POPCORN LUNG

Introduction

Bronchiolitis obliterans is a type of obstructive lung disease affecting the small airways. It is a rare condition characterized by fibrosis of terminal and respiratory bronchioles; and spirometry showing predominant small airway dysfunction. It usually leads to progressive decline in lung function and has variable outcomes. Etiology includes lung transplant and hematopoietic stem cell transplantation, exposure to inhaled toxins and gases including mustard gas, nitrogen oxides, diacetyl and fiberglass. Bronchiolitis obliterans is also associated with autoimmune disorders. This is a case report of bronchiolitis obliterans in a coffee processing unit worker in Wayanad district of Kerala.

Case report

 A 51-year-old male patient, doing manual work, presented with a history of progressive breathlessness for the last 10 years. He also had cough with scanty expectoration. No history of haemoptysis or chest pain. He had few hospital admissions during the past 10 years mostly with febrile illness. He was being treated as chronic obstructive pulmonary disease. There was no history of childhood asthma or family history of asthma. He was a smoker for 25 years and stopped 5 years back. During this admission, X–ray chest was taken which showed hyperinflation and diffuse reticular shadows both sides with coalescence of shadows on both lower zones (Fig-1A). These lesions appeared different from the increased broncho-vascular markings that are usually seen in chronic bronchitis. Spirometry showed obstructive lung function with predominant small airway dysfunction (21% predicted).

High resolution computed tomography (HRCT) thorax revealed diffuse reticular shadows, few nodular shadows, thin walled cysts and air trapping. This type of HRCT appearance is seen in Popcorn lung and Marijuana smoking. He denied use of Marijuana at any point of time. He was working in a coffee processing unit for 20 years and quit the job once he developed respiratory symptoms. Coffee processing unit was a medium sized facility where coffee roasting and grinding were done. He used to work in both sections. Confirmation of diagnosis with a lung biopsy was suggested, but the patient did not favor any invasive procedure.

Fig: X-Ray Chest PA view showing hyperinflation and bilateral diffuse reticular shadows. HRCT Thorax axial section from the lower lobes shows extensive reticulation, bronchiolar wall thickening, air trapping and cyst formation. 

Discussion

The clinical and radiological presentation resembled that of “Popcorn Lung” reported in workers of a microwave popcorn plant in Missouri in 2002. This was caused by a flavoring agent termed diacetyl (2,3-butanedione) which is used to give the popcorn a buttery taste. Later, it was reported that this flavoring agent is extensively used in e-cigarettes, favoring the development of this condition among those who use e-cigarettes. Further, it is proved that this chemical is a natural byproduct in coffee-roasting and coffee-grinding processes. Hence, unacceptable levels of diacetyl in these units may cause popcorn lung. In their report, the Centers for Disease Control and Prevention (CDC) confirmed that occupational exposure to diacetyl and a related compound, 2,3-pentanedione, can cause bronchiolitis obliterans and loss of lung function. The CDC also reported that these potentially harmful chemicals were found at higher-than-expected levels at some coffee-processing facilities. Popcorn lung (bronchiolitis obliterans) often is associated with symptoms of cough and shortness of breath, similar to that seen in patients with COPD and asthma. This pathology is irreversible and progressive, and there is no definite treatment. Diagnosis is often delayed due to nonspecific clinical features and is initially treated as COPD or asthma. Lung tissue biopsy is necessary to confirm the diagnosis of bronchiolitis obliterans.

Wayanad district in Kerala is predominantly a tea and coffee growing farmland at a moderate high altitude. Hence there is lots of small and large scale coffee processing units. It is highly possible that workers in these processing units (Roasting or grinding) may be exposed to diacetyl leading to development of bronchiolitis obliterans. These patients due to their nonspecific symptoms and poor awareness of this entity are treated as COPD.