March 2026 Research Update

This month added an early, cautious signal that a urine marker may be different in people with LAM, but it is not ready for personal decision-making. In a small comparison study, one form of a protein called cathepsin K (pro-CatK) was higher in urine from people with LAM than in healthy volunteers, while another form (mature CatK) was not. The same study did not find strong links between this urine marker and how severe lung cysts or breathing test changes were, which suggests it may not be a simple stand-in for lung disease severity yet. [1]

One reason this work may matter is that LAM can affect more than the lungs, including bone health, and the urine marker showed a connection to that area. Higher urinary pro-CatK tracked with femur bone density scores in the LAM group, while a second urine test related to bone breakdown (NTX) did not show a clear difference between groups in this small sample. At the same time, pro-CatK did not clearly track with VEGF-D (a blood marker sometimes used in LAM), sirolimus use, or imaging-based cyst measures in this cohort. [1]

Separately, imaging data from people with tuberous sclerosis complex (TSC) reinforced the idea that LAM can be part of a broader, multi-organ picture for some patients, even though this was not a LAM-only study. In this group of 57 people with TSC, chest and abdominal CT scans found LAM in a subset of those who had extracranial imaging, alongside kidney and liver growths and other findings. The study also illustrated that different scan types can be better for different problems, rather than one scan being best for everything. [2]

For patients and caregivers, the main addition this month is a possible new urine marker (pro-CatK) that might someday help describe parts of LAM biology, including bone-related changes, but it is still early research. The study was small and did not show that this urine marker clearly reflects lung disease severity or treatment status, so it should be viewed as a lead that needs confirmation in larger groups. The TSC imaging study supports a practical point many families already experience: for people with TSC, different organs may need different types of imaging, and LAM may appear as one part of that wider set of findings. What remains uncertain is whether pro-CatK will prove useful for monitoring LAM over time, predicting outcomes, or guiding care. [1] [2]

This month reinforced that LAM does not always show up in a single, typical way, and diagnosis can depend on matching imaging findings with tissue testing and the person's broader history. Case-based reports described LAM presenting as a pelvic mass outside the lungs and, separately, as cystic lung disease with a collapsed lung (pneumothorax) in a man. Together, these reports underline that LAM may be considered even when the presentation is unusual, and that confirmation may require pathology tests that look for characteristic markers in tissue. [3] [4]

In the pelvic case, the lesion looked like a more common gynecologic problem on imaging, and the diagnosis was made after surgical removal and specialized staining of the tissue. The report described complete resolution on follow-up imaging at 6 months, with continued surveillance planned and no lung or kidney involvement found at that time. This helps illustrate that extrapulmonary (outside the lungs) LAM can mimic other conditions and may only become clear after a detailed pathology workup. [3]

In the male case, lung imaging showed thin-walled cysts and the person presented with pneumothorax, with the diagnosis supported by a history of a kidney angiomyolipoma and tissue findings positive for LAM-associated markers. The report's central point was not that LAM is common in men, but that it can occur and may be overlooked among other causes of cystic lung disease. For patients, this mainly adds awareness that diagnostic certainty often comes from combining scan patterns with other clues and, when needed, tissue confirmation. [4]

For patients and caregivers, these case reports mainly add understanding about diagnostic pathways rather than changing what is known about typical LAM. They show that LAM can appear outside the lungs and can also be diagnosed in a man, which may help explain why some people go through several steps before getting a clear answer. Because these are individual cases, they cannot tell how often these situations happen, or what the usual outcomes are. What they do clarify is that when LAM is not presenting in a classic way, imaging alone may not be enough, and tissue testing and the person's full medical history can be key pieces of the diagnosis story. [3] [4]

This month included a small clinic-based report where several people with LAM who took sirolimus described breathing improvement alongside better breathing test numbers, but the evidence remains preliminary. In this five-person series, some patients had increased FEV1 (a breathing test measure of how much air can be blown out in 1 second) and improvement in shortness of breath after starting sirolimus. Two patients in the same series declined treatment or further evaluation, which also reflects real-world variation in diagnosis and treatment decisions. [5]

The report also highlighted that LAM diagnosis in routine care can rely on a mix of approaches depending on the situation, including characteristic lung cysts on high-resolution CT and, in some cases, surgical lung tissue confirmation. Not every commonly discussed marker was available, as VEGF-D was mentioned but not reported for these cases. Because there was no comparison group and the numbers were small, the report cannot show how much improvement was due to treatment versus other factors, but it documents what was observed in this clinic's patients. [5]

For patients and caregivers, this report may be most useful as a real-world description of what follow-up can look like when sirolimus is used, including tracking symptoms and breathing tests over time. It adds to the broader picture that sirolimus is being used in routine practice and that improvements in breathing and breathing tests were observed in some individuals in this small series. At the same time, this kind of report cannot predict what will happen for any one person, and it does not answer questions like how often benefits occur or how it compares with other approaches. What remains uncertain from this month's evidence is how these observed changes would look in larger groups with longer follow-up and more standardized measurement. [5]