Abstract Introduction Synchronous primary lung cancers of distinct histologies are exceedingly rare, comprising fewer than 1% of all lung cancer diagnoses. Distinguishing them from intrapulmonary metastases is critical, as this distinction fundamentally alters staging, prognosis, and treatment intent. This case highlights how deliberate diagnostic evaluation and multidisciplinary coordination established dual primary malignancies in a patient whose curative options were limited by severe obstructive physiology. Case Description A 67-year-old woman with over 50 pack-year smoking history, emphysema, and multiple cardiovascular comorbidities presented with progressive dyspnea and was admitted with community-acquired pneumonia. Chest imaging incidentally revealed two distinct pulmonary lesions: a 1.9-cm left upper lobe and a 2.5-cm right lower lobe mass. Follow-up PET/CT confirmed both to be intensely hypermetabolic. Given their differing morphology and metabolic profiles, tissue sampling of each lesion was pursued. Endobronchial ultrasound-guided biopsy of the left upper lobe identified small cell carcinoma, while CT-guided biopsy of the right lower lobe demonstrated non-keratinizing squamous cell carcinoma, confirming synchronous early-stage primary lung cancers. Pulmonary function testing performed several months later revealed severe obstructive physiology (FEV1 33% predicted, FEV1/FVC 32%) with marked hyperinflation (RV 168%, TLC 117%) and diffusion impairment (DLCO 57%), rendering her a poor surgical candidate. A multidisciplinary care plan was subsequently developed, and radiation oncology evaluation was undertaken in collaboration with pulmonology and thoracic surgery to explore non-surgical treatment options while optimizing the patient’s respiratory function. Discussion The coexistence of small cell and squamous cell carcinomas within the same patient is exceptionally uncommon and diagnostically challenging. Without dual-site sampling, this presentation could have been mistaken for metastatic disease, resulting in overstaging and inappropriate systemic therapy. Chronic tobacco exposure likely contributed through a “field cancerization” effect, producing genetically distinct clonal populations. Emerging molecular data reveal divergent mutational profiles—particularly in PI3K–Akt and MAPK pathways—across synchronous tumors, confirming their independent origins. In this case, physiologic inoperability rather than oncologic stage dictated management. The multidisciplinary team’s early involvement allowed transition from surgical planning to radiation-based therapy, preserving disease control while respecting functional constraints. Conclusion This case demonstrates how histologic confirmation of each lesion and early multidisciplinary collaboration are essential for accurate staging and individualized management. It underscores that even early-stage, potentially curable disease may become non-surgical when severe obstructive physiology limits intervention. This abstract is funded by: None
Jagra et al. (Fri,) studied this question.
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