Simone Barry

INTRODUCTION Pulmonary Langerhans cell histiocytosis (PLCH) is a rare form of interstitial lung disease with an estimated prevalence of 1–2 per million.1 It shares histologic features with other forms of Langerhans cell histiocytosis (LCH) which can affect multiple organs and remains largely of unknown aetiology.2 Unlike LCH, which is primarily seen in children, PLCH predominantly occurs in young adults, particularly in those who currently smoke, and is largely confined to the lungs.

Keywords Post-acute COVID-19 syndrome (PACS) Persistent symptoms COVID-19 Non-COVID-19 respiratory illness Symptom severity Symptom duration Age Chronic respiratory disease Pre-existing symptoms Healthcare workers Symptom patterns Prospective data Multicentre study RESEARCH IN CONTEXT Many studies of long COVID-19 have been limited by methodological issues.

In an historical narrative dating back to the 10th century, the renowned Persian physician and philosopher, Avicenna, astutely observed a correlation between tuberculosis (TB) and diabetes, shedding light on a medical association that continues to shape our understanding of these complex diseases.1 The introduction of insulin in 1922 marked a pivotal moment, yet for many type 1 diabetes patients who survived a diabetic coma, TB remained a significant cause of mortality.