October 2022
Exposure to silica dust is one of the oldest known causes of pulmonary diseases, and is associated with a variety of occupations, such as construction, quarrying, and chemical industries.
While the inhalation of fine silica particles is a well-recognized risk factor for silicosis, several studies have reported an association between silica exposure and sarcoidosis or sarcoid-like granulomatous lung diseases.
According to the literature, silica exposure may also be a trigger for other conditions, including hypersensitivity pneumonitis (HP), lung cancer, tuberculosis, chronic obstructive pulmonary disease, and kidney disease.
A 44-year-old woman was admitted to hospital with end-stage renal failure, productive cough, and decreased exercise tolerance. She had owned nine cats, which resulted in long-term exposure (18 years) to silica-containing bentonite cat litter.
X-ray photoelectron spectroscopy revealed the presence of silicon in the lung biopsy specimen, as well as in the patient’s cat litter.
The pulmonary condition was suggestive of sarcoid-like lung disease, rather than silicosis, sarcoidosis, or hypersensitivity pneumonitis, according to the clinicopathological findings.
Renal failure appeared to be a result of chronic hypercalcemia due to extrarenal calcitriol overproduction in activated alveolar macrophages.
Ultimately, the patient was diagnosed with sarcoid-like lung disease complicated by end-stage renal failure from exposure to bentonite cat litter.
We believe that our patient’s disease was a result of the chronic inhalation of bentonite dust, as we excluded other possible causes and observed a significant improvement after the causative agent had been removed.