[Contribution of high resolution x-ray computed tomography to the diagnosis of pulmonary histiocytosis X. Apropos of 12 cases].

The authors studied the value of high resolution computed tomography in twelve patients with pulmonary histiocytosis X. The aim of this study was to define the CT signs. More or less thin-walled air-filled cysts were observed in all but one case, although the subsequent follow-up of this case revealed the development of such cysts 6 months later. Nodules were also present in all but two cases. They sometimes consisted of excavated nodules. Reticulations, "frosted glass" appearance and irregularities of interface--all signs of a classical interstitial syndrome--were observed less frequently. The lesions were always diffuse, cortical and medullary. The predominance for the upper lobes was only observed in 50% of cases. The case examined on 2 occasions during the course of the disease at an interval of 6 months suggested the progression of small solid nodules towards larger, excavated nodules, finally resulting in thin-walled cysts which may eventually coalesce to force a "lacework" appearance. The pathophysiology of this progression of the lesions and therefore of the pulmonary eosinophilic granuloma is discussed by the authors.