Congenital Pulmonary Airway Malformation – A Histomorphological Spectrum of 15 Cases: A 5-Year Study from a Tertiary Care Center

OBJECTIVE: Congenital pulmonary airway malformation (CPAM) is a rare developmental lung disease. The aim of this study is to analyze the histomorphological spectrum of CPAM in a series of 15 cases. MATERIALS AND METHODS: A retrospective descriptive study of 15 cases of CPAM was carried out from 2013 to 2018 in our hospital, and cases were classified based on the Stocker's classification. RESULTS: The age ranged from 4 days to 9 years (66.6% were infants). The left lung was most commonly involved (66.6%). The most common lobe was the left upper lobe (60%), followed by right lower lobe (20%). Grossly, cysts measured 0.2–5 cm, filled with mainly serous fluid with few having hemorrhagic and brownish mucoid secretions. On microscopy, single to multiple noncommunicating cysts of size 0.2–5 cm were seen, lined by ciliated columnar epithelium (60%), pseudostratified ciliated columnar epithelium (26.7%), mucin-secreting columnar epithelium (6.7%), and flattened epithelium (6.7%). Few cases showed smooth muscle (20%) and cartilage (13.3%) in the cyst wall. Chronic inflammation (73.3%) with dense histiocytic infiltrate (13.3%) was also seen. Emphysematous changes were also observed (13.3%). Cytomegalovirus inclusions (6.7%), zygomycete fungus (6.7%), and red hepatization (6.7%) were observed. The most common type was type II (60%), followed by type I (33.3%) and type IV (6.7%). CONCLUSION: Type II was the most common variant in this study. A careful observation should be done to look for fungal hyphae or viral inclusions.