To the Editors:
A 43-yr-old, nonsmoking female undergoing gynaecological surgery for menorrhagia was noted to have reduced arterial oxygen saturation and, on direct questioning, reported longstanding, mild, exercise-limiting dyspnoea. Treatment with inhaled bronchodilators had had no effect on her symptoms. Over the succeeding 2 yrs she developed progressive dyspnoea with corresponding deterioration in exercise tolerance. At that time, standard section computed tomography (CT) showed diffuse changes that were considered nonspecific, consisting of difficult-to-characterise opacities without zonal predominance; specifically, there were no conspicuous cysts. The features were suggestive of an infiltrative process and lung function assessment disclosed a forced expiratory volume in 1 s (FEV1) of 2.12 L (80% predicted), forced vital capacity (FVC) of 2.66 L (88% pred) and transfer factor of the lung for carbon monoxide (TL,CO) of 49% pred. A surgical lung biopsy was performed. Ultrasound of the kidneys disclosed no abnormality; specifically, there was no evidence of angiomyolipoma.
Lung histology showed an interstitial proliferation of cytologically bland, mainly rounded cells with predominantly clear cytoplasm (fig. 1a) and without obvious mitotic activity. In areas, these cells formed nodules in the alveolar parenchyma, while elsewhere, the proliferation was more diffuse. Focally, the cells showed a more spindled morphology, having blunt-ended nuclei and moderate volumes of eosinophilic cytoplasm (fig. 1b), a characteristic of lymphangioleiomyomatosis (LAM). All cells were positive for smooth muscle actin (SMA) and desmin, with focal positivity for HMB45. They were also positive for progesterone and oestrogen receptors. A periodic acid–Schiff stain for glycogen was focally positive. Following clinicopathological review, it was felt that the lack of imaging features characteristic of LAM, the lack of S-100 positivity characteristic of a …