Gelatinous pleural effusion in advanced lung adenocarcinoma: a case report

Gelatinous pleural effusions, a rare subtype of exudative effusions with elevated viscosity due to high hyaluronic acid levels, are often associated with malignancies, particularly malignant pleural mesothelioma and some metastatic cancers. Such effusions present unique challenges in both diagnosis and management due to their thickness, which complicates drainage using standard techniques. This case highlights the clinical significance of recognizing unusual pleural fluid characteristics and employing advanced drainage interventions, particularly in metastatic lung adenocarcinoma. Given their rarity, gelatinous pleural effusions are not widely reported, emphasizing the need for increased awareness of their diagnostic and therapeutic implications.

A 46-year-old African American female patient with lung adenocarcinoma was admitted with a re-accumulating pleural effusion that required further intervention. A Pleurex catheter was placed for continuous drainage, revealing a gelatinous, coagulated effusion that resisted standard drainage techniques. An initial 250 mL of fluid was removed, followed by an additional 1.2 L after intrapleural hyaluronidase was administered to break down the viscosity. Cytology confirmed the presence of malignant cells, positive for CK-7 and TTF-1, and negative for calretinin, Ber-EP4, and CK-20, supporting the diagnosis of primary lung adenocarcinoma. Despite successful fluid removal, imaging indicated a trapped lung, preventing full re-expansion of the pleural space. The patient's care was transitioned to home management with intermittent Pleurex catheter drainage and palliative care support, with plans for outpatient follow-up and ongoing monitoring.

This case underscores the complexities associated with managing gelatinous pleural effusions, particularly in the context of malignancy. The patient's palliative management, including the use of an indwelling pleural catheter, highlights the focus on symptom relief in advanced disease stages. Recognizing gelatinous pleural effusions as a potential diagnostic indicator, particularly in patients with malignancies, can facilitate timely interventions that may improve quality of life. Continued research and clinical awareness are essential to optimize diagnostic approaches and treatment options for these rare, challenging effusions.