Mucinous carcinoma (colloid carcinoma) of the lung diagnosed by fine needle aspiration cytology: a case report

Mucinous carcinoma of the lung, also known as colloid carcinoma, is an uncommon tumour that is rarely encountered in fine needle aspiration (FNA) cytological practice. A 64-year-old Chinese male presenting with blood stained sputum and hoarseness of voice was discovered to have a 3 cm sized mass in the left lung. Neither bronchial washings nor transthoracic FNA yielded positive results at this stage. Six months later the patient returned to the hospital with a larger tumour and mediastinal lymphadenopathy. Transbronchial lymph node FNA, reported as negative for malignancy showed normal, hyperplastic and mildly atypical bronchial epithelial cells as well as a few single cells and extracellular mucin. Transthoracic FNA of the lung lesion performed under computed tomographic guidance showed characteristic cytological features of this tumour, establishing the diagnosis.