Pulmonary Langerhans cell histiocytosis in adults: high-resolution CT-pathology comparisons and evolutional changes at CT.

OBJECTIVE: To compare high-resolution (HR) CT and histopathological findings and to evaluate serial CT findings in pulmonary Langerhans cell histiocytosis (PLCH).

METHODS: We reviewed CT of lung lesions in 27 adults (M:F = 20:7, mean age, 41 ± 12.3 years) with PLCH. After evaluating lung abnormalities including nodules, micronodules, thick-walled, thin-walled, and bizarre-shaped cysts and reticulation, observers compared CT findings obtained at lung biopsy sites with histopathological findings. The final CT was compared with the initial CT to determine disease extent changes.

RESULTS: The most frequently observed patterns of lung abnormalities were micronodules (n = 24, 89%), thick-walled (n = 22, 82%), and thin-walled (n = 22, 82%) cysts. Even thin-walled and bizarre cysts harboured active inflammatory Langerhans cell sheets and eosinophils in their walls. In thin-walled cysts, we noted pericystic inflammatory cell infiltrations along the alveolar walls, as well as pericystic emphysema. Thin-walled or bizarre cysts demonstrated a tendency to coalesce with surrounding cysts via their cystic wall destruction. Fourteen (52%) patients showed improvement and nine (33%) showed progressing disease.

CONCLUSION: More than half of patients with pulmonary PLCH show improvement at follow-up CT. Even thin-walled cysts harbour active inflammatory cells on histopathology and exhibit improvement at follow-up CT.