25 - Bones, Joints, and Soft tissues Flashcards
Most common skeletal dysplasia; characterized by disproportionate shortening of the proximal extremities, bowing of the legs, and a lordotic (sway-backed) posture; pathology is mutations on FGFR3; autosomal dominant.
Achondroplasia
Most common lethal form of dwarfism; also caused by mutations in FGF3; usual cause of death is respiratory insufficiency (underveloped chest cavity).
Thanatophoric dysplasia
This is a group of hereditary disorders caused by defective synthesis of type I collagen; classic finding of a “blue sclerae” is seen in one type of this disorder; has 4 types; Type II is the most lethal; most commonly autosomal dominant.
Osteogenesis imperfect (OI) Brittle bone disease
- A disease that manifests with dense but structurally unsound bone due to mutations that result to impaired osteoclast function; also the first disease to be treated with HSC transplantation.
- Eponym for this disease:
- Osteopetrosis (Marble bone disease)
- Albers-Schonberg disease
The hallmark of this disease is loss of bone; cortices are thinned and trabeculae are reduced in thickness; osteoclastic activity is present but not dramatically increased; mineral content of the bone tissue is normal.
Osteoporosis
Basic difference between osteopenia and osteoporosis.
Severe osteopenia enough to increase risk of fractures in osteoporosis
Characterized by repetitive episodes of frenzied, regional osteoclastic activity and bone resorption, followed by exuberant bone formation, and finally by an apparent exhaustion of cellular activity; pathognomonic feature is a “mosaic pattern” of lamellar bone; associated with secondary osteosarcoma.
Paget disease of bone (Osteitis deformans)
Condition that results from Vitamin D deficiency; characterized by undermineralization of bone (as opposed to osteoporosis where bone mineral content is normal), rendering one susceptible to fractures.
Rickets (children)/Osteomalacia (adults)
Basic difference between rickets and osteomalacia, and osteoporosis.
Osteoporosis: normal mineralization, decreased bone mass; Rickets/Osteomalacia: decreased mineral content of bone
Components of von Recklinghausen disease of bone.
- Increased bone cell activity
- peritrabecular fibrosis
- cystic brown tumors
Term used for skeletal changes in chronic renal failure (including dialysis).
Renal osteodystrophy
Most common route of infection of pyogenic osteomyelitis.
Hematogenous dissemination
Most common organism implicated in pyogenic osteomyelitis overall.
S. aureus
Common organisms implicated in pyogenic osteomyelitis in IV drug users and patients with GUT infections.
E. coli, Pseudomonas, Klebsiella
Common organisms implicated in pyogenic osteomyelitis in neonates.
H. influenzae and GBS (organisms involves in sepsis)
Organism implicated in osteomyelitis in patients with sickle cell anemia.
Salmonella
A clinically serious form of tuberculous osteomyelitis involving vertebral bodies; can cause vertebral deformity, collapse and posterior displacement leading to neurologic deficits.
Pott disease
Bone-forming tumors with marked reactive bone (nidus) formation; clinically, <2 cm lesions; painful but relieved by NSAIDs.
Osteoid osteoma
> 2 cm, and pain is not relieved by NSAIDs; morphologically, less nidus formation
Osteoblastomas
Basic difference between osteoid osteoma/osteoblastoma and fibrous dysplasia.
Presence of osteoblastic rimming in osteoid osteoma/osteoblastoma
A bone-producing malignant mesenchymal tumor, characterized as gritty, gray-white tumors, often exhibiting hemorrhage and cystic degeneration; the production of mineralized or unmineralized bone (osteoid) by malignant cells is essential for diagnosis; associated with Codman triangle and sunburst pattern, radiographically; metaphyseal.
Osteosarcoma
Most common benign bone tumor, characterized by hyaline cartilage-capped outgrowths attached by a bony stalk to the underlying skeleton; metaphyseal.
Osteochondroma
Second most common malignant matrix-producing tumor of bone; a malignant tumor of chrondrocytes; these lesion arises within the medullary cavity of the bone to form an expansile glistening mass that often erodes the cortex; they exhibit malignant hyaline and myxoid cartilage; in its conventional form, it is almost always never found in children.
Chondrosarcoma
(Note: If you see malignant tumor made of chrondrocytes in a child, think chondroblastic osteosarcoma first)
Second most common group of bone sarcomas in children; primary malignant small round-cell tumor of bone and soft tissue, characterized by sheets of small round cells with scant, cleared cytoplasm, circled about a central fibrillary space or “Homer-Wright rosettes”; basically a PNET of bone; associated with a chromosomal translocation abnormality (t(11:22)).
Ewing sarcoma
A relatively uncommon benign tumor usually arising in individuals in their 20s to 40s; these are large and red-brown lesions with frequent cystic degeneration, composed of uniform oval mononuclear cells with frequent mitoses, with scattered osteoclast-type giant cells containing 100 or more nuclei; locally invasive; epiphyseal.
Giant cell tumor of bone (Osteoclastoma)
Most common skeletal malignancy.
Metastases
Most common form of arthritis; most fundamental feature is degeneration of articular cartilage; characterized by fibrillation and cracking of the articular cartilage matrix, bone eburnation, and bony outgrowths/spurs (osteophytes); full-thickness portions of the cartilage are lost, and the subchondral bone plate is exposed.
Osteoarthritis
Chronic inflammatory autoimmune disease principally attacking the joints; mechanism of disease is Type IV hypersensitivity; radiographic hallmark of this joint disease are joint effusions and juxta-articular osteopenia with erosion and narrowing of joint space and loss of articular cartilage.
Rheumatoid arthritis (RA)
Basic difference between OA and RA.
Joint fusion is absent in OA
Classic lesion of RA composed of proliferating synovial lining cells admixed with inflammatory cells, granulation tissue, and fibrous connective tissue; the overgrowth of this tissue is so exuberant that the usually thin, smooth synovial membrane is transformed into lush, edematous, frondlike (villous) projections.
Pannus
Examples of seronegative spondyloarthropathies.
Ankylosing spondylitis (Rheumatoid spondylitis, Marie-Strumpell disease), Reactive arthritis (Reiter syndrome), Enteritis-associated arthritis, Psoriatic arthritis
Crystal-induced arthropathy due to excessive amounts of uric acid; histologically characterized by a dense neutrophilic infiltrate permeating the synovium and synovial fluid; long, slender, needle-shaped monosodium urate crystals are frequently found in the cytoplasm of the neutrophils as well as in small clusters in the synovium.
Gout
Pathognomonic feature of gout; formed by large aggregations of urate crystals surrounded by an intense inflammatory reaction of lymphocytes, macrophages, and foreign-body giant cells, attempting to engulf the masses of crystals.
Tophi
Crystal-induced arthropathy due to calcium pyrophosphate deposition; crystals are rhomboid, and positively-birefringent.
Pseudogout
Most common soft tissue tumor of adulthood.
Lipoma
Most common sarcoma of adulthood.
Liposarcoma
Most common soft tissue sarcoma of childhood and adolescence.
Rhabdomyosarcoma
Immunostain for rhabdomyoblastic differentiation.
Myogenin
Most common neoplasm in women: common site is the uterus.
Leiomyoma
Immunostains for smooth muscle differentiation.
Smooth muscle actin, desmin
