Hello Dr. Simple question. Is it possible to adquire ochronosis exogenous while using HQ 4% during 5-6 weeks? I used HQ 4%, combined with retin a and steroide to treat post inflammatory hyperpigmentation after a chemical peel 1 year ago. Use of mentioned productos was for 3 consecutive days, followed by 3 more days of non topical use. Total period, 5-6 weeks. Problem is that I still have a permanent darkening in periorbital and malar areas that does not respond to treatment and are refractory in 15 days after any cryotherapy o chemical procedure. Skin with minimal aplication (1-2 weeks) of the mentioned HQ, retin a and steriod compund is normal. Skin with more application of the same compound (5-6 weeks) remains brown-gray dark; and its been a year know since the application and no recovery is seen.