Discussion
RA is usually diagnosed based on the classification of the American
college of rheumatology (5). According to
the classification, A score of more or six is usually indicating RA, the
classification includes features like Involved joint type, duration and
serology markers such as CRP, ESR, RF and anti-CCP. When the patient
still exhibit symptoms and signs of RA but his serological markers are
negative this is an indication of seronegative rheumatoid arthritis. RA
has long been recognized as an extremely heterogeneous disorder of
immune dys-regulation. Despite an ever-growing appreciation of the role
of circulating autoantibodies in the progress of ’seropositive’ disease,
the pathogenesis of sero-negative RA remains poorly understood
(1).
The clinical presentation and scenario of this case can fit with many
diagnoses such as undifferentiated arthritis which is an overlap
syndrome with RA and not fit well known clinical disease categories (
e.g reactive arthritis and sero-negative RA)
(8, 9).
Although, synovial knee biopsy confirmed the diagnosis. other possible
diagnosis overlaps with this patient condition include reactive
arthritis, but the absence of infection exclude the diagnosis as the
swelling and joint pain in reactive arthritis mainly triggered by
infection (10). Psoriatic arthritis
includes similar clinical features such as joints pain and stiffness and
the diagnosis is primarily based on the clinical phenotype due to the
diversity of the associated features which include nail and skin
disease, uveitis, dactylitis and osteitis
(11). And these skin manifestations were
not presented in this case.
The synovial biopsy is not usually used for routine diagnostic or
therapeutic purpose in RA patients (12).
However, synovial tissue examination can assist in the diagnosis of some
joint infection. Although there is no diagnostic role in acute RA,
although, synovial tissue analysis that can provide significant
prognostic information, recent studies have shown that examined
mediators of joint damage and synovial tissue inflammation were found to
be linked with unfavourable radiological and clinical outcomes
(13).
Although genetic variation has long been supposed to account for around
60% of RA risk (14), however recent
reports indicates that this figure for heritability may be significantly
lower in sero-negative RA (15). It
follows that environmental factors such as smoking should play a more
essential role in seronegative RA, but much has yet to be understood in
this area (16,
17).