Primary salivary gland-type tumors (SGT) of the lung comprise a very low proportion of pulmonary tumors, accounting for under 1% of all lung tumors [1]. The predilection of lung SGT tumors includes mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ACC), and epithelial-myoepithelial carcinoma [2]. Hyalinizing clear cell carcinoma (HCCC), a rare SGT, has been recently recognized and classified according to the WHO classification of thoracic tumors [1].

HCCC was initially described by Milchgrub et al. [3] as a new low-grade carcinoma located in the head and neck, especially in the minor salivary glands of the oral cavity. These neoplasms are characterized by tumor cells with abundant cytoplasm, stained clear or eosinophilic, arranged in nests, cords, and trabeculae, and embedded in the hyalinizing stroma. HCCC in the lung was first reported in 2015 [4] and shares the histology, immunophenotype, and molecular alteration features with HCCC reported in the head and neck salivary glands. However, its morbidity rate is extremely low. Only twenty-two primary pulmonary HCCC cases have been reported to date [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], and most of them had an indolent course except for one [5]. Moreover, little is known about lung HCCC because of the paucity of reports. Therefore, it is necessary to define the clinicopathological features of pulmonary HCCC by studying more cases.

In this study, we present two primary pulmonary HCCC cases and analyze their clinicopathological characteristics and molecular genetic changes. We reviewed twenty-two previously reported cases to provide a better understanding of the diagnosis and patient outcomes of this rare neoplasm.