PULMONARY HISTIOCYTOSIS-X

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Abstract
Cases (78) of histologically verified pulmonary histiocytosis X (HX) were analyzed retrospectively. The patients, predominantly young adults, ranged from 1 to 69 yr of age and males outnumbered females by 4 to 1. Some patients were asymptomatic and were only discovered after routine chest radiography, whereas others presented with pneumothorax, dyspnea, cough, constitutional disturbance, or symptoms attributable to extrapulmonary HX lesions. Physical signs of lung disease were often lacking, but widespread reticular and micronodular radiographic opacities were present, most apparent in the midzones and bases but often sparing the costophrenic angles. Restrictive defects and low diffusion capacity were often found, the changes constabilized or improved. The remaining cases deteriorated with the appearance of radiographic honeycombing or bullous change and 1/2 of these patients died. Poor prognostic features included extremes of age, multiple pneumothoraces, multisystem generalized disease, prolonged constitutional disturbance, extensive initial pulmonary radiologic involvement with formation of cysts and a low CO diffusing capacity. No form of treatment affected the course of the disease. The lesions consisted of a focal interstitial infiltrate of characteristic HX cells, pigment-laden macrophages, lymphocytes, and eosinophils, centered on airways and pulmonary arteries and veins. Initially, the lesions were very cellular and mitotically active, but later became increasingly fibrotic, which resulted in stellate scars, emphysema, and bronchiolectasis. Ultrastructurally, pentalaminar X bodies were found in the HX cells, and it was possible to identify these structures in cells obtained by bronchial lavage, thus establishing the diagnosis without recourse to open lung biopsy. EM is considered an important diagnostic procedure in the confirmation of the disease.