arthritis arthritis is diagnosed before the detection of ILD,

arthritis associated
pneumonitis also should be considered as a differential diagnosis. Rheumatoid arthritis is a systemic inflammatory
disorder mainly affecting the joints, and is associated with autoantibody
production.  Pulmonary involvement is a common extra articular
manifestation, while Interstitial lung disease (ILD) being the primary
pulmonary manifestation of RA13. The two main histopathological patterns of
ILD that are observed in those patients are  the nonspecific
interstitial pneumonia (NSIP) pattern and the usual interstitial pneumonia
(UIP) pattern , while organizing pneumonia,diffuse alveolar damage, lymphocytic
interstitial pneumonia and desquamative interstitial pneumonia are less common
patterns14.

Most of the time Rheumatoid arthritis is diagnosed before
the detection of ILD, but in some cases, respiratory
symptoms may precede articular symptoms.So it is essential to assess signs and
symptoms of connective tissue disease when evaluating a patient with pulmonary
disease of unknown etiology.

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Physical examination of patient with Rheumatoid arthritis
ILD   may reveal inspiratory crackles, and restrictive physiology in
spirometry making it indistinguishable from hypersensitivity pneumonitis.

Findings of HRCT favors Rheumatoid arthritis associated organizing
pneumonia which is supported by short history of symptoms in our patient. Histology
of organizing pneumonia would reveal characteristic buds of connective tissue
(Masson’s bodies) in respiratory bronchioles and in alveolar ducts.

The exact mechanism of lung involvement in ILD is yet
unclear and patients with rheumatoid arthritis typically found to have
circulating autoantibodies, the most common being rheumatoid factor and
anti-cyclic citrullinated peptide (CCP) which are thought to have been linked
to the development of ILD.Our patient had positive rheumatoid factor in the serum,
but her anti-cyclic citrullinated peptide (CCP) were negative.

To date, there have been no placebo-controlled
therapeutic trials done in RA associated ILD. No consensus therapeutic guidelines
have been established so far and corticosteroids are the mainstay of therapy
with or without a cytotoxic agent such as azathioprine, cyclophosphamide or mycophenolate
mofetil .Particularly cases of NSIP and Organizing pneumonia( OP) are steroid
sensitive which can be managed with aggressive corticosteroid therapy 16. Moreover,
OP pattern shows rapid treatment response to steroids with a good recovery.

 Possibility of organizing pneumonia due to
bacterial infection which improved with target antibiotic therapy should also
be considered in our patient, who revealed positive BAL culture. But RA -OP is
the primary consideration as her clinical improvement and lung physiology improvement
was achieved only with steroids. 

 

 

CONCLUSION

Hyprsensitivity pneumonitis is
a rare, but a very important diagnosis to be made early to prevent devastating
complications by avoiding exposure to the environmental substances and
early treatment with medicines such as corticosteroids that reduce
inflammation. . If the condition goes undiagnosed and
untreated the chronic inflammation can cause irreversible lung scarring which
leads to poor prognosis.

Hence clinicians should be aware of
its etiology, clinical presentations and should be considered as a deferential diagnosis.
Obtaining proper history is very important to identify the
inciting agent, mainly because the first and most effective treatment is
antigen avoidance and it gives a clue to the diagnosis as well.

As discussed previously, in some rheumatoid arthritis
cases, respiratory symptoms may precede articular
symptoms. Certain sub types of ILD carry excellent treatment response to
therapy and good prognosis. So it is essential to assess signs and symptoms of
connective tissue disease when evaluating a patient with pulmonary disease of
unknown etiology in relevant clinical settings.

 

In our case, it is
a challenge to distinguish HP from connective tissue-related interstitial lung
disease because there was significant exposure to pigeon excreta prior symptoms
appears without characteristic HRCT features of HP along with positive
rheumatoid factor. But with the strong exposure history, sub acute HP would
still be the most probable diagnosis in our patient which nicely responded to
steroid therapy.