Isolated pulmonary involvement in Erdheim-Chester disease

Area of Science:

• Pulmonology
• Oncology
• Pathology

Background:

• Erdheim-Chester disease is a rare non-Langerhans cell histiocytic disorder, typically affecting long bones.
• Pulmonary involvement occurs in about half of systemic cases, but isolated lung involvement is exceptionally rare.
• Current treatment recommendations for isolated pulmonary Erdheim-Chester disease are not well-established.

Observation:

• A 52-year-old male presented with a spiculated lung nodule.
• Initial investigations including pulmonary function testing, bronchoscopy, and PET-CT showed a nodule with mediastinal/hilar adenopathy but no bone involvement.
• Diagnostic procedures were inconclusive, necessitating a wedge resection.

Findings:

• Histopathology and immunohistochemistry of the resected nodule revealed a fibrohistiocytic infiltrate.
• The infiltrate was positive for CD68 and negative for CD1A, S100, and BRAF V600E mutation, consistent with Erdheim-Chester disease.
• Brain MRI excluded central nervous system involvement.

Implications:

• This case underscores the diagnostic challenges posed by rare conditions like Erdheim-Chester disease presenting with isolated pulmonary involvement.
• Accurate diagnosis relies on a combination of advanced imaging, histopathology, and immunohistochemistry.
• Further research is needed to establish clear diagnostic and therapeutic guidelines for this rare presentation.