Abstract
INTRODUCTION AND IMPORTANCE: Lung adenocarcinoma may resemble the clinical presentation of an infectious or inflammatory lung disease. The coexistence of lung cancer, and polyserous effusions is uncommon, which may cause a diagnostic challenge. However, any polyserous effusions at a young age must always be suspicious for malignancy. CASE PRESENTATION: We report a case of 38-year-old male patient with polyserous effusions and pneumonia who was treated accordingly and showed clinical improvement with a significant reduction of pericardial and pleural effusions. Subsequent testing and a biopsy resulted in the histopathological diagnosis of an adenocarcinoma of the lung. CLINICAL DISCUSSION: Nonrecurrent polyserous effusions in lung adenocarcinoma are uncommon, and negative cytology results may not exclude malignancy due to the moderate sensitivity of pleural and pericardial fluid cytology. Clinicians should remain vigilant for false-negative results, especially in younger patients. Malignancy should not be ruled out because pleural and pericardial fluid cytology have a sensitivity of 60% and 92%, respectively. CONCLUSION: Our case highlights the diagnostic challenges posed by atypical presentations of lung adenocarcinoma and emphasizes the importance of considering malignancy in the differential diagnosis of polyserous effusions, even when initial cytology results are negative. Clarifying the rationale for this study enhances its relevance and impact.