Bone and Soft Tissue Pathology I, II and III Flashcards
(93 cards)
1
Q
What components make up bone tissue?
A
extracellular matrix and specialized cells (osteoblasts, osteocytes, osteoclasts)
2
Q
What are the two parts of the bone matrix and their proportions?
A
- Organic part (1/3): Osteoid (type I collagen, GAGs, proteins)
- Inorganic part (2/3): Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂]
3
Q
What are the functions of osteoblasts?
A
found on the bone surface and they synthesize, transport, assemble bone matrix, and regulate mineralization
4
Q
What are osteocytes and where are they located?
A
mature osteoblasts trapped in lacunae; they maintain bone and communicate via canaliculi
5
Q
What do osteoclasts do?
A
multinucleated macrophages on bone surfaces that resorb bone
6
Q
What is endochondral ossification and what bones form this way?
A
Bone replaces a cartilage model → forms long bones (e.g. femur)
7
Q
What is intramembranous ossification and what bones form this way?
A
Bone forms directly from mesenchyme (no cartilage) → forms flat bones (e.g. skull, clavicle)
8
Q
What is woven bone and when is it produced?
A
Rapidly formed, disorganized, more cellular bone; seen in embryogenesis and fracture healing
9
Q
What is lamellar bone?
A
Mature bone with organized collagen layers that replaces woven bone
10
Q
What is a Haversian system (osteon)?
A
A column of concentric lamellae surrounding a Haversian canal with blood vessels, nerves, and lymphatics
11
Q
What connects Haversian canals together?
A
Volkmann’s canals, which run perpendicular to osteons
12
Q
How are osteocytes formed from osteoblasts?
A
Osteoblasts secrete matrix → get trapped in lacunae → become osteocytes
13
Q
How do osteocytes communicate?
A
Via canaliculi, which are small connecting channels
14
Q
What are the major regions of a long bone?
A
Epiphysis: End
Physis: Growth plate
Metaphysis: Between epiphysis and diaphysis
Diaphysis: Shaft (middle portion)
15
Q
What is the difference between cortical and cancellous bone?
A
- Cortical (compact): Dense, found at bone periphery
- Cancellous (spongy): Porous, in the interior near epiphyses
16
Q
What are the first steps in evaluating a bone lesion radiologically?
A
Determine if the lesion is single or multiple, and whether it’s focal or diffuse
17
Q
What six locations should be assessed if the lesion is focal and what features should be assessed after lesion location is identified?
A
- Epiphysis
- Physis
- Metaphysis
- Diaphysis
- Cortex
- Medulla
- Margins (well vs. ill-defined), matrix (bone/cartilage/fibrous content) and periosteal reaction (none, lamellated, sunburst, Codman’s triangle)
18
Q
What is the cortex and medulla in bone anatomy?
A
- cortex: dense, outer layer of bone (peripheral)
- medulla: central marrow cavity (inner part of bone).
19
Q
What characterizes a Type 1A, 1B and 1C lytic lesion?
A
- 1A: Geographic destruction with well-defined sclerotic margin; suggests benign, slow-growing lesion
- 1B: Geographic destruction with well-defined non-sclerotic margin; likely benign but more active
- 1C: Geographic destruction with an ill-defined margin; suggests aggressive or malignant process
20
Q
What does a sclerotic margin indicate in a lytic lesion?
A
host bone is attempting to wall off the lesion → often benign or slow-growing
21
Q
What does an ill-defined margin suggest in a bone lesion?
A
Rapid bone destruction with no reactive margin → suggests malignancy or infection
22
Q
What causes osteogenesis imperfecta?
A
Inherited mutations (AD or AR) affecting type I collagen (COL1A1/COL1A2 genes) resulting in impaired collagen maturation → fragile bones with predominantly woven bone (immature, disorganized)
23
Q
What are classic clinical signs of OI?
A
Fractures, blue sclera, hearing loss, misshapen blue-yellow teeth.
24
Q
What happens to teeth in Dentinogenesis Imperfecta (Type I – OI)?
A
abnormal dentine causing fragile, discolored teeth with bulbous crowns, small pulp, and enamel shearing
25
What causes osteopetrosis?
Defective osteoclast function → impaired bone resorption and bone formation continues, but no remodeling occurs → dense but brittle bone (mostly woven)
26
What are complications of osteopetrosis?
- Narrow foramina → nerve compression
- Decreased marrow space → pancytopenia, myelophthisic anemia
- Increased infection risk
27
What are the two forms of osteopetrosis?
- Autosomal Dominant (AD): Benign; diagnosed in adolescence or adulthood → fractures, cranial nerve compression, infections
- Autosomal Recessive (AR): Malignant; diagnosed in utero → more severe with early death
28
What is osteoporosis?
