Abstract Introduction Pleomorphic carcinoma is a rare, aggressive subtype of non-small cell lung cancer, accounting for less than 1% of pulmonary malignancies. It is characterized by a combination of spindle and/or giant cells with epithelial components, often presenting with nonspecific symptoms and rapidly progressive disease. Diagnosis is challenging due to overlapping histopathological and immunohistochemical features with other pleural malignancies, such as mesothelioma. Pleural malignancies remain among the most challenging conditions encountered in pulmonary medicine due to their nonspecific presentation and complex diagnostic process required to establish a definitive etiology We present a case highlighting the diagnostic complexity and poor prognosis associated with pleomorphic carcinoma presenting as a malignant pleural effusion. Case Description Case of a 72-year-old male who came to the emergency department with shortness of breath and dyspnea for two weeks. Initial evaluation revealed hypotension, leukocytosis, and left side decreased breath sounds. Chest Computed Tomography (CT) showed large-left sided pleural effusion with abnormal pleural nodularity. Inflammatory markers were elevated. Chest tube was placed due to suspected malignancy and exudative composition as per Light’s criteria. Patient averaged 1.5 liter output daily with slow resolution of his pleural effusion. Initial pathology revealed immunostains positive for Pankeratin suggesting a mesothelial lesion concerning for Mesothelioma. Interventional Radiology was consulted for biopsy of lung base pleural mass. Results showed cells composed by spindle-cells with pleomorphic nuclei. PET-CT scan showed FDG concentration with central focal defect suggesting necrosis on the left lung with increased tracer uptake corresponding to lobulated thickening pleural segments as seen in prior CT (Figure 1). Biopsy was sent for a second evaluation to further characterization. The pleural effusion evolved into an Empyema requiring mechanical ventilation and vasopressors. Improvement of pleural effusion showed complete opacification of the left mainstem bronchus. Bronchoscopy endobronchial washing and biopsy was performed showing Poorly Differentiated Carcinoma with suspected Pleomorphic carcinoma vs spindle-cell carcinoma. Immunostains positive for CK7, PANKERATIN, CK19, WT1. Final secondary evaluation of lung pleural core biopsy confirmed our diagnosis but patient was pronounced deceased 24 hours later. Discussion This case demonstrates the profound diagnostic and therapeutic challenges of defining pleural based malignancies. Overlapping cytological and immunohistochemical can delay definitive diagnosis, limit timely intervention, and delay treatment. Persistent malignant effusions further predispose to infection and respiratory compromise, contributing to poor outcomes. Early multidisciplinary evaluation, comprehensive tissue sampling, and refinement of diagnostic pathways are critical to improving survival and quality of life in patients with suspected pleural malignancy. This abstract is funded by: None
Choudens et al. (Fri,) studied this question.