Bronchial Brushing Cytologic Finding of Primary Pulmonary Adenoid Cystic Carcinoma Misinterpretated as Small Cell Carcinoma: A Case Report with Literature Review

ABSTRACT

An adenoid cystic carcinoma is a very rare primary pulmonary neoplasm. Bronchial washing and brushing cytological findings of pulmonary adenoid cystic carcinoma have rarely been described. Here, we report the bronchial brushing cytological findings of an adenoid cystic carcinoma, finally diagnosed in a 71-year-old female patient. The low-power view showed moderate cellularity and cohesive clusters of small to medium-sized cells. The high-power view revealed distinct nuclear moldings, a coarse chromatin pattern, and inconspicuous nucleoli, which was favorable to a diagnosis of small cell carcinoma. However, apoptotic bodies, nuclear debris, and mitoses were not seen frequently. The bronchial biopsy showed solid, trabecular, and cribriform patterns in small cells. Periodic acid Schiff staining disclosed globular basement membrane-like materials, and the immunohistochemical staining revealed the presence of myoepithelial cell components, strongly suggestive of a salivary gland type tumor, compatible with an adenoid cystic carcinoma. In this report, we describe the exfoliative cytological features of a pulmonary adenoid cystic carcinoma with emphasis on some diagnostic pitfalls.