Acinic cell carcinoma arising in ectopic salivary gland tissue.

Two cases of a rare entity, acinic cell carcinomas, which apparently arose primarily from ectopic salivary gland tissue, are presented. Salivary gland ducts and acini frequently may be found incorporated within intraparotid lymph nodes and less commonly within extraglandular cervical nodes. Ectopic salivary glands may also be seen, although rarely, elsewhere in the head and neck area. The most common tumor to arise from intranodal salivary gland tissue is papillary cystadenoma lymphomatosum; however, other salivary gland-type neoplasms rarely may do so. In our cases, one tumor apparently originated primarily within a paraparotid lymph node and the other in the lateral mid- to low-neck area. Neither of our patients had a demonstrable lesion of a major or minor salivary gland; thus their tumors are presumed to have originated primarily from ectopic salivary gland tissue. The clinician and the pathologist should consider the possibility of a neoplasm arising in ectopic tissue when a salivary gland type tumor is identified away from sites where major and minor salivary glands normally are found.