Are dissecting cellulitis and hidradenitis suppurativa different diseases?

Although dissecting cellulitis (DC) and hidradenitis suppurativa (HS) are classified separately, they share many clinical, dermatoscopic, pathogenetic, and histologic aspects, as well as therapeutic options. The association between DC, HS, and acne conglobata represents the follicular occlusion triad or follicular occlusion tetrad, which may include a pilonidal sinus. DC, also known as "folliculitis et perifolliculitis capitis abscendes et suffoidens," is classified as a secondary cicatricial and neutrophilic alopecia. It occurs with perifolliculitis of the scalp, dermal abscesses, sinus tract development, and secondary scarring alopecia. HS, sometimes known as acne inversa, is a chronic relapsing inflammatory disease afflicting apocrine gland-rich areas of the body with painful nodules and abscesses, sinus tracts, and scarring. Given the overlap between the clinical features and the pathogenesis of DC and HS, it would be more appropriate to consider these conditions as two different localizations of the same disease rather than two different pathologies, being a follicular occlusion disease occurring on the scalp and on the apocrine gland-rich areas of the body.