Gelatinous pleural effusion in advanced lung adenocarcinoma: a case report

Our plain-English summary of Gelatinous pleural effusion in advanced lung adenocarcinoma: a case report, by J. Sutton, Y. Grabie, D. Rotblat, et al (Journal of Medical Case Reports, 2025).

The study

• Authors: J. Sutton, Y. Grabie, D. Rotblat, H. El-Hage
• Journal: Journal of Medical Case Reports
• Published: 2025;19(1):407
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Background: 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.

Case Presentation: 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.

Conclusions: 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.

© 2025. The Author(s).

In plain English

This case report described one patient, a 46-year-old African American woman with no smoking history, who was diagnosed in August 2024 with stage IV adenocarcinoma of the right lung. A first drainage removed 1.5 L of cloudy, blood-tinged fluid from around the lung. The fluid contained cancer cells, and lymph node biopsies confirmed adenocarcinoma originating in the lung. The fluid built up again. When a Pleurex catheter (a drainage tube left in place) was inserted, the fluid was thick and gelatinous and resisted drainage by standard techniques. About 250 mL came out at first, and another 1.2 L after the enzyme hyaluronidase was placed into the chest cavity. Imaging then showed a trapped lung, suggesting the pleural space could not fully re-expand. The authors concluded that hyaluronidase helped drainage when standard techniques failed, and that unusual pleural fluid can be a diagnostic clue. Asbestos and pleural mesothelioma appear only in the authors' background discussion. The article does not report whether this patient had any asbestos exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report (a single patient)
• Who was studied: One 46-year-old African American woman diagnosed in August 2024 with stage IV adenocarcinoma of the right lung
• Exposure: No asbestos exposure is reported for this patient. Asbestos is mentioned only in background discussion of mesothelioma. The patient had no smoking history.
• Main results:
  • The first drainage of the right chest removed 1.5 L of cloudy, serosanguineous (blood-tinged) fluid, and cytology showed malignant cells.
  • Lymph node biopsies showed adenocarcinoma with immunohistochemical staining positive for TTF-1 and napsin A, confirming a lung origin.
  • The cancer was staged T4, N3, M1a.
  • The pleural effusion re-accumulated after the first drainage.
  • When the Pleurex catheter was inserted, the fluid was gelatinous and resisted standard drainage techniques. Approximately 250 mL was removed at first.
  • An additional 1.2 L was removed after hyaluronidase was instilled into the pleural space.
  • Pleural fluid studies showed an exudative effusion by Light's criteria.
  • Imaging showed a trapped lung, suggesting the pleural space could not fully re-expand.
• The authors' conclusion: The authors concluded that intrapleural hyaluronidase was effective in helping drain the fluid when standard techniques failed. They also concluded that unusual pleural fluid characteristics can be diagnostic clues in patients with cancer.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Lung Adenocarcinoma, Hyaluronic Acid, Pleural Mesothelioma, Cytology, Thyroid Transcription Factor-1 (TTF-1), Calretinin, Ber-EP4.

Related studies

• Role of HEG1 and Claudin-4 Immunohistochemistry in the Differential Diagnosis of Lung Adenocarcinoma from Malignant Mesothelioma in Pleural Effusion Cytology — A.E. Abdelrahman, F.A. Elbadry, et al. (2025)
• Differences in Pleural Fluid Amylase Levels in Patients with Malignant Pleural Effusion Based on Cancer Type, Histologic Type, and Epidermal Growth Factor Receptor Mutations — M. Shimoda, Y. Tanaka, et al. (2023)
• Diagnostic efficacy of electron microscopy and pleural effusion cytology for the distinction of pleural mesothelioma and lung adenocarcinoma — H. Domínguez-Malagón, A.M. Cano-Valdez, et al. (2016)
• Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology — V.Y. Jo, E.S. Cibas, et al. (2014)
• Cytological differential diagnosis among adenocarcinoma, epithelial mesothelioma, and reactive mesothelial cells in serous effusions by immunocytochemistry — X.Y. Su, G.D. Li, et al. (2011)
• The diagnostic utility of D2-40, calretinin, CK5/6, desmin and MOC-31 in the differentiation of mesothelioma from adenocarcinoma in pleural effusion cytology — T.S. Hyun, M. Barnes, et al. (2012)

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