Treatments for Dissecting Cellulitis of the Scalp: A Systematic Review and Treatment Algorithm

This study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was preregistered on PROSPERO (CRD42022364109). This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors. On 1 October 2022, two independent reviewers (E.M. and C.J.) searched MEDLINE and EMBASE databases from inception to search date with the following terms: (“dissecting cellulitis” OR “perifolliculitis capitis abscedens” OR “dissecting folliculitis” OR “Hoffman disease”).

A total of 773 articles were identified and filtered to remove non-English language and non-human studies. Duplicate articles were excluded. Titles and abstracts were screened for relevance. Full text review was then manually performed on the remaining 218 articles by the two independent reviewers (E.M. and C.J.). Studies that contained outcome efficacy data for DCS treatments were considered eligible for inclusion. Reviews, conference abstracts, meta-analyses, commentaries, non-relevant articles, and articles with no full-text available were excluded. Any discrepancies were discussed to consensus with a third reviewer (J.L.H.). Reference lists of articles that met inclusion criteria were screened for additional relevant articles and 5 additional articles were identified.

Two reviewers (E.M. and C.J.) independently completed data extraction. Any discrepancies were discussed to consensus with a third reviewer (J.L.H.). For each article, the study design, country of study, patient characteristics, study intervention, efficacy outcomes, and safety outcomes were recorded. Articles were assessed for quality utilizing Cochrane risk of bias for prospective trials [5] and Newcastle–Ottawa Scale (NOS) for cohort studies [6].

The antibacterial and antiinflammatory effects of oral antibiotics may play a role in mitigating DCS symptoms (Table 2) [11]. The overall response rate to systemic antibiotic treatments across studies was 97.8% (91/93). Antibiotics that were utilized include doxycycline (n = 18), dapsone (n = 4), azithromycin (n = 3), ciprofloxacin and trimethoprim (n = 2 each), and lymecycline, oxytetracycline, rifampicin, clindamycin, terramycin, chloramphenicol, cephalexin and gentamicin (n = 1 each). Antibiotic combinations studied included clindamycin and rifampin (n = 7). Time to response to oral antibiotics, when reported, ranged from 6 days to 18 months. Seven patients who received doxycycline in a prospective trial had a good response to the intervention after 3 months, but none were cured of their disease [12]. A retrospective cohort study by Badaoui et al. described moderate improvement in 40 patients who received various systemic antibiotics; however, patients relapsed frequently after discontinuation of treatment [4]. Gamissans et al.’s retrospective cohort study described 14 patients, 6 of whom received doxycycline for 3 months, 4 patients on a regimen of rifampin and clindamycin for 3 months, and 4 patients on dapsone. Overall, complete recovery of alopecia was seen in 3 patients, and 11 exhibited a partial response. Four of the patients had gastrointestinal (GI) distress [8]. Melo et al.’s retrospective cohort study demonstrated improvement in nine out of ten patients on lymecycline 300 mg (mg) per day for 3 months [13].

Retinoids have antiinflammatory and antiproliferative effects, which may normalize the epithelium and decrease follicular occlusion [14]. Isotretinoin has been the most studied oral retinoid for DCS with an overall response rate of 91% (142/156); 25.4% (29/114) of patients treated with isotretinoin had concomitant acne. Isotretinoin dosing ranged from 0.3–1 mg/kg/day and reported duration of treatment ranged from 1–12 months. Isotretinoin led to a significant reduction of inflammatory activity in 90.3% of 72 adult patients in a large retrospective multicenter study [15]. Badaoui et al.’s retrospective cohort study described improvement with isotretinoin in 33 of 35 patients; however, patients relapsed frequently after discontinuation [4]. Lee et al.’s retrospective study also reported complete or partial response in 12 out of 16 patients who received isotretinoin for their DCS. Although there was no significant correlation between the isotretinoin dose and degree of response, the two patients who had recurrences had received lower cumulative doses [16]. Another retrospective cohort study described a partial or complete response in three out of four patients who received isotretinoin. One out of three patients with a reported response had a recurrence [8]. Adverse effects reported with isotretinoin across all studies included xerosis, dry eyes, erosive skin lesions, pruritus, epistaxis, and hyperlipidemia. There was one report of alitretinoin use in the literature. Significant improvement was noted in a 15-year-old male who received a dose of 10–20 mg/day for 5 months; however, erosive skin lesions developed when the dose was increased to 20 mg/day [17]. Finally, a patient who was prescribed acitretin 30 mg/day was lost to follow-up [4].