Loss of bone density and structure → fragile bones, especially in older women with increased risk of fracture
29
What are key risk groups for osteoporosis?
Elderly, postmenopausal women
* x-rays dont detect till 30-40% of bone mass is lost
30
How are rickets and osteomalacia similar and different?
both are vitamin D deficiencies or impaired metabolism leading to poor mineralization of osteoid → soft, deformed bones
- Rickets = children → deformities (e.g. bowed legs)
- Osteomalacia = adults → pain, fractures
31
What does Hyperparathyroidism do to bone and what are the two types?
↑ PTH → ↑ osteoclast activity → bone resorption and osteopenia
- Primary: Tumor
- Secondary: Renal disease (e.g. ESRD/dialysis)
32
what are the late complications of hyperparathyroidism?
- Osteitis Fibrosa Cystica: Bone cysts due to chronic resorption (rare today)
- Brown Tumors: Not true tumors – they are reactive masses of fibrous tissue from hemorrhage and repair
33
What is Paget Disease of Bone (Osteitis Deformans)?
A chronic disorder characterized by abnormal bone remodeling involving excessive bone resorption, followed by excessive bone formation resulting in structurally disorganized bone → woven bone with a mosaic or "jigsaw puzzle" appearance
34
What is the epidemiology of Paget Disease of Bone (Osteitis Deformans)?
- Occurs later in life, very rare before age 40
- More common in England, Western Europe, Australia, and New Zealand
- 85% are polyostotic (involving multiple bones), while 15% are monostotic
- Frequently affects the skull (25–65%), pelvis, spine, and long bones
35
What is a common complication of Paget Disease?
Risk of osteosarcoma (1–3%)
36
What are bone fractures and what are the 7 different types of fractures?
Loss of bone integrity due to mechanical injury or reduced bone strength
1. Simple: Clean break with no skin communication
2. Compound: Bone communicates with the skin surface (open fracture)
3. Comminuted: Bone is fragmented into multiple pieces
4. Displaced: Bone ends are not aligned
5. Stress Fracture: Small cracks due to repetitive force (e.g., running)
6. Greenstick: Incomplete fracture; more common in children due to flexible bones
7. Pathologic Fracture: Occurs in weakened bone (e.g., tumors, osteoporosis).
37
What are the four main stages of fracture healing?
1. Hematoma and Inflammation (1–7 days)
2. Soft Callus (2–3 weeks)
3. Hard Callus (2–4 months)
4. Remodeling (months to years)
38
What is osteonecrosis, and what causes it?
Ischemic death of bone due to loss of blood supply
- common causes: trauma, steroids, alcohol, sickle cell, radiation.
39
What are the main outcomes of osteonecrosis?
- Repair: Hyperemia, creeping substitution, and new bone formation
- Collapse: Particularly in weight-bearing bones, leading to arthritis
40
What is a bone infarct?
localized region of bone necrosis in the medullary cavity, with no nuclei in cells
41
What is osteomyelitis, and what are its common causes?
Infection of bone marrow and surrounding bone, often by Staphylococcus aureus.
- children: hematogenous spread
- adults: trauma or contiguous spread
- Sickle cell anemia patients → common cause is Salmonella
42
How is osteomyelitis diagnosed?
- Bone biopsy and blood cultures are gold standards for confirming infection
- Radiographs may show bone destruction and periosteal reaction
43
What are the primary symptoms of acute osteomyelitis and what percentage of cases transition to chronic?
Fever, malaise, elevated ESR, local pain, and swelling
- 5–25% may not resolve and become chronic
44
What are the radiographic findings in acute osteomyelitis?
Radiolucency (bone destruction) and sclerosis (reactive bone formation)
45
What is the primary cause of TB osteomyelitis and where does it mainly infect?
Mycobacterium tuberculosis, especially in immunocompromised patients
- occurs mainly in the spine (Pott's disease), long bones, and joints
46
What characterizes chronic osteomyelitis?
Persistent infection with necrotic bone and fistulous tracts lasting months to years
47
What are complications of chronic osteomyelitis?
Limb length discrepancies, joint extension, amyloidosis, and squamous cell carcinoma in draining tracts
48
What patient populations are most at risk for chronic osteomyelitis?
Adults aged 40–50 years, especially those with trauma, DM, or vascular disease
49
What are the two major classifications of joints?
- Solid (Non-Synovial): Fibrous and Cartilaginous.
- Cavitated (Synovial): Fluid-filled, freely movable
50
Where are the main types of Solid (Non-Synovial) Joints found?
- Fibrous Joints: cranial sutures, bonds between roots of teeth and jawbones
- Cartilaginous/Synchondrosis Joints: symphysis between the sternum and ribs, pelvic bones
51
Where are the anatomical components found in Cavitated (Synovial) Joints and what are their roles?
