[Micronodular pneumocyte hyperplasia in pulmonary lymphangioleiomyomatosis and tuberous sclerosis].

An open lung biopsy was performed in a 28-year-old woman with tuberous sclerosis and with spontaneous pneumothorax and interstitial changes in the chest X-ray. Microscopically a micronodular pneumocyte hyperplasia in addition to a lymphangioleiomyomatosis was found. The micronodular pneumocyte hyperplasia is considered to be a very rare lesion. Only 27 well documented such cases have been recorded so far, 24 in women and 3 in men. The age of the patients ranged between 20 and 57 years, with an average of 36 years. The micronodular pneumocyte hyperplasia occurs mainly in patients with tuberous sclerosis (20 of 27 cases) and it is often combined with a lymphangioleiomyomatosis (19 cases). In the differential diagnosis the atypical adenomatous hyperplasia is to be considered in the first place. In contrast to it, the proliferating cells of the micronodular pneumocyte hyperplasia show no atypia. The differentiation from a papillary adenoma can be difficult in small biopsies.