Malignant pleural effusion and pericardial effusion, an unusual presentation of metastatic adenoid cystic carcinoma of the floor of mouth: A case report with cyto-histopathological correlation.

Adenoid cystic carcinoma (ACC) is an uncommon tumour that represents 5%-10% of salivary gland tumours and 1% of all head and neck malignancies. It is characterised by a protracted clinical course with late metastasis and poor long-term prognosis. We report the case of a 38-year-old woman presenting with pulmonary and pleural metastases, on the background of ACC of the floor of mouth, which had been treated 4 years ago with surgical excision and radiotherapy. Cytological evaluation of the pleural effusion showed exfoliated ACC tumour cells. Despite palliative chemotherapy, the patient developed disease progression including metastatic spread to the pericardium, and died of disease within a year. This case illustrates an unusual presentation of ACC and highlights the importance of considering this entity when encountering a basaloid neoplasm in extra-salivary locations.