When Observation Became Evidence: The Enduring Value of Case Reports in Clinical Medicine (Anuradhapura Medical Association Oration 2025)

Case reports and case series have long been the foundation of clinical observation, serving as crucial signals for new diseases, unusual manifestations of known conditions, rare adverse drug reactions, and unforeseen complications. This review illustrates how bedside observations become scientific evidence, highlighting discoveries that shaped medical understanding across infectious, toxicological, nephrological, and genomic domains. One early example described a patient with tuberculosis-associated autoimmune haemolytic anaemia (AIHA), a rare but significant immune-mediated complication. Our systematic review confirmed that while AIHA is uncommon, TB-induced AIHA is even rarer, with distinctive clinical and laboratory profiles. In contrast, tuberculous pericarditis represents another immunopathological spectrum, driven not by antibodies but by delayed-type hypersensitivity, leading to characteristic haemorrhagic, non-clotting pericardial effusions. Recognition of these distinct immunological pathways has direct therapeutic implications, including the use of steroids as adjuvants in pericarditis but not always in AIHA. Another set of bedside observations arose from an environmental disaster at a glove manufacturing plant in Sri Lanka, where workers developed acute systemic symptoms traced to latex transported in barrels previously containing toluene diisocyanate. This investigation uncovered previously unreported muscle involvement in isocyanate toxicity, echoing historical examples of tri-cresyl phosphate–related neuropathy and underscoring the dangers of chemical container reuse. Turning to nephrology, the search for the cause of chronic interstitial nephritis among agricultural communities (CINAC) has been shaped by case reports that helped avoid blind alleys. An exertional heat stroke case in a young military trainee initially suggested that repeated subclinical heat stress might underlie CINAC; however, biomarker studies in children and systematic reviews challenged this hypothesis, pointing instead toward environmental toxins as primary drivers, with heat as an aggravating factor. Further prospective studies, such as the Anuradhapura Snakebite Cohort, clarified that while snake envenoming causes acute kidney injury, it does not contribute to CINAC, with chronic kidney disease in this population more strongly linked to comorbidities and environmental exposures. A series of patients with distal renal tubular acidosis co-existing with Southeast Asian ovalocytosis in Rajarata provided another window into tubular disorders, revealing genetic underpinnings in SLC4A1 mutations but also prompting comparisons with CINAC, where histopathology suggests toxin-induced proximal tubular injury akin to calcineurin inhibitor nephrotoxicity. Finally, observations at the bedside of young patients with necrotising pneumonia led to genomic investigations that traced a highly virulent, Panton-Valentine leukocidin–positive MRSA clone circulating in Sri Lanka and globally. Whole-genome sequencing demonstrated its dominance across both community and healthcare settings, linking clinical severity with molecular epidemiology and highlighting blurred boundaries between hospital- and community-acquired infections. Attentive clinical observation, when combined with systematic follow-up and modern tools, can transform individual case reports into evidence that advances medical understanding. Such reports bridge bedside practice with scientific discovery, shaping research, therapy, and health policy.