Silence of the LAM.

We read with interest the article by WARTH et al. [1] on mediastinal angiomyolipoma and tuberous sclerosis. Apart from mediastinal angiomyolipoma, lymphangioleiomyomato-sis (LAM) can occur as part of the genetic condition tuberous sclerosis [2]. Since the first report by CORNOG and ETERLINE [3], LAM has been increasingly studied for the pathological processes involved in atypical smooth muscle LAM cell proliferation. However, it has been difficult to gain complete understanding of the natural history of LAM due to its rarity. LAM tends to progress slowly and ultimately leads to respiratory failure. Nevertheless, the clinical course of patients with LAM can vary, with 10 yr survival between 10–60% [2]. Some patients survive for 20 yrs following presentation [2]. LAM may remain silent until spontaneous pneumothorax occurs, which is the most frequently presenting symptom [4]. The indications for pleurodesis in this condition are not well established. In our experience, surgical pleurodesis is usually recommended for patients with recurrent or spontaneous bilateral pneumothoraces, but higher rates of recurrence can be expected for this group of patients [4]. In addition, pleural symphysis following surgical pleurodesis may make future lung transplantation impossible. Multiple diffuse blebs may be seen intraoperatively (fig. 1), alerting the clinician towards this condition. Classically, a computed tomography (CT) scan shows multiple thin-walled cysts distributed throughout both lungs, although unilateral lung involvement has been described [5]. A CT scan can also help to detect other unsuspecting pathology [6]. Pathological examination is required for confirmation of LAM, which can be obtained by transbronchial, percutaneous or surgical biopsy. We advocate video-assisted thoracic surgery biopsy with excision of any bleb and culprit lesion, particularly in the case of associated pneumothorax. The lung is char-acterised by cystic changes associated with proliferation of atypical smooth muscle cells (LAM cells), which can involve bronchioles, vessels and airspaces explaining, in part, the occurrence of pneumothorax, chylothorax and haemoptysis in these patients. (fig. 2) Positive HMB-45 immunostaining and the presence of oestrogen and progesterone receptors are also characteristics of LAM. Despite reports of various therapeutic regimens, none offer a consistently effective response. Corticosteroids and cytotoxic agents usually provide little benefit. Medical hormonal therapy (progesterone, tamoxifen, luteinising hormone-releasing hormone agonist) and surgical hormonal therapy (oophorectomy, ovarian radiofrequency ablation) have been used with variable responses [7]. For end-stage lymphangioleiomyomatosis, lung transplanta-tion can be an effective treatment option, but recurrences in the transplanted lung may occur following lymphangioleiomyo-matosis cell migration [7]. STATEMENT OF INTEREST …