Adult-onset Williams-Campbell syndrome: Clinical presentations, diagnostic challenges, and treatment approaches.

Williams-Campbell syndrome (WCS), traditionally recognized in childhood, is a rare congenital disorder characterized by subsegmental bronchial cartilage deficiency, leading to bronchiectasis. However, its occurrence in adults presents unique diagnostic complexities. We present two cases: Case 1, a 53-year-old male with recurrent rhinosinusitis and COVID-19-associated lung cysts; Case 2, a 59-year-old cyclist with pulmonary bullae. Diagnostic evaluations included pulmonary function tests and imaging studies. Both cases underwent extensive diagnostic evaluations before WCS diagnosis. Management was focused on symptom alleviation and pneumococcal vaccination. Adult-onset WCS poses diagnostic challenges, often mimicking other respiratory conditions. Pathology confirmation is a gold standard for definitive diagnosis; however, in the case of WCS, the literature supports a diagnostic approach primarily based on clinical and radiological findings. Early recognition and tailored management strategies are essential to enhance patient outcomes.