PATH Lab Exam 1 Flashcards
Where do osteocytes come from?
Once an osteoblast becomes surrounded by matrix, it becomes an osteocyte.
From what cell is the osteoclast derived?
It is derived from a monocyte precursor cell located in the hematopoietic marrow.
Why are vertebrae preferentially affected in osteoporosis?
Loss of bone is most rapid from trabecular bone. Vertebrae have a prominent trabecular component.
How does estrogen serve to maintain bone mass?
Estrogen may maintain bone mass by inhibiting the release of cytokines that stimulate bone resorption (IL-1, TNF) while upregulating the synthesis of other cytokines (TGF-beta) involved in bone formation.
response of bone to fracture
Osteoblasts arise from pluripotent progenitor cells in the periosteum and granulation tissue. They produce woven bone, resulting in a bony callus that stabilizes the fracture site.
What is the significance of the empty lacunae at the ends of the trabecular bone?
The empty lacunae indicate that the bone is necrotic.
Which organ is the preferential site for metastases in patients with osteosarcoma?
The lungs.
production of osteoid matrix by the tumor cells
osteosarcomas
multiple cells can be found within a single lacuna
Chondrosarcoma
At what age do patients develop chondrosarcoma, and which anatomic sites in the skeleton are affected?
Patients with chondrosarcoma are older than those with primary osteosarcoma; the mean age for chondrosarcoma is 43 years. The most frequent locations are in the pelvis, proximal femur, ribs, sternum, and the shoulder girdle. It is the most common malignant tumor of the scapula and sternum.
What are the most common age and sex of a patient with giant cell tumor of bone?
Giant cell tumors usually arise between the age 25-45, and there is a slight female predominance.
Prostatic adenocarcinoma produces __________ foci in the skeleton.
osteoblastic
How does the distribution of affected joints in the RA hand differ from that seen in degenerative joint disease?
The lesions of degenerative joint disease in the hand are found in the distal interphalangeal joints, are bony, and are not symmetrical.
How are joints destroyed in RA?
- In RA, there is diffuse narrowing of the joint space.
- The cartilage is destroyed by the release of IL-1 and TNF, which depresses the synthesis of proteoglycans, and by proteases released from neutrophils.
- As well, proliferation of the synovial membrane leads to pannus formation, which isolates the cartilage from the synovial fluid, its source of nutrients. The severe, extensive damage of RA often leads to ankylosis.
- In chronic RA, the periarticular bone is osteoporotic, a change secondary to disuse of the affected limbs, to the stimulation of osteoclasts by corticosteroid therapy, or to the release of RANK-L by activated lymphocytes in the synovium.
Which class of lymphocytes predominates in the inflammatory infiltrate in RA?
- T cells play the pivotal role accounts for the inflammation and joint destruction.
- CD4+ cells accumulate in affected joints, where they stimulate monocyte-macrophages to release cytokines and recruit B cells, which produce the autoantibody rheumatoid factor.
- During active inflammation, the synovial tissue generates a plethora of cytokines/growth factors. It is now generally accepted that IL-1 and TNF are key mediators in the cytokine cascade.
List two important histologic changes found in the synovial membrane in joints affected by rheumatoid arthritis.
The synovium is proliferative and is infiltrated by numerous lymphocytes and plasma cells.
What is the pannus?
The pannus consists of the inflamed, hyperplastic synovium that extends over the articular surface.
How does RANK-L contribute to the destruction of the joint?
RANK-L is released from activated lymphocytes in the synovium, stimulating the proliferation of osteoclasts. Osteoclasts rapidly erode the subchondral bone.
Where do rheumatoid nodules typically develop?
The nodules typically appear on the extensor surface of the forearm below the elbow, or at sites of local pressure, such as the Achilles tendon. Less commonly, they form in the lungs, spleen, myocardium, and heart valves. The subcutaneous nodules are firm, nontender, and round to oval.
What is the common name of osteophytes that develop at the distal interphalangeal joints of women?
These osteophytes are called Heberden nodes.
What would be the characteristic feature of joint fluid aspirated from the joint affected with gout?
The fluid would contain large numbers of neutrophils and long, needle-like, sodium urate crystals.
Besides joints, what other organ is affected in gout?
In patients with chronic gout, the kidney can be severely damaged; approximately 20% of patients die of renal failure. Renal lesions are many: precipitation of urates in the medulla forms tophi; uric acid stones may form; and in some cases, there is acute renal failure due to precipitation of urates in the collecting tubes.
Which nonmelanocytic disorders of the skin can present as pigmented lesions?
Seborrheic keratoses are very common pigmented lesions, occuring most frequently in middle-aged and older individuals. Basal cell carcinomas usually present as a pearly papule or nodule with dilated blood vessels (telangiectasias), but they can also occur as an ulcerated, an eczematous, or a pigmented lesion. Vascular tumors (hemangioma, Kaposi sarcoma) often have a blue-brownish color.
