1. Pathology for year 2, unit 3
Lecture number 12.
NB: The total number of lectures is 17.

2. Pathological changes of joints
أ.م.د.محمد شنين علي العبادي M. B. Ch. B. & F. I. C. P.(Hematopathology) الثلاثاء2015/3/31 الساعة التاسعة صباحا

3. Pathological changes of joints
Previously you studied the pathological changes of joints in osteoarthritis (OA) and rheumatoid arthritis (RA). Q. What are the main differences between these joint disorders regarding the age, sex, weight, sites (joints which are affected), and pathological changes?

4. Pathological changes of joints in joint disorders other than OA & RA
1. Seronegative arthropathies. 2. Gout 3. Pseudogout. 4.Infectious arthritis 5. Others.

5. Pathological changes of joints in joint disorders other than OA & RA
Seronegative arthritis Represents group of diseases that cause arthritis with absence or negative test for serum rheumatoid factor (i.e there is no specific antibody or RF). These diseases are different from rheumatoid arthritis in which the RF test in patient’s serum is positive i.e there is specific antibody (IgM attached to IgG).

6. Pathological changes of joints in joint disorders other than OA & RA
Gout
Gout is a disorder that is caused by tissue accumulation of large amounts of uric acid.
NB: Uric acid is the end product of purine metabolism. So that excessive cellular DNA breakdown will result in an increase in purine which in turns causes an increase in uric acid production.
Aetiology: 90% are unknown & only 10% are known

7. Pathogenesis and morphological (structural) changes in gout
Uric acid (urate) crystals are precipitated in different tissues of the body, especially joints due to overproduction of uric acid or due to lower renal excretion of uric acid or due to both of them.
Such precipitation of urate crystals causes acute arthritis of for example big toe affecting mainly the synovial membrane (synovitis) with phagocytosis of crystals by white cells and production of IL1 and TNF….Q. What is similar to it?

8. Pathogenesis and morphological (structural) changes in gout
3. Another urate crystal deposition in the same joint will lead to another synovitis & another acute arthritis…..with such repeated deposition within a period of time, there will be chronic synovitis (chronic arthritis) with pannus formation. These crystals are whitish in color and called tophi. So that the name chronic tophaceous arthritis i.e frequent (repeated) acute attacks of acute arthritis in gout = chronic tophaceous arthritis.

9. Pathogenesis and morphological (structural) changes in gout
4. Urate crystals can also precipitate in other tissues like skin and kidneys resulting in gouty nephropathy (group of renal complications like renal stones).
Q. Select one pathognomonic (characteristic) pathological sign of gout?
Tophi
Collections of events (Pannus)
Answer: a

10. Big toe swelling + reddness in gout

11. Big toe radiological changes like soft tissue swelling.

12. Pseudogout
Pseudogout is another crystal deposition disease of joints in which calcium pyrophosphate crystals are deposited in joints causing arthritis. The cause is generally unknown, but the incidence is increasing with increasing age. Q. What is similar to such disorder?

13. Infectious arthritis
Arthritis can be due to infection by certain microorganism. The microorganism is directly entering the joint because of joint injury or indirectly through blood (i.e the microorganism is carried through blood to the joint).

14. Thank you