The Pathophysiology of the Lungs in Tuberous Sclerosis

Pulmonary involvement in tuberous sclerosis is rare. Among the small number of reported cases with involvement of the lungs, less than 50 per cent of the patients had epilepsy or mental retardation compared with the usual clinical picture of the disease (familial adenoma sebaceum and symptoms of central nervous system involvement). The other manifestations of tuberous sclerosis were present in the usual incidence. The onset of respiratory complaints occurred later in life, and pulmonary involvement was more common in females than males. The case reported here is typical in that the patient lacked part of the classic syndrome by not having epilepsy. Her protracted course was attributed partly to the absence of spontaneous pneumothoraces, but progression of the pulmonary disease led to cor pulmonale. The primary physiologic defects were “fixed” obstruction of the airways and the pulmonary vessels, with marked hyperinflation and severe ventilation-perfusion inequalities that produced hypoxemia at rest and wasted ventilation (dead space effect). The pulmonary diffusing capacity was only slightly decreased. This corresponded well to the histologic findings in the lung biopsy; the changes were patchy and proliferative in nature without scarring and destruction.