Study highlights challenges in diagnosing silica-linked diseases
Cases of 12 workers in Brazil show need for careful evaluation
Written by |
Careful evaluation is required to distinguish among sarcoidosis, silicosis, and silicosarcoidosis, three disorders that can cause similar patterns of lung problems in people exposed to silica, but that progress and respond to treatment differently.
A team of scientists in Brazil highlighted the challenges of distinguishing among the three conditions in a study describing the cases of 12 people exposed to silica on the job.
“Differentiating chronic silicosis, sarcoidosis, and silicosarcoidosis is clinically and radiologically challenging, yet essential for the appropriate management of silica-exposed individuals,” the researchers wrote in the study, “Silicosis, Sarcoidosis, and Silicosarcoidosis Are Overlapping Diagnoses and Difficult to Differentiate,” which was published in the American Journal of Industrial Medicine.
Silica is the most abundant mineral group in the Earth’s crust and the main component of sand. Workplace, or occupational, exposure to airborne silica dust is known to cause silicosis, a condition marked by progressive lung inflammation and scarring.
However, increasing evidence points to a link between silica exposure and other diseases, including sarcoidosis, a condition marked by granulomas, or abnormal clumps of inflammatory immune cells, that can form in the lungs and other organs.
Different diseases, different treatments
“While sarcoidosis is a [granuloma-related] disease and silicosis is characterized by [high-silica, scarred nodules], both conditions may present similar imaging findings; therefore, in many cases, differentiation relies on an integrated evaluation of high-resolution computed tomography (HRCT), occupational exposure history, and, in selected cases, [tissue analysis] confirmation,” the researchers wrote. “This distinction is clinically relevant because therapeutic strategies differ across these conditions.”
Sarcoidosis is generally treated with immunosuppressive medications to help limit disease activity. But these therapies offer little benefit for people with silicosis, and may in fact increase the risk of lung infections that could worsen the disease.
A 2025 study introduced the term silicosarcoidosis to describe patients who exhibit overlapping clinical, imaging, and tissue features of both silicosis and sarcoidosis.
The 12 workers in the study were diagnosed after assessing a combination of their silica exposure, results of clinical, imaging, and functional tests, and, if available, tissue analysis. Five people were diagnosed with sarcoidosis, four with silicosarcoidosis, and three with silicosis.
Patients in all three groups had been exposed to silica for a median of 11-12 years. The largest proportion of patients, about one third, reported working in marble. This was followed by construction work, reported by one quarter.
By analyzing data from the three patient groups, the researchers found certain imaging features that were often helpful for distinguishing sarcoidosis from silicosarcoidosis.
People with silicosis were more likely to have a specific pattern of inflammatory lung damage called centrilobular micronodularity and tended to have more hardened lymph nodes visible on scans. Centrilobular micronodularity is marked by tiny, scattered spots that show up in the center of the lung’s smallest air units on an imaging scan.
The team noted, however, that while these features can help differentiate among these diseases, it’s crucial for clinicians to conduct a thorough workup to arrive at a conclusive diagnosis.
“Our findings highlight the necessity of integrating occupational history with longitudinal clinical assessment, [lung] function testing, serial [lung imaging] evaluation, and, when available, bronchoscopy with [lung fluid collection] and tissue biopsy,” the team wrote. Bronchoscopy is a minimally invasive procedure used to visualize the airways.
While immunosuppressive treatments are known to work for sarcoidosis but not silicosis, there are no well-established guidelines for treating silicosarcoidosis. Follow-up data demonstrated that three of the four silicosarcoidosis patients showed improvements in lung imaging assessments after immunosuppressive treatments.
However, these imaging changes “did not consistently translate into symptomatic or functional gains,” the researchers wrote.
And because the study was limited to just a handful of patients, “any consideration of immunosuppressive therapy in silicosarcoidosis should be interpreted with caution and cannot be generalized, underscoring the need for larger … and multicenter studies before therapeutic strategies can be defined,” they added.
The team also highlighted that accurately identifying sarcoidosis, silicosis, and silicosarcoidosis is important not only for appropriately managing individual patients but also for informing public health interventions.
“In countries such as Brazil, where exposure to [breathed-in] … silica remains prevalent in mining, construction, and stone-processing industries, achieving greater diagnostic accuracy directly influences not only clinical management but also the implementation of primary and secondary prevention strategies,” the researchers wrote.
