component
What is fibrous dysplasia?
A problem with osteoblastic maturation that causes fibrous tissue to form instead of medullary bone
How does fibrous dysplasia present and what are the most common sites?
Presents with painful swollen bones prone to fracture
Ribs and femur are most commonly affected
What is the gross appearance of fibrous dysplasia?
Variable size, well circumscribed, medullary, tan-white, gritty mass lesions
What is the microscopic appearance of fibrous dysplasia?
Poorly formed islets of trabeculae of woven bone without a rim of osteoblasts --> resemble chinese characters
Fibroblastic activity surrounding trabeculae with lots of collagen
What is McCune-Albright syndrome?
Fibrous dysplasia plus cafe-au-laite spots and endocrine dysfuntion (especially early onset puberty)
What is a giant cell tumor of bone?
Tumor composed of multinucleated giant cells and stromal cells
What is the epidemiology of giant cell tumor of bone and where does it typically arise?
Young adults (20-40)
Epiphysis of long bones, typically in the knee
What is the characterstic appearance of giant cell tumor on X-ray?
"Soap bubble" appearance --> dude is fucked
What feature of giant cell tumor cells makes them a good candidate for targeted therapy?
High level of RANK-L expression
What is the microscopic appearance of giant cell tumor?
Regular and uniform distribution of stromal and giant cells --> nuclei of mononuclear cells and osteoclasts are ovoid with prominent nucleoli (top pic)
Fibroblastic activity and formation of reactive bone (bottom pic, pink shit)
What is Ewing sarcoma (primitive neuroectodermal tumor)?
Malignant proliferation of poorly-differentiated cells derived from neuroectoderm
What is the epidemiology and typical location of Ewing sarcoma?
Usually in males <15 years old
Typically found in diaphysis of long bones
What is the gross appearance of Ewing sarcoma?
White, fleshy, ill-defined tumor with involvement of medulla and cortex with periosteal elevation
What is the microscopic appearance of Ewing sarcoma?
Sheets of small, round, uniform cells (resemble lymphocytes)
Indistinct cell membranes
What is the characteristic appearance of Ewing sarcoma on X-ray?
Onion skin appearance of periosteum - layered periosteum
What translocation is seen in Ewing sarcoma?
t(11,22) EWS-FLI1 fusion
What cellular organization pattern is sometimes seen in Ewing sarcoma?
Homer Wright rosettes --> dark blue tumor cells surrounding pink fibrillar material resembling neuropil
What is a solitary bone cyst?
Benign lytic lesion, fluid-filled cyst with a thin wall
What is the epidemiology and typical location of solitary bone cysts?
Males <20 years old
Medullary in metaphysis of proximal humerus or femur --> typicaly presents as a fracture
What is an anuerysmal bone cyst?
Exactly what is sounds like asshole
Benign, but grows rapidly
Looks like a sponge filled with blood
What is the epidemiology of anuerysmal bone cysts?
No gender preference; ages 1-20
Removed by curettage
What is the microscopic appearance of anuerysmal bone cysts?
Richly vascularized bone tissue --> differentiating feature is rich capillary bed
What do metastatic bone tumors do to bone? What is the exception?
Produce punched out lesions radiographically
Prostatic carcinoma produces osteoblastic (sclerotic) lesions
What is the mnemonic to remember sites of metastasis for bone shit
BLT with a Kosher Pickle
Whats does metastatic bone tumor from prostatic carcinoma look like radiographically?
Osteoblastic lesions --> highly sclerotic bone