It has been posited that biologics may downregulate key inflammatory markers such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-12/23, which are associated with follicular occlusion disorders such as DCS [18, 19]. Biologics studied for treatment of DCS include adalimumab, infliximab, secukinumab, guselkumab, risankizumab, and tildrakizumab. Most (70%, 14/20) studies on biologics for DCS have been published in the last 5 years. HS was reported as a comorbidity in 41.2% (14/34) of patients. The majority of patients had previously failed treatment with oral antibiotics (82.4%, 28/34) and oral retinoids (58.8%, 20/34).

Adalimumab (ADA) was the most studied, and overall 94.1% (16/17) of patients exhibited a response to the immunomodulator. Most (83.3%, 10/12) of the studies were case reports/series. Dosing of ADA ranged from 40–80 mg every 1–2 weeks. A response rate of 85.7% (12/14) was observed for infliximab (IFX) treatment across two retrospective cohort studies and five case reports/series. The IFX dosing interval was 5 mg/kg every 4–8 weeks. Adverse events reported with IFX treatment include an infusion reaction, psoriasiform spongiotic dermatitis, and retrobulbar optic neuritis.

IL-23 inhibitors have a few reported cases in the literature for DCS. A reduction in pustules, decreased tenderness, and hair regrowth was observed in a 28-year-old male after receiving two doses of tildrakizumab [20]. Babalola et al. described improvement after 7 months in a 65-year-old male’s DCS symptoms with risankizumab dosed at 150 mg every 12 weeks [21]. Finally, guselkumab treatment at a maintenance dose of 100 mg every 8 weeks for 6 months was effective in inducing near complete resolution of symptoms in a case report of a male patient who had failed treatment with ADA [22].

Treatment with secukinumab, an IL-17 inhibitor, was described in a 63-year-old male patient. He had complete remission for 1 year after taking secukinumab 150 mg weekly for 6 weeks (patient mistakenly took an extra loading dose) then monthly for 2 months. Although the patient developed an eczematous reaction as an adverse event, this was successfully treated with topical therapy [23].

Long-term prednisone therapy was reported in one patient. Signs of active inflammation subsided within 4 months and full regrowth of scalp hair was observed after 1 year of treatment. The patient was maintained on 5 mg of prednisone every other day after 1 year of multiple tapered courses of treatment [24]. Finasteride 1 mg/day was also shown to be effective in two out of three treated patients [25].

Zinc is known to have antiinflammatory and antioxidant properties via inhibition of inflammatory mediators such as TNF-alpha [26]. A retrospective cohort study which included eight patients receiving zinc found that none of them exhibited a response [4]. The use of zinc for DCS was also described in two case reports, both of which reported positive results [27, 28]. One of the patients was in remission for 5 years and the other had well-controlled lesions for 1 year. Oral saireito, a Japanese herb, improved DCS disease course in two patients [29].

Surgical excisions with and without skin grafts were reported to induce improvement in 21 patients across one retrospective cohort study and 13 case reports/series; long-term remission was reported across multiple studies. Many of the patients undergoing surgery had failed medical management with oral antibiotics and/or oral retinoids (Table 3). Split-thickness skin grafts were most commonly used for reconstruction. Complications were uncommon in the literature. Baneu et al. reported a seroma at the skin graft donor site [30], and Dellon et al.’s case series described a skin graft infection in one patient [31].