1. Synovial Lining:
- Type A Synoviocytes (phagocytic) → Clear debris
- Type B Synoviocytes (fibroblast-like) → produce hyaluronic acid and synovial fluid
2. No basement membrane → allows for easy exchange of nutrients
3. Synovial Fluid: provides lubrication and nutrition to the joint
4. Hyaline Cartilage: covers the articular surface, lacks blood vessels, lymphatics, and nerves but is composed of
- 70% water, hyaluronic acid, proteoglycans, and collagen type II
52
What is degenerative joint disease (osteoarthritis)?
Chronic cartilage breakdown and bone changes due to wear and tear or genetics
53
What are typical histological features of osteoarthritis?
Fibrillation, subchondral sclerosis, tide mark, osteophyte formation
54
Which joints are most commonly affected by osteoarthritis?
Weight-bearing joints: Knees, hips, spine, hands
55
What non-surgical management strategies are used for osteoarthritis?
exercise/stretching, massage, weight control may help, also NSAIDS, corticosteroid injections
56
What is Rheumatoid Arthritis?
Chronic autoimmune disease characterized by nonsuppurative, proliferative, inflammatory synovitis that leads to joint destruction and systemic complications
57
What immune components are involved in RA?
- T-helper cells → TNF, IL-1, IL-6, IFN
- Macrophages, plasma cells
- Rheumatoid Factor (RF) → IgM/IgA against IgG
58
What are the characteristic joint deformities in RA?
- Ulnar deviation
- Swan-neck deformity
- Boutonnière deformity
59
What are common clinical features of RA?
- symmetric arthritis affecting small joints: hands, feet, MCP and PIP joints
- Extra-articular manifestations: Blood vessels, lungs, heart, and skin involvement
- Rheumatoid Nodules: Subcutaneous lumps resembling necrotizing granulomas
60
What are the pathological features of RA?
- Synovial Hyperplasia: Thickening of the synovial membrane
- Pannus Formation: Abnormal granulation tissue that invades cartilage and bone
- Angiogenesis: Increased blood vessel formation within the synovium
- Inflammatory Infiltrates: Dense collections of lymphocytes, plasma cells, and macrophages
- Fibrous and Bony Ankylosis: Fusion of the joint in later stages
61
what are the radiographic findings for RA?
- Joint effusion
- Osteopenia (localized bone loss)
- Cartilage erosion
- Narrowing of joint space
62
What are the management strategies for RA?
Medications:
- Corticosteroids (CS) → Reduce inflammation
- TNF antagonists → Block tumor necrosis factor
- Methotrexate → Inhibits cell proliferation and immune activity
Surgical Intervention:
- Joint replacement or synovectomy in severe cases
63
What is Septic Arthritis?
Infectious arthritis caused by bacterial invasion of the joint space through hematogenous spread (bloodstream), contiguous spread from adjacent soft tissue infections, osteomyelitis, or direct inoculation from trauma or surgery that leads to rapid joint destruction if untreated
64
What are the main causative organisms for septic arthritis?
Adults:
- Staphylococcus aureus (most common)
- Streptococcus species
Children:
- Haemophilus influenzae
Special cases:
- Gonococcus → sexually active adults
- Borrelia burgdorferi → Lyme arthritis
- Mycobacterium tuberculosis → chronic septic arthritis
65
What is the major complication of untreated septic arthritis?
Ankylosis (joint fusion) and osteomyelitis
66
What is Gout?
A form of crystal-induced arthritis caused by the accumulation of monosodium urate (MSU) crystals in the joints which results in acute inflammation and intense pain mainly after years of hyperuricemia (high uric acid levels in the blood).
67
What is the typical shape and birefringence of Gout crystals and what joints are commonly affected?
Needle-shaped, negatively birefringent (yellow when parallel to polarizer) mainly affecting great toe (podagra), knees, ankles, wrists
68
What is Pseudogout, and what crystals are involved?
A crystal-induced arthritis caused by Calcium Pyrophosphate Dihydrate (CPPD) deposition
69
How do crystals of Pseudogout appear and what joints are commonly involved?
Rhomboid-shaped, positively birefringent (blue when parallel to polarizer) mainly affecting the knee, wrist, elbow and shoulder
70
What conditions is Pseudogout often associated with and what can it be confused for?
- Diabetes, hemochromatosis, hyperparathyroidism, aging
- OA, RA and Gout
71
What is Osteoid Osteoma?
Benign, small cortical tumor (<2 cm) occurring in the first three decades of life
- common in young males
- tibia and femur
- painful but responds to NSAIDs
- visible on X-ray as a nidus
72
What is Osteosarcoma?
Malignant tumor of bone with osteoid production by malignant cells
- peak age is 2nd and 3rd decades (teens and young adults)
- later peak in patients with pre-existing bone diseases (e.g., Paget's disease).
