What was unusual here? Although our patient had a 16-pack-year history of smoking, it is unusual for the disease to present in adolescents and young adults. The youngest reported case of primary adenocarcinoma of the lung involved a 15 year old, leading researchers to believe that genetic mutation may play a role. In addition, researchers have identified a mutation involving the EGFR gene that may predispose an individual to developing NSCLC.5 Trials are now underway using tyrosine kinase inhibitors, such as gefitinib and erlotinib, to target the tyrosine kinase domain on EGFR.6,7
Differential Dx includes a variety of infections
The differential diagnosis of a lung mass is broad and includes bacterial, fungal, pneumocystic, and granulomatous infections. Cancer, connective tissue diseases, and vascular malformations may also present in this manner. However, our patient also had a pleural effusion, which would lead one to consider cancer or a bacterial infection as a more likely etiology.
In a 26-year-old man, the most common metastatic cancers would include testicular, melanoma, and thyroid cancers. In addition, the typical pattern of metastatic disease of these cancers on chest x-ray is that of bilateral, multiple, round, and well-circumscribed lesions, which was not the case with our patient.
Pleural fluid analysis holds key to diagnosis
Making the diagnosis of lung cancer—particularly in a younger population—requires a high level of suspicion. A delay in diagnosis leads to a poor prognosis. Symptoms and clinical findings should direct the diagnostic process.
In our patient, the diagnosis was particularly challenging because he had no presenting pulmonary symptoms and the work-up was directed by findings on exam. Pleural effusions are present in up to one-third of patients with NSCLC at the time of presentation,8 as was the case with our patient. Analysis of pleural fluid or tissue is required to confirm the diagnosis of NSCLC.