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A4043 - The New Miliary Kid on the Block
Author Block: W. Kareem1, U. Chaddha1, R. Mahdavi1, T. Ahmadi2, P. Belur2; 1Pulmonary and Critical Care, University of Southern California, Los Angeles, CA, United States, 2Department of Internal Medicine, University of Southern California, Los Angeles, CA, United States.
Miliary lung opacities arise due to a variety of etiologies such as infection, inflammation, and malignancy. Miliary intrapulmonary carcinomatosis (MIPC) has previously been described secondary to metastasis of extrathoracic malignancies. Though a rare presentation, non-small cell lung cancer (NSLC), specifically adenocarcinoma, is also associated with MIPC. Interestingly, these patients are concomitantly identified to have epidermal growth factor receptor (EGFR) mutations (deletion Exon 19) and demonstrate increased treatment response to EGFR tyrosine kinase inhibitors (TKIs). The combination of NSCLC MIPC and EFGR deletion therefore, potentially represents a distinct subgroup of NSCLC patients who may benefit from early EFGR-TKI therapy.
A 46 year old woman with no prior medical history presented with 3 months of worsening cough, chills and night sweats. The patient had no history of respiratory illness, tobacco use, environmental or occupational exposures. Physical examination and routine laboratory studies were unremarkable. Chest x-ray showed numerous scattered micronodular densities. Chest computed tomography confirmed diffuse micronodules throughout both lung fields and revealed a left hilar conglomerate of lymph nodes with left lower lobe consolidative opacity extending to the hilum. Human immunodeficiency virus testing, sputum for acid-fast bacilli and endemic fungal serologies were negative.
The patient underwent bronchoscopy with bronchoalveolar lavage (BAL) and random transbronchial biopsies. Cytology from the BAL demonstrated atypical cells. Endobronchial ultrasound-guided transbronchial needle aspiration revealed atypical cells at station 11R. Pathology review and immunohistochemistry studies were consistent with pulmonary adenocarcioma. Gene sequencing identified an EGFR Exon 19 deletion mutation.
Magnetic resonance imaging (MRI) of the brain revealed multiple subcentimeter enhancing lesions within the brain parenchyma consistent with metastases. The patient was diagnosed with stage IV lung adenocarcinoma (T4N3M1c). The patient was started on erlotinib and underwent whole brain radiation therapy. Subsequent imaging has shown decrease in the patient’s intrathoracic tumor burden and good response to whole brain radiation therapy.
MIPC is an infrequent manifestation of primary pulmonary malignancies. MIPC is most often associated with pulmonary adenocarcinoma and these patients have associated EGFR exon 19 deletions making them prime candidates for EGFR TKIs. Because EGFR signaling regulates the synthesis and secretion of several angiogenic growth factors such as vascular endothelial growth factor, interleukin-8, and basic fibroblast growth factor, malignancies with EGFR mutations tend to develop angiogenic metastases. MIPC may represent an additional subgroup. Interestingly MIPC occurs most often in non-smoking Asian females. Physicians should consider upfront EGFR-TKI therapy due to their responsiveness; however, larger studies are needed to confirm this.