• Researchers call for detailed screening/assessment in asymptomatic patients for advanced sub-clinical organ tissue function related pathology

Marijuana use is associated with a spectrum of lung diseases and therefore, detailed screening and assessment should be arranged even in asymptomatic patients as there can be advanced sub-clinical parenchymal (relating to or affecting the functional tissue of an organ) pathology, a local case study recommended.

These observations and recommendations were made in a case report on "Chronic cannabis abuse causing ‘marijuana lung’ - Young man’s agony" which was authored by S. Wickramasinghe and M. Ahmed (the duo are Senior Clinical Fellows in Respiratory Medicine at the Chorley and South Ribble Hospital in Chorley in the United Kingdom), and Y. Haider (Consultant Respiratory Physician at the same Hospital) and published in the Ceylon Medical Journal's 67th Volume's First Issue in May, 2022.

Cannabis, as noted in N.B. Chinnappa, K. Zalewska and D. Mckeon's "Cannabis lung causing debilitating emphysema (a lung condition that causes the shortness of breath as the air sacs in the lungs/alveoli are damaged): Are we on the verge of an epidemic", is the most widely used, illicit drug among adolescents and young adults. There are, Wickramasinghe et al. point out, adverse effects of cannabis use on the lungs of young adults in the third and fourth decades of their life.

Wickramasinghe et al. presented the youngest patient to demonstrate extensive lung damage due to 'marijuana lung', presenting in his teenage years.

Case report

An 18-year-old patient was referred following an incidental finding of an abnormal chest X-ray, performed following a road traffic accident. On further inquiry, it was found out that he was a chronic cannabis user for the last six years, in which he used six joints of cannabis per day. In addition, he was formerly a smoker, having smoked five to six cigarettes per day until three years ago. He denied a history of having a chronic cough or wheezing but later admitted to struggling with insidious onset, exertional dyspnoea (difficult or laboured breathing).

On examination, he was slim and tall. There was no clubbing (deformity of the finger or toe nails associated with a number of diseases, mostly of the heart and lungs), nicotine stains, cyanosis (a bluish purple hue to the skin which is most easily seen where the skin is thin, such as the lips, mouth, earlobes and fingernails, and indicates that there may be decreased oxygen attached to the red blood cells in the bloodstream) or peripheral stigmata (a visible sign or characteristic of a disease such as a mark or a spot on the skin) of chronic liver disease. He was noted to have a hyper-extensibility of wrist and small hand joints and hyper-elasticity of the skin. His trachea was central and there was reduced air entry with hyper-resonance (greater than normal resonance, often of a lower pitch, on percussion of the body, indicating that too much air is present within the lung tissue) in the bilateral upper zones.

His chest X-ray showed right upper zone bullae (large blisters on the skin that are filled with clear fluid or a fluid filled sac or lesion that appears when fluid is trapped under a thin layer of the skin) with hyper-expanded lung fields (a region of interest in which specific radiologic signs are searched by a chest radiographic computer aided diagnostic system) which was not evident on a chest X-ray done nine months earlier. This was followed by a high resolution computerised tomography (HRCT - a scan which combines a series of X-ray images taken from different angles around the body and uses computer processing to create cross sectional images of the bones, blood vessels and soft tissues inside the body) thorax (chest) which showed upper zone limited paraseptal (damages the tiny ducts that connect to the lung's fragile air sacs that help one breathe) emphysema with bilateral upper lobe bullae more prominent in the right lung. He was further investigated with alpha-one antitrypsin (a protein made mainly by the liver, which then moves it into the bloodstream, and which protects the lungs and other organs from the harmful effects of irritants and infections) levels which were within the normal range and his connective tissue screening was negative. Further evaluation with lung function showed the forced expiratory volume in the first second (FEV1 - the volume of air in litres that is exhaled in the first second during forced exhalation after maximal inspiration), forced vital capacity (FVC - the maximum amount of air one can forcibly exhale from the lungs after fully inhaling), and the ratio between the FEV1 and the FVC. A two dimensional echocardiography (a non-invasive investigation used to evaluate the functioning and assess the sections of the heart) revealed normal cardiac function.

Disease progression

Based on upper lobe predominant paraseptal emphysema with upper lobe predominant bullae and the absence of cystic (a sac like pocket of membranous tissue that contains fluid, air, or other substances) lesions and nodules, and his exposures, a diagnosis of 'marijuana lung' was made. He was given cessation advice but despite this, during follow up, he was noted to have progressive exertional breathlessness on exertion after eight months from the initial presentation. Repeat HRCT showed progression of the disease. Based on the lung functions, the size of the bullae and the progression of the disease, he was referred to cardiothoracic surgeons and a bullectomy (surgery to remove air pockets in the lungs) was planned.

"Cannabis use is associated with several complications including the development of bullous lesion, emphysema, pneumothorax (a collapsed lung which occurs when air leaks into the space between the lung and the chest wall and this air pushes on the outside of the lung and makes it collapse), tendency to pulmonary infections and the development of lung cancer. There are a number of case reports and series describing the associations and the effects, although evidence of direct linkage is sometimes limited," Wickramasinghe et al. elaborated. P.T. Reid, J. Macleod and J.R. Robertson's "Cannabis and the lung" has also shown that the type of cannabis, and the method of smoking, are decisive factors with regard to the adverse effects of this agent on the lung.

"There is emerging concern that regular cannabis smoking may lead to a rapid development of chronic obstructive pulmonary diseases, although there is still a dispute as to whether cannabis smoking contributes to the development of emphysema. This case is unique as he is the youngest patient reported with a marijuana lung so far, with severe changes that appear to be directly attributable to the effects of marijuana itself. He had limited exposure to tobacco and was limited to marijuana use for the last three years with progressive chest X-ray changes noted during the course of the last year," Wickramasinghe et al. explained.

Dysfunctional lungs

Marijuana lung, Wickramasinghe et al. add, is associated with a specific pattern of pulmonary function tests. D.P. Tashkin, B.J. Shapiro and I.M. Frank's "Acute pulmonary physiologic effects of smoked marijuana and oral Δ9-tetrahydrocannabinol in healthy young men" has shown that smoking marijuana containing substances produces acute bronchodilation (expansion of the bronchial {the larger air passages of the lungs, including those that lead from the trachea/windpipe to the lungs and those within the lungs} air passages) for a duration of up to two hours. Wickramasinghe et al. mention that this effect has already been identified in the past, especially in the 19th Century, during which time marijuana was used to treat asthma. "Chronic cannabis use has been associated with large airway dysfunction leading to airflow obstruction and hyperventilation. Because of this, cannabis use is associated with apical (apex or the tip of a pyramidal or rounded structure, such as the lung or the heart) predominant emphysema with large bullae formation which is called the 'marijuana lung'. These patients usually present with a pneumothorax, usually due to a bullous rupture," Wickramasinghe et al. further noted.

"A characteristic lung function pattern has been detected. There is an increase in the functional vital capacity, the total lung capacity, the residual volume with a relatively normal FEV1. This leads to a reduction in the FEV1/FVC ratio, mimicking an obstructive feature but volume assessment will aid the diagnosis," Wickramasinghe et al. concluded.

In this case report, Wickramasinghe et al. also cited M.K. Johnson, R.P. Smith, D. Morrison, G. Laszlo and R.J. White's "Large lung bullae in marijuana smokers" and R. Rawlins, K.M. Brown, C.S. Carr and C.R. Cameron's "Life threatening haemorrhage after anterior needle aspiration of pneumothoraces. A role for lateral needle aspiration in emergency decompression of spontaneous pneumothorax" as evidence, in support of their findings.