I found an article in French that reports three cases of pediatric FFA, including 2 twin girls, aged 14, and a 7-year old.
In the discussion the authors believe that the twin girls case suggest a strong genetic causality for the condition and also point to facial papules, which they think are mostly present in pre-menopausal ladies.
You can find the main bullet points here:
http://www.sciencedirect.com/science/article/pii/S0151963814008394
the complete article is, unfortunately, unavailable unless paid for.