PP21 CYSTIC, ELUSIVE AND DEADLY? FIVE YEARS OF DIFFUSE CYSTIC LUNG DISEASE AT TERTIARY CENTRE

Nor Syamimi Mohd Isa, Noor Eliana Rozani, Ahmad Adib Nasir, Haly Rozie Ahmad, Fatimah Azmah Mohammad, Leong Swee Wei, Mona Zaria Nasaruddin and Noorul Afidza Muhammad

Hospital Sultan Idris Shah, Serdang

Background
Diffuse cystic lung disease (DCLD) comprises a diverse group of rare pulmonary disorders characterized by multiple lung cysts, with overlapping imaging features and varying clinical trajectories. This study aimed to describe the clinical profiles, functional outcomes, and survival patterns of DCLD subtypes managed at a Malaysian tertiary centre over five years.

Methods
A retrospective review was conducted at Hospital Sultan Idris Shah Serdang from March 2020 to May 2025. All diagnoses were established through high-resolution CT imaging and confirmed via multidisciplinary discussion (MDD), with histopathological or genetic support where applicable. Clinical data, lung function, treatment, and outcomes were analyzed. Kaplan-Meier analysis was used to estimate overall and oxygen-free survival.

Results
Fifteen patients were identified: lymphangioleiomyomatosis (LAM, n=5), Birt-Hogg-Dubé syndrome (BHD, n=7), pulmonary Langerhans cell histiocytosis (PLCH, n=2), and autoimmune-associated lymphoid interstitial pneumonia (LIP, n=1). The mean age was 44.8 years, with 73.3% female. Pneumothorax was a common initial presentation (53.3%). All BHD patients had preserved lung function (FEV₁ and FVC >80%) and remained stable, consistent with the typically mild pulmonary involvement described in literature. Three LAM cases had histological confirmation, and four received sirolimus with clinical stabilization, mirroring outcomes from the MILES trial. Two LAM patients and one PLCH patient progressed to long-term oxygen therapy; the PLCH patient later died. Two deaths occurred during follow-up. Kaplan-Meier analysis estimated 5-year overall survival at 86.7% and oxygen-free survival at 80%.

Conclusion
This study highlights the clinical heterogeneity of DCLD and the value of multidisciplinary discussion in accurate diagnosis. While BHD showed a benign course, LAM and PLCH demonstrated potential for progression. These findings are consistent with existing evidence and underscore the importance of early phenotypic classification, targeted therapy, and individualized long-term follow-up in DCLD management.