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Workers who build engineered stone countertops often present with atypical and advanced features of silicosis, which may be missed by physicians, delaying diagnosis and treatment, according to findings from a cross-sectional pilot study.

Among 21 workers who underwent preliminary analysis at a large urban safety-net hospital, 48% had atypical imaging features of silicosis, including diffuse nodularity, multiple cavitary lesions, ground-glass/mosaic attenuation, and crazy paving, reported Sundus Lateef, MD, a diagnostic radiology resident at the University of California Los Angeles, during the Radiological Society of North America annual meeting in Chicago.

Remarkably, silicosis was diagnosed in just four workers at initial encounter by primary clinicians and in seven workers by radiologists. All patients were symptomatic; dyspnea (91%) and cough (81%) were the most common symptoms.

Alternative diagnoses, including mycobacterial and atypical infections, were initially suggested in most cases, Lateef said.

"This is a new and emerging epidemic, and we must increase awareness of this disease process so we can avoid delays in diagnosis and treatment for our patients," she noted. "These new cases of silicosis demonstrate radiology findings different from the historical disease, and doctors may not be aware of the diagnosis when they see these images."

A resurgence of silicosis has been reported in engineered stone countertop workers in recent years, Lateef said. These countertops are made from quartz aggregate held together with a resin binder, and they contain substantially more crystalline silica than natural stone versions.

Silicosis is caused by the inhalation of crystalline silica dust produced in construction, coal mining, and other industries, the researchers noted. Workers who cut, shape, grind, and polish engineered stone countertops may be exposed to significant amounts of silica dust.

The prognosis for silicosis is poor, with gradually worsening lung function leading to respiratory failure. The disease also makes patients more vulnerable to infection in the lungs, chronic obstructive pulmonary disease, autoimmune disease, and lung cancer, Lateef noted.

Brent Little, MD, of the Mayo Clinic in Jacksonville, Florida, told MedPage Today that "any kind of stone working presents a risk of silicosis, so workers in this field should have high-efficiency masks, and they should wear those masks, and the buildings where this work is done should have sufficient ventilation and air filtration systems to reduce exposure to silica."

This study suggests that clinicians should understand the importance of a good patient history, which will give hints as to the possible cause of pulmonary complaints, he said. "Cough and dyspnea are features of many diseases, and silicosis is often misdiagnosed, and some of the masses observed on imaging can be misdiagnosed as lung cancers or other diseases."

"Stopping exposure to silica dust will halt the damage, but fibrosis scarring that has already occurred remains a scar," he added, noting that the risk of developing silicosis is exposure-dependent.

Lateef and colleagues said that research has shown that more than half of California workplaces exceed the maximum permissible exposure limit to silica dust during workplace inspections.

"There is a critical lack of recognition of exposure and screening for workers in the engineered stone manufacturing industry," Lateef said. "There needs to be a push for earlier screening and advocacy for this vulnerable population, which in our case were Spanish-speaking immigrant workers."

For the study, Lateef and colleagues included 21 workers with available CT findings and pulmonary function tests, all of whom were Hispanic men. Median age was 43, and median exposure was 18 years.

CT images were classified as typical or atypical for chronic silicosis defined as mediastinal lymphadenopathy and upper-lobe predominant small nodularity and/or progressive massive fibrosis.

Patients with consolidations (including large opacities >1 cm) had lower diffusing capacity of the lung for carbon monoxide than patients without large opacities (18.1 vs 24.5, P=0.02).

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