Brocq provided early, comprehensive descriptions of numerous skin disorders, including keratosis pilaris, parapsoriasis and a form of dermatitis called "Duhring-Brocq disease" (named with Louis Adolphus Duhring and sometimes referred to as dermatitis herpetiformis).

Other eponymous skin diseases named after him are "Brocq's pseudopelade", a condition involving progressive scarring of the scalp, and "Brocq-Pautrier angiolupoid", a specific type of sarcoidosis of the skin named in conjunction with Dr. Lucien-Marie Pautrier (1876–1959).

With Pautrier he also described "Brocq-Pautrier syndrome" (glossitis rhombica mediana), characterized by rhomboid and shiny lesions on the midline of base of the tongue.

[3][4] Brocq is also credited for developing a tar solution used for the treatment of psoriasis.

Along with Ernest Besnier and Lucien Jacquet, he published a four volume encyclopedia of dermatology, titled "La pratique dermatologigue" (1900–04).