Photodynamic therapy (PDT) inhibits follicular secretions, mitigates hyperkeratinization, reduces inflammation, and ablates tissues. PDT may also destroy persistent microbial biofilms, which can contribute to DCS symptoms [32]. The overall response rate to PDT with aminolaevulinic acid (ALA) across three prospective trials, one retrospective cohort study, and six case reports/series was 88.3% (83/94).

Wu et al.’s 2021 prospective trial demonstrated a novel technique in which a heated microneedle was used to puncture lesions. Thereafter, 5% ALA was applied followed by red-light PDT treatment. After four sessions, a total of 34 out of 42 patients reported improvement. Ten of the patients had relapsed within 1 year. Itching, burning, swelling, and thin crusts were noted as transient side effects [33]. Su et al. and He et al. described similar procedures in 3 and 6 patients, respectively [34, 35]. All patients had good results, but notably, Su et al. used isotretinoin as a concomitant treatment in all patients [34]. Adverse events reported with PDT include erythema, pain, itching, and swelling.

Lasers may selectively or non-selectively destroy hair follicles, thereby counteracting the progression of events that lead to follicular occlusion and rupture [36].

Long-pulsed neodymium-doped yttrium–aluminum–garnet (Nd:YAG) laser treatment sessions were effective in reducing drainage and tenderness in four males aged 25–40. A total of three to seven treatment sessions were conducted [37]. A long-pulsed ruby laser was used to perform laser hair removal in two males and one female. All patients had beneficial results, although one reported crusting and erosion with persistent hypopigmentation [38]. A case series reported improvement in two males after treatment with the erbium-doped (Er):YAG laser. One of the patients had good results after two treatment sessions and the other improved after 4 sessions [39].

Improvement was observed in a single case report of a 35-year-old male who received four treatments with 800-nm pulsed diode laser. Significant epilation was reported after 1 month and the disease was quiescent at the 6 month follow-up [40]. In Glass et al.’s 1989 case report, excision with a carbon dioxide laser led to complete clearance of disease after 6 weeks. No recurrence was observed after 4 months [41].

A total of four patients received radiation therapy consisting of electron beam radiation or combination electron and photon radiation; all patients had decreased drainage and nodule sizes after the culmination of treatment sessions. Mild scalp irritation, erythema, xeroderma, and pruritus were noted [42]. A 2016 study by Paul et al. reported substantial improvement in a 46-year-old male with brachytherapy to the occiput [43]. Of note, x-ray irradiation, no longer used in the present day for cutaneous conditions given its side effect profile, was performed in nine patients across three studies conducted in the 1950s and 1960s and resulted in disease improvement in all patients [44‐46].

Gamissans et al.’s retrospective cohort study included one patient who received intralesional steroid injections that resulted in partial recovery of disease, although discrete skin atrophy was noted as a side effect [8]. A 30-year-old female experienced improvement after two treatments with hydrocortisone injections into abscesses every 4–5 days. However, the patient relapsed after 6 months of no treatments [45].

Fibrosis and flattening of DCS lesions were observed in three patients who underwent intracavitary foam sclerotherapy. No complications were noted throughout the course of treatment [47].

A 44-year-old male self-devised a compression dressing consisting of gauze, an eye patch, and a headband worn under a cap. The affected lesion became smaller and flatter after 1 month and demonstrated terminal hair growth after 4 months [48].

A variety of combination treatment approaches have been reported for DCS (Table 4). All 17 patients across ten case reports/series improved with combination therapies for DCS. A total of 14 patients on combined medical therapies such as oral retinoids and oral antibiotics improved, with the exception of one who was lost to follow-up. Similarly, three studies described combined medical and procedural treatments in four patients. Of the three studies, two examined intralesional steroid injection use combined with various doses of isotretinoin [49, 50]. All three patients improved.