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Your skin condition is most likely Keratosis pilaris
with or without acne
. It is a familial skin condition which appears usually at upper thighs and upper arms but may be at back shoulder face and some times generalized.
You can use the following though treatment is not always required-
1. Capsule- Tetracycline
500mg (or doxycycline 100 mg / minocycline
100mg ) twice daily for 1-2 months orally.
cream or gel/ Adapelen cream or gel- you could apply twice daily on trunk and extremity and once at night on face for 1-2 months
3. Follow up needed after end of 1-2 months.