Pulmonary Hydatid Disease: Classical Cytological Features and Key Differentiators from Mimics

A 45-year-old female with a history of livestock exposure presented to our tertiary care centre with progressive shortness of breath and dry cough for one year. There were no systemic signs of illness, and vitals were stable. Routine blood investigations were normal. Chest radiography showed a large, well-defined lesion in the left mid and lower lung zones with a characteristic acute angle to the pleura, suggestive of a pulmonary cyst. Cytological examination of the cyst fluid revealed numerous scolices, rostellum with hooklets, and calcific spherules. Histopathological analysis showed a lamellated, hyalinized cyst wall with fibrin and haemorrhage along with an inflamed pericyst. This case highlights a pulmonary hydatid cyst, managed successfully with a minimally invasive right posterolateral thoracotomy. The classical cytological characteristic features not only help confirm the diagnosis but also aid in differentiating it from other mimics.