Cytology of primary salivary gland-type tumors of the lower respiratory tract: report of 15 cases and review of the literature

Primary pulmonary salivary gland-type tumors are rare neoplasms arising from the
seromucinous submucosal glands of the lower respiratory tract (LRT), the most common
of which are mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma. They are
morphologically indistinguishable from their salivary gland counterpart and recognizing
them is a challenge, especially on cytological specimens. We analyzed 15 cases of histologically
proven primary salivary gland tumors of the LRT to identify cytomorphological
features and define potential diagnostic clues that might assist cytopathologists in the
preoperative diagnosis of these neoplasias. Three out of the four cases of adenoid cystic
carcinomas showed the characteristic tridimensional cell clusters and hyaline globules,
whereas the last one did not show malignant cells; only two cases of MEC presented
the three characteristic cell types (i.e., squamous, intermediate, and mucin secreting)
on cytology. Since these neoplasms are rare and do not have a completely specific set
of cytological features, it is important for practicing cytopathologists to be aware of the
possibility of encountering them, in specimens from patients with LRT masses, in order
to render the correct diagnosis.