S-LAM in a man: the first case report

Menstrual cycle variation of retroperitoneal lymphangioleiomyomas in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease affecting women, classically involving the lungs. However, extrapulmonary manifestations also occur, including renal angiomyolipomas, retroperitoneal lymphangioleiomyomas and extrathoracic lymphadenopathy. The lung disease is hormone-responsive, but no information exists regarding sex hormone responsiveness of abdominal LAM. Here, we report two women with LAM whose abdominal lymphangioleiomyomas increased in size with hormonal changes of the menstrual cycle. This is the first description of abdominal lymphangioleiomyomas exhibiting hormone responsiveness in LAM. We describe these cases and summarize the literature on abdominal LAM. Menstrual cycle variation should be taken into account when assessing response to therapy, both clinically and in research studies.

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease that mainly affects women, particularly at fertile age. It is sporadic or associated with tuberous sclerosis complex. It is characterised by an abnormal proliferation of immature smooth muscle cells (SMC), which grow aberrantly in the airway, parenchyma, lymphatics and pulmonary blood vessels and which can gradually lead to respiratory failure. It affects several systems, affecting the lymphatic ganglia and causing abdominal tumours. Given its very low prevalence, a difficult to establish early diagnosis, absence of curative treatment and the difficulty in obtaining information, places LAM under the heading of the so-called Rare Diseases. There is a growing interest in the study of this disease which has led to the setting up of patient registers and an exponential growth in LAM research, both at a clinical level and cellular level.

Mammalian target of rapamycin signaling and autophagy: roles in lymphangioleiomyomatosis therapy

The pace of progress in lymphangioleiomyomatosis (LAM) is remarkable. In the year 2000, TSC2 gene mutations were found in LAM cells; in 2001 the tuberous sclerosis complex (TSC) genes were discovered to regulate cell size in Drosophila via the kinase TOR (target of rapamycin); and in 2008 the results were published of a clinical trial of rapamycin, a specific inhibitor of TOR, in patients with TSC and LAM with renal angiomyolipomas. This interval of just 8 years between a genetic discovery for which the relevant signaling pathway was as yet unknown, to the initiation, completion, and publication of a clinical trial, is an almost unparalleled accomplishment in modern biomedical research. This robust foundation of basic, translational, and clinical research in TOR, TSC, and LAM is now poised to optimize and validate effective therapeutic strategies for LAM. An immediate challenge is to deduce the mechanisms underlying the partial response of renal angiomyolipomas to rapamycin, and thereby guide the design of combinatorial approaches. TOR complex 1 (TORC1), which is known to be active in LAM cells, is a key inhibitor of autophagy. One hypothesis, which will be explored here, is that low levels of autophagy in TSC2-null LAM cells limits their survival under conditions of bioenergetic stress. A corollary of this hypothesis is that rapamycin, by inducing autophagy, promotes the survival of LAM cells, while simultaneously arresting their growth. If this hypothesis proves to be correct, then combining TORC1 inhibition with autophagy inhibition may represent an effective clinical strategy for LAM.