arthritis associatedpneumonitis also should be considered as a differential diagnosis.
Rheumatoid arthritis is a systemic inflammatorydisorder mainly affecting the joints, and is associated with autoantibodyproduction. Pulmonary involvement is a common extra articularmanifestation, while Interstitial lung disease (ILD) being the primarypulmonary manifestation of RA13. The two main histopathological patterns ofILD that are observed in those patients are the nonspecificinterstitial pneumonia (NSIP) pattern and the usual interstitial pneumonia(UIP) pattern , while organizing pneumonia,diffuse alveolar damage, lymphocyticinterstitial pneumonia and desquamative interstitial pneumonia are less commonpatterns14.Most of the time Rheumatoid arthritis is diagnosed beforethe detection of ILD, but in some cases, respiratorysymptoms may precede articular symptoms.So it is essential to assess signs andsymptoms of connective tissue disease when evaluating a patient with pulmonarydisease of unknown etiology.Physical examination of patient with Rheumatoid arthritisILD may reveal inspiratory crackles, and restrictive physiology inspirometry making it indistinguishable from hypersensitivity pneumonitis.Findings of HRCT favors Rheumatoid arthritis associated organizingpneumonia which is supported by short history of symptoms in our patient. Histologyof 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 yetunclear and patients with rheumatoid arthritis typically found to havecirculating autoantibodies, the most common being rheumatoid factor andanti-cyclic citrullinated peptide (CCP) which are thought to have been linkedto 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-controlledtherapeutic trials done in RA associated ILD. No consensus therapeutic guidelineshave been established so far and corticosteroids are the mainstay of therapywith or without a cytotoxic agent such as azathioprine, cyclophosphamide or mycophenolatemofetil .Particularly cases of NSIP and Organizing pneumonia( OP) are steroidsensitive 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 tobacterial infection which improved with target antibiotic therapy should alsobe considered in our patient, who revealed positive BAL culture. But RA -OP isthe primary consideration as her clinical improvement and lung physiology improvementwas achieved only with steroids.
CONCLUSIONHyprsensitivity pneumonitis isa rare, but a very important diagnosis to be made early to prevent devastatingcomplications by avoiding exposure to the environmental substances andearly treatment with medicines such as corticosteroids that reduceinflammation. . If the condition goes undiagnosed anduntreated the chronic inflammation can cause irreversible lung scarring whichleads to poor prognosis.Hence clinicians should be aware ofits etiology, clinical presentations and should be considered as a deferential diagnosis.Obtaining proper history is very important to identify theinciting agent, mainly because the first and most effective treatment isantigen avoidance and it gives a clue to the diagnosis as well.As discussed previously, in some rheumatoid arthritiscases, respiratory symptoms may precede articularsymptoms. Certain sub types of ILD carry excellent treatment response totherapy and good prognosis.
So it is essential to assess signs and symptoms ofconnective tissue disease when evaluating a patient with pulmonary disease ofunknown etiology in relevant clinical settings. In our case, it isa challenge to distinguish HP from connective tissue-related interstitial lungdisease because there was significant exposure to pigeon excreta prior symptomsappears without characteristic HRCT features of HP along with positiverheumatoid factor. But with the strong exposure history, sub acute HP wouldstill be the most probable diagnosis in our patient which nicely responded tosteroid therapy.