What condition is characterized by the penetration of the epidermis by curved hair, commonly seen in African Americans?

Pseudofolliculitis barbae is a condition that occurs when curly hair grows back into the skin after being shaved, leading to inflammation and the formation of small, painful bumps. This condition is particularly prevalent among individuals with naturally curly hair, such as many African Americans, due to the specific growth pattern of their hair which is more likely to curve back into the skin. When hair is shaved closely, the sharp edge can easily penetrate the skin, causing irritation and sometimes infection.

Understanding the context of this condition is important, as other conditions listed do not share this specific characteristic. Hidradenitis suppurativa involves inflamed sweat glands and is not related to hair growth patterns. Acne vulgaris primarily affects sebaceous glands and is accompanied by comedones and cysts, rather than being linked to ingrown hair. Epidermoid cysts are typically non-inflammatory cysts arising from hair follicles but do not involve the characteristic inflammation and skin penetration seen in pseudofolliculitis barbae.

Overall, pseudofolliculitis barbae is defined by its hallmark combination of curly hair re-entering the skin and the resultant irritation, making it the correct answer in this context.