Pulmonary toxicity in a patient with psoriasis receiving methotrexate therapy

Pulmonary fibrosis developed secondary to methotrexate use in a patient with psoriasis vulgaris

Methotrexate is the folic acid analogue drug that used in various dermatological disorders, especially in psoriasis. Cutaneous and systemic side effects can be seen during methotrexate treatment. A 58-year-old female patient presented with persistent cough last one month. The patients past medical history was remarkable for psoriasis, for which she was on follow up for the last 14 years and received systemic methotrexate (12.5 mg/week) within the last eight months. The patient was referred to pulmonology for persistent cough. Computed tomography (CT) of the chest revealed pleural thickenning on the left lung, interlobular septal thickenning on the right lung and frosted glass areas in both lungs. Methotrexate induced pulmonary toxicity was considered and lung biopsy and bronchoscopy was performed to patient. The patient was diagnosed with methotrexate induced pulmonary toxicity based on the clinical, radiological and histopathological findings. Methotrexate treatment was stopped and a therapy with systemic corticosteroid 32 mg/day was initiated. Significant improvement was observed clinically and radiologically after one month of therapy. Methotrexate is a toxic drug to the lungs, but this condition is not common. All patients prescribed MTX should be advised for lung toxicity and to report the development of respiratory symptoms to their physician.

Methotrexate-induced pulmonary toxicity

Methotrexate is a widely used medication with an array of recognized side effects. The present report describes a case of methotrexate-induced pneumonitis in a patient with psoriasis, and demonstrates the hallmark clinical and investigational findings that support this infrequently encountered diagnosis. The ensuing discussion reviews the pathogenesis, management and prevention of this adverse drug reaction.

Lung

The lungs are particularly sensitive to RT, and are often the primary dose-limiting structure during thoracic therapy.

The alveolar/capillary units and pneumocytes within the alveoli appear to be particularly sensitive to RT.

Hypoxia may be important in the underlying physiology of RT-associated lung injury.

The cytokine transforming growth factor-beta (TGF-β), plays an important role in the development of RT-induced fibrosis.

The histopathological changes observed in the lung after RT are broadly characterized as diffuse alveolar damage.

The interaction between pre-treatment PFTs and the risk of symptomatic lung injury is complex. Similarly, the link between changes in PFTs and the development of symptoms is uncertain.

The incidence of symptomatic lung injury increases with increase in most dosimetric parameters. The mean lung dose (MLD) and V20 have been the most-often considered parameters. MLD might be a preferable metric since it considers the entire 3D dose distribution.

Radiation to the lower lobes appears to be more often associated with clinical symptoms than is radiation to the upper lobes. This might be related to incidental cardiac irradiation. In pre-clinical models, there appears to be a complex interaction between lung and heart irradiation.

TGF-β has been suggested in several studies to predict for RT-induced lung injury, but the data are still somewhat inconsistent.

Oral prednisone (Salinas and Winterbauer 1995), typically 40–60 mg daily for 1–2 weeks with a slow taper, is usually effective in treating pneumonitis. There are no widely accepted treatments for fibrosis.

A number of chemotherapeutic agents have been suggested to be associated with a range of pulmonary toxicities.

Generalized pustular psoriasis complicated by acute respiratory distress syndrome

Psoriasis has a chronic and relatively benign course. However, severe complications are possible. One rare complication is acute interstitial pneumonitis. This entity should be suspected when a patient presents with dyspnoea and high fever. Knowledge of this pathology is crucial, for although it is essential to rule out aetiologies requiring specific management such as microbial infection or drug-related syndromes, diagnosis should not be delayed as its severe clinical course is improved by corticosteroids. We report two patients with an acute respiratory distress syndrome arising during the course of pustular psoriasis. Repeated bacteriological testing in lungs and blood remained negative. In both cases lung involvement was severe, requiring artificial ventilation. Dramatic clinical resolution was obtained by using corticosteroids. Besides infectious causes and drug hypersensitivity to methotrexate or acitretin, acute respiratory distress syndrome, sometimes due to a pulmonary capillary leak syndrome, is a rare cause of pneumonitis in the course of psoriasis, and may be fatal. Its pathogenesis is unknown. However, animal models suggest a role for T-helper (Th) 1 lymphocytes, known to be activated in psoriasis, and a role for tumour necrosis factor-alpha, a major Th1 cytokine, in alveolar damage.

Pneumonitis complicating methotrexate therapy for pustular psoriasis

We report a patient with pustular psoriasis who developed interstitial pneumonitis after receiving weekly methotrexate (MTX) therapy at an average dose of 20 mg for 26 years. The patient responded dramatically to withdrawal of the drug and administration of corticosteroids. Pulmonary toxicity is a rare adverse effect of MTX therapy and is particularly uncommon in psoriatics. As interstitial pneumonitis is a potentially fatal but reversible complication, early respiratory symptoms even in patients on low-dose MTX treatment should be appropriately investigated.