Dissecting cellulitis (DSC) is a rare scarring hair loss condition. It is characterized by deep inflammation and leads to the formation of draining sinus tracts (especially tunnels that allow pus and inflammation to escape - see number 1 and 4 in the picture). The diagnosis of DSC in advanced stages is easy as these openings (sinus tracts) can be seen all over the scalp. In the early stages an up close exam and use of a dermatoscope can prove extremely helpful.
Early DSC is characterized on dermoscopy by large yellow dots, thin vellus hairs within the area, broken hairs and healing (covered) or open sinus tracts. The early stages of the nodule can mimic alopecia areata (see top right, number 3 and 5). A swiss cheese like appearance is common as scarring progresses (number 2). Biopsies of DSC often show deep inflammation but in more advanced cases show inflammation higher up in the skin which can easily be mistaken for another scarring alopecia known as "folliculitis decalvans." Therefore, it is not uncommon for patients to be referred with a diagnosis of biopsy "proven" folliculitis decalvans only to need to explain to them after examining their scalp that what they actually have is DSC.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299