Question: I recently moved my practice to New Mexico. I keep getting lung biopsy results which say "foreign polarizable material and noncaseating granulomas." I'm unfamiliar with this nomenclature and haven't been able to contact the pathologist. Is this finding known by another name? All cultures and serologies are negative. Any thoughts on what I should do about these patients?

Answer: "Foreign polarizable material" is a descriptive term that further characterizes the nature of noncaseating granulomas on tissue biopsies. It refers to the presence of birefringent material revealed by polarizing microscopy at sites of granuloma formation. It should alert clinicians to the possibility of inhaled or circulating foreign substances such as talc, mica, aluminum, calcium, beryllium, etc that may provide a clue to the diagnosis. Endogenous material (calcium silicate or carbonate) may also polarize and not represent true "foreign material." It is sometimes possible to identify the polarizing material, particularly if it is abundant. Electron probe microanalysis can be used for this purpose.

Diagnosis of sarcoidosis by biopsy is a diagnosis of exclusion. Some feel that the presence of foreign bodies discovered by polarizing microscopy excludes the diagnosis of sarcoidosis. Yet other authors believe that the foreign material may be the allergen that stimulated the development of sarcoidosis in patients with this predisposition.

A patient with the finding of foreign body noncaseating granulomas should have a thorough history taken for occupational, recreational, or inhalational exposures; nasal insufflation of oils or topical substances; and for use of illicit drugs (cocaine). GERD with aspiration should also be excluded. If these are negative, a diagnosis of sarcoidosis should not be excluded, especially if other findings support it. A discussion with your pathologist will be helpful in reaching a final diagnosis.