- common location includes metaphysis of long bones, especially around the knee (50%)
73
What are the genetic mutations commonly associated with Osteosarcoma?
- RB gene mutation: Increases risk 1000 times
- TP53 mutation: Associated with Li-Fraumeni Syndrome
- MDM2 and CDK4 overexpression in low-grade osteosarcoma
74
What is the treatment approach for Osteosarcoma?
Multimodal therapy: Neoadjuvant chemotherapy → Surgery → Chemotherapy
75
What is Osteochondroma, and what genetic mutations are involved?
Benign exostosis (bony projection with a cartilage cap) that is <2 cm considered mainly solitary (85%)
- hereditary is with mutations in EXT1 and EXT2 and hereditary multiple exostoses have increased risk of secondary chondrosarcoma
76
What is Chondroma (Enchondroma)?
Benign cartilage tumor associated with Ollier disease and Maffucci syndrome with a risk of secondary chondrosarcoma at about 20%
77
What is Chondrosarcoma and what is the grading system?
Malignant cartilage-producing tumor that often presents in the pelvis, shoulder, and ribs
Grading System:
- Grade 1: Well-differentiated, best prognosis
- Grade 2: Intermediate features
- Grade 3: Poorly differentiated, 70% metastasis (lungs), high cellularity
78
What is Secondary Chondrosarcoma?
A chondrosarcoma that arises on a benign
precursor
- Risk in a solitary/multiple osteochondroma is around 2%
- Risk in multiple enchondromas is 2-20%
79
What are fibromas, non-ossifying fibromas, and fibrous dysplasias?
Benign lesions, sometimes involving the maxilla and mandible and important in differential diagnosis on X-ray
80
What is Fibrous Dysplasias?
A benign bone disorder caused by a somatic gain-of-function mutation in the GNAS1 gene where normal bone is replaced with fibrous tissue and irregular woven bone that results in weak, deformed bones that are prone to fractures and deformities
81
What is Ewing's Sarcoma, and what is its characteristic genetic feature?
Highly aggressive small blue cell bone tumor in children and young adults characterized by t(11;22) translocation (EWS/FLI1 or EWS/ERG)
82
Which cancers are most likely to metastasize to bone?
- adults: breast, lung, prostate, and kidney cancers
- children: neuroblastoma, Wilms tumor, Rhabdomyosarcoma
83
What are the general characteristics of soft tissue tumors?
Sarcomas are 1% of all malignant tumors and classified as:
- Benign
- Intermediate → Locally aggressive, rarely metastasizes
- Malignant
84
What are the most common soft tissue Sarcomas?
- Liposarcoma (75%)
- Leiomysarcoma
- Synovial Sarcoma
- Nerve Sheath Tumors
85
What are Lipomatous Tumors?
- Lipoma (benign) → most common soft tissue tumor.
- Liposarcoma (malignant): most common in adults >50, 3 main types: Well-differentiated (MDM2, CDK4), Myxoid, Pleomorphic.
86
What are examples of Fibrous Tumors?
- Fibromas and benign fibromatoses
- Nodular fascitis –UE, young adults, h/o trauma
- Superficial fibromatosis: infiltrative. Palmar, planta
- Deep fibromatoses/desmoid-recur (do not metastasize)
- Fibrosarcoma
87
What are the two smooth muscle tumors?
- Leiomyoma: benign tumor, common in uterus and GI tract.
- Leiomyosarcoma: malignant tumor, 10-20% of all sarcomas common in uterus, retroperitoneum, GI and vessels
88
What are two skeletal muscle tumors?
- Rhabdomyoma (benign): common in adults, fetus and genitals
- Rhabdomyosarcoma: aggressive, embryonal and alveolar in children, pleomorphic in adults
89
What are three types of vascular tumors?
- Hemangioma (benign)
- Kaposi Sarcoma (intermediate)
- Angiosarcoma (malignant)
90
What are the features of Schwannoma as a Peripheral Nerve Tumor?
typically sporadic, slow-growing, rarely transforms into malignancy but can occur in neurofibromatosis Type 2 (NF2)
- Encapsulated and well-demarcated.
- Contains antoni A: dense cellular areas and antoni B: Loose, myxoid regions
91
What are the characteristics of Neuroma as a Peripheral Nerve Tumor?
Non-neoplastic, usually post-traumatic painful overgrowth of nerve fibers and Schwann cells
92
What are the characteristics of Neurofibroma as a Peripheral Nerve Tumor?
Can be sporadic or inherited, associated with Neurofibromatosis Type 1 (NF1) and has potential for malignant transformation → Malignant Peripheral Nerve Sheath Tumor (MPNST)
93
What is Plexiform Neurofibroma?
benign peripheral nerve sheath tumor that appears as a "bag of worms" with irregular nerve bundles and nodular appearance associated with NF1
