Desquamative Inflammatory Pneumonia Caused by Marijuana

Abstract

INTRODUCTION: Desquamative interstitial pneumonia (DIP) is one of the rarest of the idiopathic interstitial pneumonias [1]. Most cases are caused by cigarette smoking, but drugs and other inhaled agents, including marijuana smoke, can also produce the same disease. The prognosis of patient with DIP is typically good, with mortality of patient ranging between 6-30%[3]. Treatment response is generally good with adequate responses to steroids and cessation of smoking. CASE PRESENTATION: 19 year old gentleman with a past medical history of Crohn's disease on Adalimumab, presented with cough 3 days after initiation of treatment. He admitted to smoking marijuana the day before his third dose. Soon after, he developed a dry cough and shortness of breath. He did not have any crackles on exam. He presented to the emergency room, where he was started on antibiotics for question of community-acquired pneumonia. Due to his persistence of symptoms he underwent a high resolution non-contrast CT scan of the chest that showed diffuse bilateral interstitial ground glass opacities, with some areas of confluent opacities in the right upper lobe, raising the concern for an interstitial lung disease. During his stay he was also noted to be hypoxic. He subsequently underwent a bronchoscopy that revealed an irritated and inflamed airway and bronchoalveolar lavage was prominent for lymphocytosis. An open lung biopsy showed alveolar macrophages in the airspaces and changes consistent with DIP. He was started on prednisone, which improved his symptoms and was successfully weaned off of oxygen. He is currently doing better with no evidence of residual interstitial disease, and has stopped smoking entirely. DISCUSSION: This case yet highlights the rarity of DIP as being caused by marijuana smoking, and the resolution of this disease with the cessation of smoking. Additionally confounding to this case is the fact that this could have also been caused by the drug Adalimumab, although unlikely given the fact that the sypmtoms started after smoking the marijuana. There have been case reports indicating that adalimumab can cause an interstitial type pneumonia that is responsive to steroids. CONCLUSIONS: The presentation of DIP in a patient who was on immunotherapy and is a marijuana smoker, should be taken into consideration as both these entities can cause this disease.