Cream, ointments, and gels that contain Retinoids, which is a medicine derived from Vitamin A, is called topical retinoids. The commonly prescribed retinoids include Tretinoin, Adapalene, and Isotretinoin. Topical retinoids are used in the treatment of acne, acne scars, fine lines and wrinkles, melasma, and actinic keratoses.
Acanthosis Nigricans
This article discusses the causes and management of dirty non-cleanable darkness over the neck and underarms, known as acanthosis nigricans.

Sebaceous Hyperplasia - Causes, Symptoms, Diagnosis, and Treatment
Sebaceous hyperplasia occurs when more oil is secreted by the sebaceous glands, leading to skin-colored or yellowish bumps over the skin.