Primary pulmonary adenoid cystic carcinoma- clinicopathological features and predictors of poor outcome.

Introduction: Primary pulmonary adenoid cystic carcinoma is a rare disease. Its clinico-pathological features, course of disease, therapeutic strategy, and survival data have not been fully elucidated. We aimed to study the clinicopathological characteristics of primary pulmonary adenoid cystic carcinomas in north India.

Methods: This study was a retrospective, single-centre, cohort study. The database of the hospital was searched for a period of seven years to identify all patients with primary pulmonary adenoid cystic carcinoma.

Results: Out of 6050 lung tumors, 10 were primary adenoid cystic carcinomas. The mean age of diagnosis was 42 (±12) years. Six patients had the lesion in the trachea, main bronchus or truncus intermedius and four had parenchymal lesions. Seven patients had resectable tumours. Three patients achieved an R0 resection, two achieved R1 resection and two had R2 resection. On histopathological examination, almost all of the patients had cribriform pattern. Only four patients (57.1%) showed positivity for TTF-1 staining. The five-year survival of patients with resectable tumour and un-resectable tumour was 85.7% and 33.3%, respectively (P = 0.01). The predictors of poor outcome included non-operability of the tumour, presence of metastasis at the time of diagnosis, and macroscopically positive tumour margin during surgery.

Conclusion: Primary pulmonary adenoid cystic carcinoma is a unique and rare tumour that affects relatively younger individuals, males and females, as well as smokers and non-smokers equally. The features of bronchial obstruction are the most common. Surgery is the primary modality of treatment and completely resectable lesions have the best prognosis.