Brief Answer:
Add an oral antifungal; rest can be continued
Detailed Answer:
Hello and welcome to healthcaremagic.
I am Dr. Kakkar. I have gone through your query and I have understood it.
Acne commonly involves face, trunk, chest and shouders (all these areas are rich in sebaceous glands). All these areas may or may not be involved simultaneously.
Trunk acne is more resistant and more prone to relapse then facial acne(persists longer).
Another possibility that could be the reason for back eruptions in your case is of pityrosporum folliculitis(caused by yeast) even though Pityrosporum folliculitis ITCHES a lot and is commonly seen in hot, humid weather conditions. Clinically both look the same except the itching part which is prominent in Pitryosporum folliculitis. Acne usually does'nt itch or they itch only slightly.
Pityrosporum Folliculitis is caused by proliferation of yeast, Malasezzia furfur. Exactly the same yeast has been implicated in the pathogenesis of dandruff/seborrheic
dermatitis. The yeast can travel down the hair length to the back and chest and cause Pityrosporum Folliculitis of the back. Therefore your doctor is absolutely right when he says that dandruff and Pityrosporum Folliculitis are related. The scalp and back are rich in oil glands, therefore providing an ideal environment for the yeast to feed upon.
You said that you are already using
Benzoyl Peroxide cream. If i were your treating doctor i would have advised you to continue with that.
In addition to that, I would advice that you be put on a course of
oral antibiotics like Doxycycline OR
Azithromycin for 4-6 weeks, since the lesions on back and trunk are inflammatory (Papules and pustules).
In my practice i also start my patients on oral retinoids (
Isotretinoin) if they present me similar to you. Oral retinoids are Sebostatic(decreases oil production), normalises keratinization, are anti-inflammatory and decreases proliferation/population of
Propionibacterium acnes as well as yeast(which feeds on your oil) in hair follicles.
In addition to all this, I would suggest an oral antifungal in your case e.g
itraconazole 200mg once daily for a week to kill the yeast rapidly. Topiacal antifungal alone are not at all effective in Pityrosporum Folliculitis and patients need to be treated with oral antifungals.
Topical antifungals can be used to prevent a relapse, rather.
I hope this answers your query.
regards