The clinical story began innocuously. After a hospital admission for severe community-acquired pneumonia, the man was referred to a London outpatient clinic for persistent shortness of breath on climbing stairs and unintentional weight loss. Follow-up chest radiographs arranged to confirm that his pneumonia had resolved revealed something unexpected: a persistent right-sided pleural effusion, an abnormal collection of fluid in the space surrounding the lung, accompanied by collapse of the underlying lung tissue. What might have been dismissed as a lingering complication of infection instead became the first clue to a far more serious process.

Computed tomography imaging escalated the concern. The scan demonstrated a moderate right-sided pleural effusion with circumferential nodular thickening of the pleura, the delicate membrane that envelops the lung, along with enlarged lymph nodes near the heart and in the right hilum. Fluorodeoxyglucose-positron emission tomography, a scanning technique that highlights metabolically active tissue, showed diffuse uptake across the pleura with moderate avidity, and identified an enlarged intercostal lymph node that was accessible for biopsy. Formal staging placed the tumour at T3N1M0, indicating locally advanced disease with regional lymph node involvement but no distant spread.

Fluid drawn from the chest under ultrasound guidance was a cloudy yellow exudate, with a protein level of 54 grams per litre, a fluid-to-serum protein ratio of 0.72, glucose of 3.8 millimoles per litre and lactate dehydrogenase of 490 units per litre. Cytology showed lymphocytosis but, crucially, no malignant cells. The diagnostic breakthrough came from the intercostal lymph node itself. Histopathology revealed morphology and an immunoprofile consistent with an epithelioid-type malignant mesothelioma with lymphovascular invasion, and adenocarcinoma markers were negative. The tumour cells expressed calretinin, WT-1 and D2-40 while testing negative for TTF-1, a marker profile that firmly pointed to mesothelioma rather than lung adenocarcinoma.

Immunohistochemistry demonstrated retained expression of BRCA-1 associated protein, known as BAP1, and germline testing for BAP1 tumour predisposition syndrome came back negative. This mattered because BAP1 loss is a hallmark of many mesotheliomas and because inherited mutations in BAP1 define a recognised cancer predisposition syndrome. Broader germline panel testing was not performed, however, leaving open the possibility of other inherited susceptibility genes. After discussion by the lung cancer multidisciplinary team and referral to the regional mesothelioma service, the tumour was deemed inoperable, and the patient began combination immunotherapy with nivolumab and ipilimumab, a checkpoint inhibitor regimen that has transformed outcomes for some patients with advanced disease.

The puzzle was the exposure history. The patient was born in Kandahar, Afghanistan, moved to Kabul at age three, relocated to Peshawar in Pakistan at thirteen, and immigrated to the United Kingdom at sixteen. He had no identifiable occupational exposure to asbestos, no para-occupational exposure through household contacts, and no memory of living near an asbestos mine. In Britain he worked as a hospital biochemist, an occupation far removed from the traditional asbestos trades. The reporting team, led by Sophie Mounouchos and colleagues writing in Respirology Case Reports, looked instead to his childhood environments, and what they found was a growing body of evidence linking environmental asbestos exposure in Afghanistan and Pakistan to mesothelioma and pleural disease.

In Afghanistan, pleural plaques, thickened patches on the pleura that serve as fingerprints of asbestos exposure, have been reported in a 51-year-old Kabul resident with no occupational exposure. The authors of that report proposed environmental exposure from the neighbouring Loghar region, where natural deposits of tremolite, an amphibole asbestos, have been documented. Kabul also used asbestos-containing materials during the 1970s, including asbestos-cement piping and sheeting. During the 1980s the city suffered repeated structural damage in the Soviet-Afghan conflict, and armed conflict may have mechanically disrupted those materials, releasing airborne fibres, although the researchers caution that the importance of this mechanism remains uncertain.

Pakistan may have added a second layer of exposure. Peshawar lies within Khyber Pakhtunkhwa province, which contains ninety percent of Pakistan’s naturally occurring asbestos deposits, and asbestos-containing construction materials remain widely used in the country. A case series has identified a heavy burden of malignant mesothelioma in the region, thought to be associated with the high concentration of asbestos deposits, and concern about rising diagnoses in younger people is reinforced by a 2011 report of a 26-year-old woman in northern Pakistan diagnosed with the disease despite no occupational exposure. The interval between the patient’s early childhood residence in Kabul and Peshawar and his diagnosis at age forty sits squarely within the recognised latency periods for mesothelioma, lending biological plausibility to the proposed pathway.

The case also illuminates the role of genetics. The environmental mesothelioma outbreak in Turkey linked to erionite, an asbestiform mineral, revealed familial clustering and indirectly led to the identification of the BAP1-associated tumour predisposition syndrome. In a United States cohort of 198 mesothelioma patients, twelve percent carried susceptible germline mutations, notably among younger patients, and BAP1 accounted for only a quarter of the pathogenic mutations found across thirteen cancer-susceptibility genes. Because broader germline testing was not performed in the London case, inherited susceptibility cannot be fully excluded. Together these threads suggest that mesothelioma in the young may represent a distinct entity, with environmental exposure and genetic predisposition interacting in ways that differ from the classic occupational disease of older men.

The implications reach well beyond a single patient. In the United Kingdom, the decline of heavy industry and progressively stricter exposure legislation have driven occupational mesothelioma deaths downward, bringing environmental exposures into sharper focus. While men bear the bulk of disease across all ages, reflecting their historically greater occupational exposure, the gender distribution among those diagnosed under forty is far more even, hinting that other causal factors dominate in the young. The authors argue that clinicians in high-income countries should consider earlier-life environmental and residential exposures acquired overseas, particularly in younger mesothelioma patients who lack conventional occupational histories. Migration to high-resource healthcare settings, they suggest, may be an important mechanism for recognising environmental mesothelioma that would otherwise go undiagnosed in lower-resource settings, and understanding the interplay between inherited susceptibility and environmental fibre exposure may prove essential to unravelling this rare and devastating cancer in the young.

Subject of Research: Environmental asbestos exposure and early-onset malignant pleural mesothelioma

Article Title: Environmental Asbestos Exposure as a Possible Pathway to Early‐Onset Pleural Mesothelioma: A Case From Afghanistan and Pakistan to London

Article References: Environmental Asbestos Exposure as a Possible Pathway to Early‐Onset Pleural Mesothelioma: A Case From Afghanistan and Pakistan to London. (n.d.). https://doi.org/10.1002/rcr2.70774

Image Credits: AI Generated

DOI: 10.1002/rcr2.70774

Keywords: mesothelioma, asbestos, environmental exposure, Afghanistan, Pakistan, pleural effusion, BAP1, genetic susceptibility, early-onset cancer, immunotherapy, tremolite, Khyber Pakhtunkhwa