Pathology Low Yield Flashcards
What is the difference between fine needle aspiration and core needle biopsy?
FNA- takes only cytology, used in carcinoma mostly
Core biopsy- cytology and stromal, used mostly in sarcoma
What is important about an open incisional biospy?
1) All contacted tissues are consindered contaminated
2) Avoid exposing neurovascular structures
3) Plan for extensile approach
4) Release tourniquet prior to closure
Describe the MSTS (Enneking) tumor staging system?
System for bengin (1- latent, 2- active, 3- aggressive) and malignant (I-low grade, II-high grade, III-metastatic) that takes into account the site (T1-intracompartmental, T2-extracompartmental) and metastasis (M0 or M1)
1- Non-ossifying fibroma, enchondroma
2- ABC, UBC, chondromblastoma
3- Giant cell tumor
Osteosarcoma most commonly presents as stage IIB (high grade, extracompartmental, M0)
What is the mechanism of action for radiation therapy?
1) production of free radicals
2) Genetic damage
When is radiation therapy used in the setting of orthopedics?
1) Primary bone tumors
- Ewings sarcoma
- Primary lymphoma of bone
- solitary plasmacytoma
2) Adjuvant to soft tissue sarcoma
3) Metastatic bone disease
- Prostate very radisensitive
- Breast 70% sensitive
- GI and renal not radiosensitive
What are some effects of radiation on tissue?
1) Early
- delayed wound healing
- infection
- desquamination
2) Late
- fibrosis
- joint stiffness
- secondary sarcoma (13%)
- fractures (25%)
How do you distinguish telangiectatic osteosarcoma (TO) from aneurysmal bone cyst (ABC)?
1) They have similar radiographs (expansile eccentric lytic lesion with boney septae)
2) both have fluid-fluid levels on MRI; TO has less defined levels
3) Both have lakes of blood on histology; ABC has spindle cells, TO has malignant cells
What are the imaging and histological characteristics of periosteal osteosarcoma?
1) “sunburst” appearance on radiograph, very hot on bone scan
2) histology shows osteoid with chondroblastic matrix (if no osteoid then would be classified as chondrosarcoma)
What is a periosteal chondroma?
Rare benign chondrogenic lesion that occurs on surface of long bones; 10-20 year olds
60% in proximal humerus (also prox and distal femur)
What is the treatment for periosteal chondroma?
If symptomatic; marginal excision with excision of underlying cortex (will recur if cartilage left behind)
What is a chordoma?
Malignant tumor of primitive notochordal origin; 50% recurrence rate after tx; 50% occur in sacrum and coccyx
What are the most common sites for lymphoma of bone?
Pelvis, ribs and spine
What are radiographic and histologic findings in lymphoma?
1) large ill-defined diffuse lytic lesions
2) More common in diaphysis
3) CD20 , CD45 and lymphocyte antigen positive
What is the treatment for lymphoma?
Multi-agent chemo; can use radiation for local disease
What is malignant fibrous histiocytoma?
Similar in presentation to osteosarcoma but does not create osteoid. Rare. Also known as undifferentiated pleomorphic sarcoma
What are imaging and histiologic characteristics of malignant fibrous histiocytoma?
Heterogenous mass on MRI
Metaphyseal destructive lesion
Multinucleated giant cells with mitotic figures, pleomorphic spindle cells
What is the radiologic appearance of a bone infarct?
Medullary lesion of sheet-like central lucency surrounded by sclerosis with a serpiginous border; “smoke up a chimney”
On MRI central lesion will still have normal marrow signal
What is characterized by calcium salt deposits in the extra-capsular soft tissues?
Tumoral calcinosis; more common in women and african-americans in the hip and shoulder joints
What is melorheostosis and how does it appear?
1) Rare benign painful disorder of the extremities characterized by formation of periosteal new bone
2) Looks like “dripping candle wax”
What are the imaging and histiologic appearance of myositis ossificans?
Radiographically, there is peripheral bone formation and central lucency, compared with malignancy which has central bone formation. Histologically, there is mature lamellar bone on the periphery with osteoblastic rimming, and immature fibroblasts in the center. A cartilage component may be present.
What is a benign dysplasia that leads to unilateral varus of the tibia?
Focal fibrocartilagenous dysplasia; majority are seen in toddlers or infants and auto-correct
What is synovial chondromatosis?
A proliferative disease of the synodium associated with cartilage metaplasia that results in multiple intra-articular loose bodies
Most cases of malignant peripheral nerve sheath tumors are associated with what disease?
Neurofibromatosis-1; the tumors are also known as neurofibrosarcoma and malignant schwannoma
What are the histology characteristics of malignant peripheral nerve sheath tumors?
Spindle cells with wavy nuclei; S-100 positive, keratin negative; most are treated with wide resection and radiation
