Presentation of pulmonary Langerhans cell histiocytosis before the development of lung cysts.

Pulmonary Langerhans cell histiocytosis (PLCH) affects mainly young, predominantly smoking adults with a peak at 20-40 years of age. Patients with PLCH often present with a nonproductive cough and/or dyspnea. High-resolution CT (HRCT) is the most important diagnostic modality in PLCH. The typical HRCT pattern combines small poorly limited nodules, cavitated nodules, and finally thick- and thin-walled cysts. In rare cases, HRCT enables PLCH to be diagnosed prior to the development of cysts.

Introduction

Cystic lung diseases are rare entities but one of the most common of these disorders is pulmonary Langerhans cell histiocytosis (PLCH). High-resolution CT (HRCT) scan is the most important diagnostic modality in PLCH. We present a case of PLCH indentified on HRCT and diagnosed on lung histology, prior to the development of cysts.

Case Report

A 66-year-old male patient was referred for the assessment of multiple and bilateral pulmonary nodules (Fig. 1), an incidental finding in a current smoking subject. He had no respiratory symptoms. Pulmonary function tests showed mild obstructive ventilatory defect and decreased diffusing capacity of the lung for carbon monoxide. Immunological, allergological, and serological testing was negative, as well as cytological and microbiological evaluation of bronchoscopic specimens. Histology of surgical lung biopsy revealed destruction of bronchiole walls and a nodular peribronchiolar infiltrate by sheets of Langerhans cells, indicated by strong positive staining with CD1a, thus confirming the diagnosis of PLCH (Fig. 2).

Figure 1

Pulmonary nodules in high-resolution CT scan.

Figure 2

Langerhans cells with a strong positive staining with CD1a.

Discussion

Cystic lung diseases are rare entities characterized by multiple intrapulmonary cysts. The most common of these rare disorders are PLCH and lymphangioleiomyomatosis. Less common causes include Pneumocystis jiroveci pneumonia, Birt–Hogg–Dubé syndrome, lymphocytic interstitial pneumonia, and amyloidosis [1, 2]. HRCT is the most important diagnostic modality in PLCH [3], suggesting the diagnosis and displaying different stages of disease. The typical HRCT pattern combines small poorly limited nodules, cavitated nodules (both of which may resolve), and finally thick- and thin-walled cysts; the last being the predominant finding as the disease evolves [1]. The HRCT pattern in this case demonstrated small airway inflammation but no cysts. Despite the patient's age, he was diagnosed at a very early stage of this disease, when he had micronodules (representing a destructive bronchiolitis), without cavitation or the development of cysts.