It is unknown and given the wide variety of anecdotal and isolated evidence, I’m not sure it is one thing. A dermatologist in NYC has had a lot of success treating patients with a DMSA as he believes it is related to heavy metal toxicity.

Others have reported remission via cilantro, diet (grain free, dairy free, gluten free, etc.), etc. Other literature shows successful treatment with triple antibiotic ointment, anti-fungals, Accutane and other retinoids, etc.

Is it bacterial, viral, fungal, environmental, diet, who knows? The only thing that seems to be consistent is that it is inconsistent — what works for some will not work for others and the perceived root cause for some does not appear to apply to all. Personally, I think it is a symptom rather than a cause.

However, there are some who have been dedicated to finding a systemic answer for themselves who have had success. They may be dismissed as those who simply had Grover’s “resolve” on its own but, regardless, it appears to be something that can be addressed, given one’s tenacity.