Metastatic pleural effusion: a rare presentation of salivary gland adenoid cystic carcinoma. 
Adenoid cystic carcinoma, an uncommon malignant salivary gland neoplasm, is known for its long clinical course, indolent growth, local recurrence and late distant metastasis.  We report an unusual case of adenoid cystic carcinoma of the palate in a 64-year-old woman, undiagnosed for more than 15 years, who presented as malignant pleural effusion.