Cat litter is a possible trigger for sarcoidosis

This case stresses: ‘‘if you are not aware of it, you will not

Obviously, she appeared to be ‘‘hypersensitive’’ not to the cats but to the cat litter

M. Drent* P.A. Wijnen, A.W. Bootsand A. Bast*

+*ILD Care Team, Depts of#Respiratory Medicine,

Clinical Chemistry, Maastricht University Medical Centre, and

+

Dept of Toxicology, University Maastricht, Maastricht, The Netherlands.

Sarcoidosis is characterised by cellular immune activity with

noncaseating granuloma formation in various organ systems

with a multifactorial cause. Many causative agents are con-

sidered to be involved in the pathogenesis [1–5]. Gene–

environment interactions offer the potential for strengthening

the evidence of causation between exposures and sarcoidosis. It

is important to identify every potential exposure to triggers in

order to avoid irreversible damage. Inorganic agents, including

silica, have been reported to initiate inflammation and granu-lomatous reactions .

It is well known that cats can cause

allergic reactions, but less is known about the association of

inflammation and cat litter. We propose that silica, the major

component of cat litter, might be such an agent.

We report a case

of biopsy-proven sarcoidosis with birefringent material, mainly

silica, within the lung biopsy specimen. The patient had no

relevant occupational history, but had cats and was extensively

exposed to silica-containing cat litter. Initially, the patient

improved after starting immunosuppressive drugs and termi-

nating contact with litter. However, she deteriorated twice after

autoprovocation (re-exposure) to cat litter. After changing the

silica-containing cat litter for litter without silica, her clinical

condition improved substantially. Obviously, she appeared to

be ‘‘hypersensitive’’ not to the cats but to the cat litter

cat litter and sarcoidosis or a ‘‘sarcoid-like’’ granulomatous

reaction. Obviously, this is important, as many people have cats

with litter boxes. Therefore, it was recommended not to get rid of

the cats but rather choose appropriate cat litter, without silica.

This case stresses: ‘‘if you are not aware of it, you will not

recognise it!’’