Methotrexate-affected lungs in the case of rheumatoid arthritis

Clinical History

A 70-year-old male patient demonstrated a normal white blood count (normal values for both neutrophils and eosinophils), and his chest X-ray photographs showed a bibasal interstitial reticulonodular shadowing.

Imaging Findings

The investigations done on a 70-year-old male patient demonstrated a normal white blood count (normal values for both neutrophils and eosinophils), and his chest X-ray photographs showed a bibasal interstitial reticulonodular shadowing. The results of HRCT confirmed the occurrence of diffuse bilateral fibrotic changes with architectural distortion, traction bronchiectasis, and honeycombing. There were also some areas of discrete ground glass opacification.

Discussion

The 70-year-old male patient was managed conservatively with oxygen therapy and withdrawal of methotrexate. Over the next 2–3 weeks, the patient showed a dramatic clinical improvement, with normalisation of his breathing, exercising capacity, and oxygen saturations. The difficulty in this case was to establish the cause of the patient's deterioration. The differential diagnosis included a pulmonary manifestation of his rheumatoid condition, which is a complication that occurred during his drug therapy. Pulmonary manifestations of rheumatoid lungs include: (1) Diffuse interstitial pulmonary fibrosis mostly of UIP type and present in 10% of patients, is clinically, radiographically, and histologically similar to ideopathic pulmonary fibrosis. HRCT classically shows a bibasal subpleural honeycombing, with traction bronchiectasis. The results of pulmonary function tests show restricted lung volumes and gas transfer typical of pulmonary fibrosis. (2) more common are airway abnormalities, in up to 70% especially in patients who have no ILD such as chronic bronchitis, bronchiactasis and obliterative bronchiolitis (3) Pleural disease(in up to 40%) with pleurisy or pleural effusion. The pleural fluid is characteristically an exudate (protein >30 gl), with a raised LDH, a low complement and a high titre of rheumatoid factor. (4) Pulmonary nodules and Caplan’s syndrome. Pulmonary nodules may be discovered incidentally, and they may cavitate, become infected, cause haemoptysis, or rupture into the pleural space producing a pneumothorax. Caplan’s syndrome occurs where coal worker's pneumoconiosis or other pneumoconiosis becomes complicated by rheumatoid nodules. (5) Obliterative bronchiolitis typified by progressive narrowing and gas trapping of small airways. (6) Organising pneumonia with patchy consolidation. (6) Pulmonary vasculitis and haemorrhage. Methotrexate characteristically induces an acute reversible cellular interstitial pneumonitis. It may induce lung disease irrespective of the indication for which it is prescribed. The associated immunosuppression also increases the risk of infections, which include conditions such as pneumocystis carinii pneumonia. PCP was excluded in that patient on basis of clinical and diagnostic back ground wiht following clinical improvement in responce to measuers taken at time. Drug induced lung disease induced by methotrexate is seen in 5-10% of cases.Morphological findings include ground glass appearance in most cases as seen in this case, less often features of OP or DAD. The fact of drug induced lung diseas was based on exclusion of overlying infection, morphlogical HRCT findings during acute symptoms and clinical improvement of patient after cessation of the medication. NO follow up imaging was performed for that patient.

Differential Diagnosis List

Final Diagnosis

Methotrexate induced pneumonitis in rheumatoid lungs.

URL:	https://www.eurorad.org/case/3397
DOI:	10.1594/EURORAD/CASE.3397
ISSN:	1563-4086