Pericardial Effusion Requiring Surgical Window in a Young Woman With Breast Cancer and Prior Immune Checkpoint Inhibitor Exposure

Q: What are the key findings of this study?

Pembrolizumab exposure was associated with delayed acute fibrinous pericarditis and a 1.8 cm pericardial effusion 42 weeks post-therapy, requiring a surgical pericardial window and corticosteroids.

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Acute fibrinous pericarditis and pericardial effusion following immune checkpoint inhibitor therapy for stage IIA triple-negative breast cancer (n=1). Intervention: Prior pembrolizumab exposure (managed with surgical subxiphoid pericardial window, partial pericardiectomy, ibuprofen, colchicine, and hydrocortisone). Primary outcome: Resolution of hemodynamic instability and pericardial effusion symptoms following surgical pericardial window and anti-inflammatory therapy.

Q: What does this research mean for the field?

Pembrolizumab exposure can lead to delayed acute fibrinous pericarditis and severe pericardial effusion requiring surgical pericardial window creation and corticosteroid therapy months after treatment cessation. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Jasmin Kaur Bhullar; Doris Takwe

doi:10.7759/cureus.119446

November 10, 2026CureusOpen Access

Pericardial Effusion Requiring Surgical Window in a Young Woman With Breast Cancer and Prior Immune Checkpoint Inhibitor Exposure

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Key result

Pembrolizumab linked to delayed acute fibrinous pericarditis requiring surgical drainage ~42 weeks post-therapy.

n=1

Why the study?

Immune checkpoint inhibitors are a treatment strategy in triple-negative breast cancer associated with immune-related adverse events that in rare cases involve the pericardium and cause a pericardial effusion.

Key Points

To describe a case of severe acute fibrinous pericarditis and pericardial effusion requiring surgical intervention in a patient previously exposed to the immune checkpoint inhibitor pembrolizumab.
Case report of a young woman with triple-negative breast cancer presenting with symptomatic pericardial effusion 42 weeks after completing pembrolizumab immunotherapy.
Diagnostic evaluation included computed tomography, echocardiography, extensive infectious workups, autoimmune serologies, and pericardial fluid and tissue biopsy.
Therapeutic interventions comprised urgent open subxiphoid pericardial window creation, partial pericardiectomy, continuous drainage with a 20 French chest tube, and anti-inflammatory therapy with ibuprofen, colchicine, and corticosteroids.
Imaging demonstrated a circumferential pericardial effusion measuring up to 1.8 cm, while biopsy and cytology confirmed acute fibrinous pericarditis with severe inflammation and no evidence of malignancy.
The patient experienced complete resolution of dyspnea and blood pressure improvement to 135/92 mmHg within three days of surgery and medical therapy.
Two weeks post-discharge, recurrent symptoms revealed a loculated pericardial effusion of less than 1 cm without cardiac tamponade, which improved with intravenous ketorolac and conservative care.

Study Design

Type

Case Report (n=1)

Multicenter

No

Structured PICO

P

Population

1 woman aged 36 years with stage IIA triple-negative breast cancer and prior pembrolizumab exposure (9 months prior) presenting with severe acute fibrinous pericarditis and a 1.8 cm circumferential pericardial effusion.

E

Exposure

Urgent open subxiphoid surgical pericardial window (4 x 8 cm) and partial pericardiectomy with 20 French chest tube drainage for 2 days, plus medical therapy with ibuprofen 800 mg three times daily, colchicine 0.6 mg twice daily, and intravenous stress-dose hydrocortisone 200 mg every 6 hours followed by a 5-day taper.

O

Outcome

Symptom resolution and hemodynamic improvement within 3 days of treatment initiation, with recurrence of chest pain and a small-to-moderate (<1 cm) loculated pericardial effusion within two weeks of discharge managed conservatively with intravenous ketorolac.patient reported

Limitations

Single case report design prevents establishing a definitive causal relationship between pembrolizumab and the delayed onset of pericarditis
Limited existing data on delayed cardiovascular immune-related adverse events
Single case report design precludes establishing a definitive causal relationship between pembrolizumab and the delayed onset of pericarditis.
Data on delayed cardiovascular immune-related adverse events remain limited.

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Implication

This case report demonstrates that pembrolizumab therapy can be associated with delayed, life-threatening acute fibrinous pericarditis and pericardial effusion up to nine months after treatment cessation, requiring surgical pericardial window creation and histopathologic evaluation to exclude malignancy and infection.

Abstract

Immune checkpoint inhibitors (ICIs) have emerged over the past decade as a novel treatment strategy in triple-negative breast cancer (TNBC).However, they are associated with immune-related adverse events (irAEs).In rare cases, these may involve the pericardium and cause a pericardial effusion.We report a case of acute fibrinous pericarditis presenting as a significant pericardial effusion requiring surgical pericardial window creation in a patient with prior exposure to the ICI pembrolizumab.This case report illustrates that ICI therapy is not only associated with pericarditis managed medically or with pericardiocentesis but also with pericardial window and pericardiectomy.It underscores how challenging it is to differentiate infectious, malignant, and autoimmune etiologies in complex oncologic patients.

Discussion

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Cite This Study

Bhullar et al. (2026) conducted a case report in Acute fibrinous pericarditis and pericardial effusion following immune checkpoint inhibitor therapy for stage IIA triple-negative breast cancer (n=1). Prior pembrolizumab exposure (managed with surgical subxiphoid pericardial window, partial pericardiectomy, ibuprofen, colchicine, and hydrocortisone) was evaluated on Resolution of hemodynamic instability and pericardial effusion symptoms following surgical pericardial window and anti-inflammatory therapy. Pembrolizumab exposure was associated with delayed acute fibrinous pericarditis and a 1.8 cm pericardial effusion 42 weeks post-therapy, requiring a surgical pericardial window and corticosteroids.

synapsesocial.com/papers/6af5cd33a40bbe8669e89c9d https://doi.org/10.7759/cureus.119446

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Pericardial Effusion Requiring Surgical Window in a Young Woman With Breast Cancer and Prior Immune Checkpoint Inhibitor Exposure

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Pericardial Effusion Requiring Surgical Window in a Young Woman With Breast Cancer and Prior Immune Checkpoint Inhibitor Exposure

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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