May 2026 Research Update

Studies this month pointed to two different ways diagnosis might become more precise in the future: patterns in exhaled breath chemicals and patterns seen in tissue staining. The clearest message is that these approaches can separate some lung diseases well, but LAM can be harder to distinguish and some commonly used tissue markers may be patchy in subtle samples. This helps explain why LAM diagnosis can sometimes require multiple pieces of information rather than one single test. [1] [2]

In a large breathomics study, researchers measured many breath volatile organic compounds (VOCs) and used machine learning to try to sort adults into asthma, COPD, cystic fibrosis, LAM, or healthy control groups. The model performed well across the whole set of diseases, but LAM had some of the weakest separation and sensitivity compared with other groups, meaning the breath pattern was harder for the model to correctly pick out as LAM. The study also mapped networks of VOCs, suggesting LAM may involve shifts in how breath chemicals relate to each other rather than a single standout chemical. [1]

In a tissue-based study, staining for TSC2 loss and cathepsin K was consistently strong across pulmonary and nodal LAM samples, including subtle lesions, while HMB-45 was often only focal and beta-catenin could be hard to interpret in subtle areas. In plain terms, this suggests some tissue markers may be more reliable than others when the LAM changes are small or hard to see. The study also included a related condition (micronodular pneumocyte hyperplasia), where TSC2 loss was also observed, showing that no single stain automatically answers every diagnostic question. [2]

For patients, this month adds clarity about why LAM diagnosis can be challenging and why different tests may give uneven answers. Breath-based testing is still early research, and in this report it was not yet strong at picking out LAM compared with other lung diseases, so it mainly helps researchers learn what signals are and are not distinct. The tissue staining results may matter sooner because they address real-world diagnostic uncertainty in small or subtle samples, but they still do not replace the need to interpret results in context with imaging and other findings. [1] [2]

This month's case reports emphasized that LAM does not always look the same from person to person, even with shared genetics, and it can appear alongside other lung conditions. They also highlighted that different measures of health can move in different directions over time, such as stable breathing tests but worsening exercise tolerance. These reports cannot predict what will happen for others, but they make the range of possible experiences more concrete. [3] [4]

In one person with diffuse cystic lung disease, doctors first found organizing pneumonia (a type of inflammatory lung process) and later confirmed LAM using transbronchial lung cryobiopsy, along with LAM-typical tissue staining and rising VEGF-D (a blood marker often used in LAM). The organizing pneumonia improved after corticosteroid treatment, while imaging showed the cyst burden increased over time, separating the short-term inflammatory problem from the underlying cystic disease process. The biopsy approach was reported as completed without complications in this single case. [4]

In a report of identical twins with tuberous sclerosis complex-associated LAM (TSC-LAM), both were treated with long-term sirolimus and followed for 10 years. Lung function measurements were described as generally stable during therapy, but their six-minute walk distance declined and their experiences differed in areas such as VEGF-D levels, timing of oxygen needs, weight changes, and menstrual irregularities. This shows that even when genetics and treatment are similar, day-to-day impact and physical capacity can still diverge. [3]

For patients and caregivers, these reports mainly add understanding rather than changing anything immediately. They illustrate two practical points: LAM can be confirmed only after careful testing when another lung condition is also present, and long-term follow-up can show different trajectories depending on whether you look at breathing tests, imaging, or exercise ability. The uncertainty is that these are 1-person and 2-person reports, so they cannot tell how common these patterns are, but they can help people recognize that variation is expected and that different health measures may not always move together. [4] [3]