Multisystem Erdheim-Chester disease presenting with pericardial effusion confirmed by the effusion cytology specimen

Area of Science:

• Histiocytosis
• Oncology
• Pathology

Background:

• Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis.
• Characterized by CD68+, CD1a- foamy histiocytes infiltrating various organs.
• Clinical presentation is variable, ranging from asymptomatic to multi-organ involvement.

Observation:

• A 52-year-old female with a history of papillary thyroid carcinoma presented with recurrent pericardial effusion.
• Radiological findings raised suspicion for ECD.
• Cytological analysis of pericardial effusion confirmed ECD with CD68+, CD1a- histiocytes.

Findings:

• BRAF V600E mutation was identified in the lesional histiocytes.
• Treatment with vemurafenib, a BRAF inhibitor, was initiated.
• Two months of vemurafenib treatment led to disease control and regression of pericardial effusion.

Implications:

• This case highlights the diagnostic utility of effusion cytology in ECD.
• Demonstrates the efficacy of targeted BRAF inhibition in managing ECD.
• Suggests BRAF V600E mutation as a therapeutic target in ECD with pericardial effusion.