RA

Prep for USMLE Forum

» Log in | Register

Forum

Step 1

Match

Prep4USMLE Forum » USMLE Step 1 Forum » Pathology Forum

Author

11 Posts

Idiopathic
Forum Guru

Topics: 19
Posts: 641

04/05/04 - 03:10 PM

A 48-year old female presents to her doctor with painful and swollen PIP and MCP joints on the 2nd and 3rd fingers of both hands. The physician recognizes this as an inflammatory condition, and does an antibody screen of the joint fluid, as well as a culture. What are the most likely findings?

A: IgG antibodies against the articular cartilage.
B: IgG antibodies against the periosteum.
C: IgG antibodies against hyaluronic acid.
D: IgM antibodies against hyaluronic acid.
E: IgG antibodies against the Fc portion of IgM.
F: IgM antibodies against the Fc portion of IgG.
G: IgG antibodies against the synovial lining cells.
H: Gram negative diplococi.

usmleasr
Forum Guru

Topics: 105
Posts: 970

04/05/04 - 03:14 PM

F. :roll:

Idiopathic
Forum Guru

Topics: 19
Posts: 641

04/05/04 - 03:44 PM

Didnt like it, eh?

asmi
Forum Hero

Topics: 1043
Posts: 4,609

04/05/04 - 05:34 PM

can u name the disease ?

Idiopathic
Forum Guru

Topics: 19
Posts: 641

04/05/04 - 06:24 PM

Its RA - Rheumatoid arthritis. The antibody found is IgM directed against the Fc portion of circulating IgG antibies. The HLA association is Dr4 and the most common joint complication in the hand is inflammatory change at the MCP and PIP (no DIP involvement) of the 2nd and 3rd digits bilaterally.

Quinn
Forum Elite

Topics: 63
Posts: 308

04/05/04 - 08:22 PM

Idiopathic great explaination....good job guys. When are you guys online I would not mind participating....if you don't mind, or at least seeing the questions with you.

___________________
The universe will yield to the will of the determined person.

Idiopathic
Forum Guru

Topics: 19
Posts: 641

04/05/04 - 08:25 PM

I made this one up based on class discussion today grin

mdwannabe
Forum Guru

Topics: 37
Posts: 1,133

04/05/04 - 08:35 PM

Ok... IgM is the rheumatoid factor, thats a given! But don't you think that IgG should first react to own tissue before IgM will start attacking the Fc portion of IgG???

___________________
"Life not lived for others, is not worth living" Uncle Einstein
"A life is not important, except in the impact it has on other lives" -Jackie Robinson

mdwannabe
Forum Guru

Topics: 37
Posts: 1,133

04/05/04 - 08:40 PM

Besides RF is nor specific for RA, it apperars in a bucnh of other autoimmune conditions, and in 5% of normal. The point is do not go by lab result, go by overall presentation.

___________________
"Life not lived for others, is not worth living" Uncle Einstein
"A life is not important, except in the impact it has on other lives" -Jackie Robinson

Idiopathic
Forum Guru

Topics: 19
Posts: 641

04/05/04 - 09:13 PM

#10

"mdwannabe" wrote:
Ok... IgM is the rheumatoid factor, thats a given! But don't you think that IgG should first react to own tissue before IgM will start attacking the Fc portion of IgG???

Thats just the point, IgG doesnt attack the tissue. The insult (viral?) causes the autoimmune reaction, which involves (more times than not) the IgM antibody that gets directed against the Fc portion of IgG. Just as simple as that. The tissue damage is due to neutrophilic invasion from complement activation of the IgM-IgG immune complexes.

asmi
Forum Hero

Topics: 1043
Posts: 4,609

04/05/04 - 09:37 PM

#11

good job idiopathic smiling face

You don't have permission to post.