Dissecting cellulitis of the scalp (DCS) is a rare skin disease and understudied. The aim of the study was to collect the demographic, clinical features and laboratory tests of patients with DCS in a dermatology outpatient clinic. A cross-sectional study was conducted in a department of dermatology in Beijing. Patients whose diagnoses have included DCS were selected from July 2021 to December 2021. DCS patients were stratified according to whether they were follicular occlusion triad (FOT) or not. There were 169 patients with DCS included. All 169 patients were male, and the median patient age was 32 years. The most common comorbidities in this study were seborrheic dermatitis (10.65%). Over 1/3 of patients had elevated white blood cell (WBC) and neutrophil counts, and 12 of 18 patients had dyslipidemia. CD8+ T cell counts increased in 15 of 26 patients while CD4+ T/CD8+ T ratios were all normal. DCS mainly affects men in their thirties. More research about DCS is needed to clarify the clinical significance of laboratory tests.

BACKGROUND: Different therapies have been used for dissecting cellulitis of the scalp (DCS) with poor results. Topical 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) is effective for many inflammatory skin diseases.
OBJECTIVE: To evaluate the efficacy and safety of fire micro-needling plus 5% ALA-PDT on DCS.
METHODS: Forty-two male DCS patients were enrolled and treated by four sessions of fire micro-needling plus 5% ALA-PDT (occlusion time: 3 h, 100 mW/cm2 for 20-32 min, 633 ± 10 nm LED) with an interval of 1-2 weeks. The reduction of lesions was evaluated at each follow-up visit. The patients` symptoms were evaluated by Dermatology Life Quality Index (DLQI). All of the side effects were recorded.
RESULTS: Forty-one DCS patients finished the treatments and the marked effective rate (MER) reached 65.85%. Ten patients (24.39%) were cured and 17 patients (41.46%) achieved excellent improvement. The median of lesion numbers decreased significantly from 25 to 7 (p < 0.001) with DLQI from 13 to 2 (p < 0.001). Although all the ten cured patients had a relapse during the 12-month follow-up, 5/10 patients had a remission of more than 6 months. All the patients tolerated PDT well with mild adverse effects.
CONCLUSIONS: Fire micro-needling plus 5% ALA-PDT is effective for Chinese male DCS patients without the need to take systemic drugs.

BACKGROUND: Medicinal therapies such as systemic retinoids and antibiotics have shown efficacy in the treatment of dissecting cellulitis of the scalp (DCS), but refractory cases are common. 5-Aminolevulinic acid photodynamic therapy (ALA-PDT) has been successfully used in medicine-resistant cases in recent years.
METHODS: A total of 12 patients who received ALA-PDT in addition to formally failed medicinal therapies were interviewed by telephone regarding improvement of symptoms, satisfaction, and side effects.
RESULTS: Overall, 58.3 % patients achieved greater than 50 % improvement of at least one symptom, and 16.7 % had little improvement for any symptom. The proportion of patients who had greater than 50 % improvement for pain, pruritus, swelling and suppuration were 36.4 %, 66.7 %, 33.3 % and 58.3 % respectively. 41.7 % patients were either satisfied or very satisfied with the ALA-PDT. The side effects were mainly pain and crusting that were mostly mild and recovered quickly.
CONCLUSIONS: ALA-PDT was safe and partially effective in reducing DCS symptoms as an adjunct to systemic medicinal therapies.

BACKGROUND: Dissecting cellulitis of the scalp (DCS) is a rare and long-standing disease and its aetiopathogenesis remains unclear. Various therapeutic alternatives exist. We attempted to assess the efficacy of oral isotretinoin in a series of patients.
METHODS: Seven cases of DCS followed and treated by one of the authors at the Sabouraud Centre in the Saint-Louis Hospital between 2007 and 2013 were retrospectively studied and the efficacy of oral isotretinoin was evaluated.
RESULTS: The seven patients included were males aged between 22 and 39 years, with alopecic nodules on the occiput (two cases) or the top of the vertex (five cases). Most patients were given oral isotretinoin at a dosage of 0.75mg/kg/day for at least nine months. The outcome was satisfactory with complete healing of the lesions and good regrowth in all cases. Follow-up after recovery lasted between 16 and 42 months.
CONCLUSIONS: Based on published studies and the results of the present study, oral isotretinoin at a dose of 0.75mg/kg/day may be proposed as first-line treatment for DCS.