Characteristics of multiple nodules in a patient with pulmonary Langerhans cell histiocytosis: A case report.

BACKGROUND: The common computed tomography findings of pulmonary Langerhans cell histiocytosis (PLCH) are multiple cysts and micronodules predominantly in middle to upper lung lobes. Non-cystic nodules and large nodules are atypical findings of PLCH.

CASE SUMMARY: The patient was a 48-year-old Japanese man with a smoking history (20 cigarettes/d, 28 years) and no symptoms. Multiple nodules existed in all lung lobes, predominantly in the right lower lobe. Some nodules seemed to be distributed randomly, and others were adjacent to bronchus. Most nodules were solid; some small ones were cystic. The largest nodule was 22 mm in diameter. Although metastatic lung tumors were suspected, thoracoscopic lung biopsy led to the diagnosis of PLCH. At 6 months after he quit smoking, all nodules had almost disappeared. We investigated the characteristics of nodules at diagnosis in detail. Of 349 nodules in total, 116 were in upper and 199 were in lower lobes. Ninety-six (27.5%) were cystic; the remaining 253 (72.5%) were non-cystic. The prevalence of cystic nodules was higher in upper lobes than in lower lobes (right upper 37.5% vs lower 18.2%, P = 0.0068; left upper 48.1% vs lower 24.4%, P = 0.0078). The average size (dia.) of cystic nodules was smaller than that of non-cystic nodules (5.03 mm vs 7.40 mm, respectively, P < 0.0001).

CONCLUSION: Although multiple non-cystic nodules including large nodules (over 20 mm) are atypical, PLCH should be included in differential diagnoses. The presence of small cystic nodules predominantly in upper lobes and asymptomatic situation are also important for differential diagnoses to distinguish from metastatic cancers.