The “drunken honeycomb” feature of pulmonary mucinous adenocarcinoma: A diagnostic pitfall of bronchial brushing cytology

Abstract

Pulmonary mucinous adenocarcinoma (PMA) is the terminology recently proposed in the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) International Multidisciplinary Classification of Lung Adenocarcinoma Guidelines for most tumors previously classified as mucinous bronchioloalveolar carcinomas (mBACs). PMA is histologically characterized by lepidic growth and at least some degree of invasive growth of goblet or columnar neoplastic cells with abundant intracytoplasmic mucin. We report here the cytologic features of PMA in a bronchial brushing specimen. The patient is an 84-year-old woman with a persistent dense consolidation in the right middle lobe of the lung found on non-contrast computed tomography (CT) scan. Bronchial brushing smears showed a monotonous population of columnar neoplastic cells forming "drunken honeycomb"-like cell clusters. The neoplastic cells displayed inconspicuous cytologic atypia. The concurrent transbronchial tissue biopsy and the resection specimen confirmed the diagnosis of PMA. Due to the bland nuclear features, the neoplastic cells in the bronchial brushing specimen were interpreted as benign at the time of the initial diagnosis, demonstrating a diagnostic pitfall of bronchial brushing cytology. A high index of suspicion is recommended when a lung lesion with "drunken honeycomb"-like cell clusters is encountered in bronchial brushing specimens. The review of the literature regarding the recently designated PMA is presented.

Reliability of small biopsy or cytology for the diagnosis of pulmonary mucinous adenocarcinoma

“…The bland nuclear features may prove problematic in recognising the tumours as malignant, particularly in cytologic preparations 2. Cytologically, MA is characterised by ‘drunken honeycomb’-like clusters comprised of monotonous tall columnar epithelial cells with sharply delineated cell borders, unevenly distributed nuclei, abundant cytoplasmic mucin and basally located nuclei.…”

“…Cytologically, MA is characterised by ‘drunken honeycomb’-like clusters comprised of monotonous tall columnar epithelial cells with sharply delineated cell borders, unevenly distributed nuclei, abundant cytoplasmic mucin and basally located nuclei. Mucinous material, necrotic debris and inflammation can be seen in the background 2. In that situation where initial H&E staining sections may not be diagnostic, deeper cuts, strategically made with extra unstained slides for potential molecular studies, may reveal a definitive diagnosis of MA 2.…”

“…Mucinous material, necrotic debris and inflammation can be seen in the background 2. In that situation where initial H&E staining sections may not be diagnostic, deeper cuts, strategically made with extra unstained slides for potential molecular studies, may reveal a definitive diagnosis of MA 2. For example, non-diagnostic alveolar mucin pools with a differential diagnosis of colloid pattern of adenocarcinoma versus mucus plugging in initial sections could be clearly adenocarcinoma with deeper sections.…”

“…This may be caused by the distinct pathologic feature of MA. In other words, the diagnosis of invasive MA can be suspected based on small biopsy and cytology specimens if tumour is present, regardless of cellularity 2 17…”

“…MA exhibits distinctive morphology with lepidic growth, and at least some degree of invasive growth of goblet or columnar neoplastic cells with abundant intracytoplasmic mucin; however, cytologic atypia is usually mild to moderate or may be absent in some cases,1 causing a diagnostic pitfall in recognising MA in small tissue biopsy and cytology specimens 2…”