Primary pulmonary adenoid cystic carcinoma: A case report of prolonged survival with late metastatic disease and a brief review of the literature

Primary pulmonary adenoid cystic carcinoma (PACC) is a rare salivary gland–type tumor originating in the central airways. Although indolent, it is nonetheless associated with late local recurrence and distant metastasis.

A 51-year-old woman presented with a 14-month history of intermittent dry cough and progressive exertional dyspnea, followed by wheezing refractory to antibiotics and bronchodilators. Contrast-enhanced chest computed tomography revealed a 2.8-cm well-circumscribed, homogeneous, lobulated intraluminal mass arising from the right mainstem bronchus without mediastinal invasion. Positron emission tomography–computed tomography demonstrated mild-to-moderate fluorodeoxyglucose avidity without nodal or distant metastases. Bronchoscopic biopsy confirmed classic adenoid cystic carcinoma with solid, tubular, and cribriform patterns, pseudocystic spaces, and perineural invasion. Immunohistochemistry (IHC) showed positivity for CK7, p63, SOX10, S100 (myoepithelial markers), and strong membranous CD117 (c-Kit); fluorescence in situ hybridization verified MYB–NFIB gene fusion.

Treatment comprised lung-sparing carinal resection with airway reconstruction, followed by adjuvant external-beam radiotherapy (60 Gy in 30 fractions) for positive margins. Seven years postoperatively, metastatic pulmonary nodules and an iliac bone lesion emerged, initially managed with active surveillance, then lenvatinib systemic therapy and stereotactic body radiotherapy to symptomatic bone metastasis. This case illustrates the diagnostic complexity, protracted natural history, and need for extended multidisciplinary surveillance in PACC.