Multifocal alveolar hyperplasia associated with lymphangioleiomyomatosis in tuberous sclerosis

Multifocal alveolar hyperplasia associated with pulmonary lymphangioleiomyomatosis is reported in a 21-year-old woman with tuberous sclerosis. Beside the cystic lesions of lymphangioleiomyomatosis, the tomography showed nodules up to 8 mm in both upper lobes. A proliferation of type II pneumonocytes and Clara cells lining the alveolar walls in an adenoma-like pattern was observed. Nuclear atypia, mitoses and necrosis were not observed, providing evidence against multicentric bronchioloalveolar carcinoma or micronodular atypical alveolar adenomatous hyperplasia. Whereas the lymphangioleiomyomatosis lesions showed strong positivity for HMB45 and expressed oestrogen and progesterone receptors, the alveolar hyperplasia was negative for these markers as it was for carcinoembryonic antigen, p53 and MIB1 antibodies. Multifocal alveolar hyperplasia in tuberous sclerosis is probably a benign hamartomatous lesion in our case without progression on a 2-year follow-up. Its histogenesis is unknown, but is possibly related to chromosome instability.