What question did this study set out to answer?

To illustrate the clinical challenges of synchronous multiple primary lung cancers with different histologies in a patient with a history of tobacco use.

May 20, 2026

C80-34 Synchronous Multiple Primary Lung Cancers With Distinct Histology

Key Points

To illustrate the clinical challenges of synchronous multiple primary lung cancers with different histologies in a patient with a history of tobacco use.
Patient underwent low-dose CT screening and subsequent imaging studies for lung lesions
Navigational bronchoscopy and EBUS-guided biopsy were performed to confirm malignancies
Surgical lobectomy and lymphadenectomy were conducted alongside histological analysis.
First lesion confirmed as stage IA adenocarcinoma with 16 mm size
New left lower lobe nodule identified as NSCLC with squamous differentiation, clinical stage IIA
Presence of unicentric Castleman disease noted as an unrelated process with no malignancy contribution.

Abstract

Abstract Introduction Lung cancer remains the leading cause of cancer-related mortality worldwide. Multiple primary lung cancer (MPLC), defined as the presence of two or more distinct primary tumors within the lungs—either with identical or differing histologies—is a relatively rare but clinically significant entity. Risk factors includes family history and underlying lung disorders, including COPD, A prior history of lung cancer, along with continued tobacco use further elevates the risk of developing a second primary lung malignancy. Case Description A 62-year-old male with a history of tobacco use disorder and COPD underwent low-dose CT (LDCT) for lung cancer screening. Imaging revealed a 10 mm ground-glass opacity (GGO) in the right upper lobe which remained stable from January 2021 through December 2023. Imaging also revealed marked bilateral mediastinal and hilar lymphadenopathy. A mediastinoscopy performed in July 2023 revealed only benign lymph nodes, which remained stable in size and were therefore considered unrelated to malignancy. In December 2023, the right upper lobe lesion showed interval growth to 16 mm and transformation into a more subsolid nodule. Navigational bronchoscopy with cytology confirmed adenocarcinoma, deemed stage IA given a negative 11R lymph node. He subsequently underwent a right upper lobectomy. Surgical pathology revealed a 14 mm, well-differentiated adenocarcinoma with negative resection margins. No adjuvant therapy was indicated. Concurrent lymphadenectomy of stations 7, 9R, 10R, 11R, and 4R was performed, and histologic analysis was consistent with unicentric Castleman disease. The patient tested negative for HIV and HHV-8 and was started on corticosteroids. The patient was counselled on smoking cessation and has trialed medications such as varenicline, but to no avail. Six months postoperatively, surveillance LDCT revealed a new left lower lobe nodule measuring up to 4.4 cm with PET avidity. Endobronchial ultrasound (EBUS)-guided biopsy confirmed non-small cell lung cancer (NSCLC) with squamous differentiation. The 11L lymph node was positive for malignancy, consistent with at least clinical stage IIA (cT2N1). He is currently undergoing evaluation for surgical resection versus definitive chemoradiation. Conclusion This case highlights the complex clinical challenges posed by MPLC, particularly in patients with ongoing tobacco exposure. Smoking cessation remains a critical component to reduce risk of further lung malignancy. It is also important to practice vigilant postoperative surveillance. Presence of unicentric Castleman disease in regional lymph nodes represented an unrelated benign lymphoproliferative process and did not contribute to either malignancy. This abstract is funded by: None

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