ADENOCARCINOMA OF THE LUNG WITH A MILIARY PATTERN

Abstract

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: A miliary pattern on chest imaging is often concerning for primary tuberculosis. However, such nodules may also be seen in fungal infections and autoimmune or (rarely) metastatic processes. Here, we report a case of a miliary mottling on chest imaging associated with metastatic lung adenocarcinoma. CASE PRESENTATION: A 39-year-old man with a history of obesity and tobacco use presented with worsening chest congestion and dyspnea on exertion for 2 months. He had occasional wheezing without associated symptoms, including fever, chills or night sweats, or weight loss. He worked in environmental services without any known sick contacts or recent travel history. Physical examination was unremarkable except a small, palpable right supraclavicular lymph node. The initial chest x-ray showed diffuse interstitial infiltrates. Chest CT revealed innumerable bilateral cavitary nodules with an apical gradient, a right lower lobe 6-cm mass with cavitation, and mediastinal and supraclavicular lymphadenopathy. Given concern of pulmonary tuberculosis with a miliary component, the patient remained on airborne precautions. Laboratory workup was notable for a mild leukocytosis of 12,000. Sputum cultures and AFB staining were negative. A baseline connective tissue panel, AFP, and beta-hCG levels were unmeasurable. Given his age and concern for metastatic disease, a scrotal ultrasound was performed but did not reveal any testicular mass. Subsequently, the patient underwent a fine-needle aspiration and core biopsy of the right supraclavicular lymph node, which showed metastatic adenocarcinoma. The immunohistochemical profile was suggestive of a positive CK7 but negative for CK20, TTF-1, CDX2, and Napsin A---support the diagnosis of non-small cell lung cancer with a KRAS Q61K mutation. Immuno-chemotherapy with a combination of carboplatin, pemetrexed, and pembrolizumab was initiated, given his stage IV metastatic lung adenocarcinoma. DISCUSSION: The differential diagnosis for miliary patterns on chest imaging includes tuberculosis, fungal infections, sarcoidosis, pneumoconiosis, and secondary metastasis. Miliary-pattern metastatic lung adenocarcinomas have been rarely reported. Our case is of interest given the negative TTF-1 with a KRAS Q61K mutation, the later of which is associated with resistance to the EGFR inhibitors gefitinib and erlotinib. This entity is thought to have a poorer prognosis than KRAS wild-type adenocarcinomas. CONCLUSIONS: The initial radiologic presentation of these cases can be misleading in areas with high prevalence of infections such as tuberculosis and fungal infections. The possibility of primary lung cancer should also be considered in these cases. Reference #1: A. Sekine et al., “Miliary lung metastases from non‑small cell lung cancer with Exon 20 insertion: A dismal prognostic entity: A case report,” Mol. Clin. Oncol., Oct. 2018, doi: 10.3892/mco.2018.1730. Reference #2: L. Kimmig and J. Bueno, “Miliary Nodules: Not Always Tuberculosis,” Ann. Am. Thorac. Soc., vol. 14, no. 12, pp. 1858–1860, Dec. 2017, doi: 10.1513/AnnalsATS.201706-436CC. Reference #3: P. J. Roberts, T. E. Stinchcombe, C. J. Der, and M. A. Socinski, “Personalized medicine in non-small-cell lung cancer: is KRAS a useful marker in selecting patients for epidermal growth factor receptor-targeted therapy?,” J. Clin. Oncol., vol. 28, no. 31, pp. 4769–77, Nov. 2010, doi: 10.1200/JCO.2009.27.4365. DISCLOSURES: No relevant relationships by Kamran Manzoor, source=Web Response No relevant relationships by Eric Robbins, source=Web Response No relevant relationships by Ajit Thota, source=Web Response