Primary lung secretory carcinoma: a case report
Lung salivary gland-like tumors are histolgocaly similar to those found in the major and minor salivary glands of the head and neck region. These primary lung tumors are exceedingly rare, but various types of salivary gland-like carcinomas have been reported in the lung. This case pertains to a 51-year-old female with worsening shortness of breath and cough. Workup revealed a left lung hilar mass which was subsequently resected and diagnosis confirmed to be secretory carcinoma of the lung. The tumor demonstrated classic morphologic features of secretory carcinoma, showing a well-circumscribed mass that is composed of microcystic and glandular spaces with abundant eosinophilic secretions, and diffuse expression of S100 in the absence of immunostaning for TTF1, p40, and neuroendocrine markers. In addition, lymphatic invasion and metastasis to hilar lymph node were present. This case represents only the third case of a primary lung secretory carcinoma. Concurrent molecular testing was confirmatory and showed the ETV6-NTRK3 gene fusion. In conclusion, primary lung salivary gland tumors are rare, but various types of salivary gland carcinomas can be identified in the lung, including secretory carcinoma. As more cases of primary lung secretory carcinoma are reported, this will hopefully lead to increased knowledge of the clinical behavior of this rare primary lung tumor.
