Scalp ridges
A 65-year-old man was referred to the Family Medicine Skin Care Clinic for a possible pilar cyst of the scalp. He had a 4-year history of intermittent swelling of lesions on his scalp. The lesions sometimes had malodorous purulent drainage. The patient had diabetes and, as a teen, had acne that required oral antibiotic prescriptions. He denied any current acne or draining sinuses of the axilla or groin. Physical exam revealed multiple raised ridges of the posterior scalp with one area of trace tenderness, erythema, and scabs.
What’s your diagnosis?
The gyrate or cerebriform pattern of inflammatory, often pus-filled, subcutaneous tracts of the scalp pointed to a diagnosis of dissecting cellulitis. This patient did not have the fluctuant tracts frequently seen in more active disease but did have the scarring and alopecia common with this disorder.
Dissecting cellulitis is similar to acne and hidradenitis suppurativa in that it starts with follicular plugging. This plugging leads to inflammation, dilation and rupture of the follicle, and purulent sinus tract formation. The sinus tracts of the scalp can be extensive. Dissecting cellulitis is most common in 18- to 40-year-olds and more common in Black individuals.1 When it occurs in conjunction with cystic acne and hidradenitis suppurativa, it is known as the follicular occlusion triad syndrome.
,While oral antibiotics are an option for the treatment of dissecting cellulitis, oral isotretinoin is the first-line approach. Tumor necrosis factor alfa inhibitors have also been used with success, according to case reports.1
Given that this patient had a small area of current inflammation, he was started on oral doxycycline 100 mg twice daily for 2 months. He was scheduled for a follow-up appointment in 3 months to reassess his progress and to explore treatment with isotretinoin if the condition worsened or did not improve.
Photo and text courtesy of Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.