INTRODUCTION — Dissecting cellulitis of the scalp (DCS), also known as perifolliculitis capitis abscedens et suffodiens or Hoffman disease, is a chronic inflammatory disorder of the scalp characterized by boggy, suppurative nodules that are often associated with patchy hair loss (picture 1A-E). Follicular occlusion may be a key pathogenic event in the development of DCS. DCS may occur in association with other follicular occlusive disorders such as acne conglobata, hidradenitis suppurativa, and pilonidal cysts [1].
Data on treatment options for DCS are limited. Oral antibiotics and oral isotretinoin are the most commonly used treatments.
The clinical features, diagnosis, and management of DCS will be reviewed here. An overview of the characteristics and diagnosis of hair loss is provided separately. (See "Evaluation and diagnosis of hair loss".)
CLASSIFICATION — DCS is a type of primary cicatricial (scarring) alopecia, a group of inflammatory disorders that target hair follicles and result in follicular destruction and permanent hair loss. A classification scheme proposed by the participants of a 2001 workshop on cicatricial alopecia sponsored by the North American Hair Research Society further classified DCS as a neutrophilic form of primary cicatricial alopecia based upon pathologic features [2]. (See "Evaluation and diagnosis of hair loss", section on 'Classification' and 'Histopathology' below.)
EPIDEMIOLOGY — DCS most commonly occurs in Black males aged 20 to 40 years. However, DCS has also been reported in White persons [3,4] and those of other racial or ethnic groups [1,5-9], as well as in females [10,11] and adolescents [12].
PATHOGENESIS — The etiology of DCS is unknown. A defect in follicular keratinization leading to obstruction of the follicle is suspected to contribute to the development of DCS. This theory is supported by the observation that DCS occurs in association with other disorders of follicular occlusion. (See 'Associated disorders' below.)
Proposed pathogenic events in DCS are as follows:
●Sebaceous and keratinous material accumulates within dilated hair follicles
●Release of this material into the dermis triggers an intense neutrophilic inflammatory reaction followed by abscess and sinus tract formation
●Secondary bacterial infection can occur, leading to exacerbation of the disease
CLINICAL FEATURES — DCS usually manifests as boggy, suppurative nodules on the vertex and posterior scalp (picture 1A-E); however, other sections of the scalp can be affected. Drainage of pus or blood from involved skin is common. Because interconnecting sinuses are often present between nodules, the application of pressure to a nodule can result in drainage from a distant site. Patients often use head scarves, hats, or gauze dressings to hide these clinical manifestations.
Exudate from nodules of DCS is usually sterile; however, secondary infection can occur. Staphylococcus aureus [13], Pseudomonas aeruginosa [10], and anaerobic bacteria [14] have been isolated from sites of DCS.
Hair loss in DCS is usually patchy and most prominent on the skin overlying nodules. Although hair loss can be reversible in early stages of disease, scarring alopecia can develop in persistent cases [15].
The clinical course of DCS is chronic. Patients frequently experience periodic flares of varying severity, depending on the degree of inflammation. Pain or pruritus may be present [7,16]. Hypertrophic or keloidal scarring may occur (picture 2).
ASSOCIATED DISORDERS — DCS is considered a component of the follicular occlusion tetrad, a group of four disorders (hidradenitis suppurativa, acne conglobata, DCS, and pilonidal sinus) thought to have follicular occlusion as a key pathogenic event. Patients with DCS may exhibit other disorders in the follicular occlusion tetrad. Additional disorders, such as marginal keratitis [17], arthritis, spondyloarthropathy, keratitis-ichthyosis-deafness (KID) syndrome [18], and sternoclavicular hyperostosis, also have occurred in patients with DCS [1,19-21]. (See "Hidradenitis suppurativa: Pathogenesis, clinical features, and diagnosis" and "Pilonidal disease" and "SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome" and "Pathogenesis, clinical manifestations, and diagnosis of acne vulgaris", section on 'Acne conglobata'.)
HISTOPATHOLOGY — Histopathologic features of DCS vary according to stage of the disease and severity. Characteristic histologic findings of DCS are dense, predominantly neutrophilic, mixed-cell perifollicular infiltrates in the dermis. There may be abscesses in the dermis or subcutaneous tissue [1]. Follicular dilatation may be evident in early disease [15,22]. Granulomatous inflammation, scarring, and fibrosis are common in advanced or late-stage disease [23].
DIAGNOSIS — The diagnosis of DCS can usually be made clinically, although a culture should be performed to rule out secondary infection, and a biopsy may be necessary to confirm the diagnosis and rule out other forms of cicatricial alopecia if overlapping features are observed. In general, the diagnosis should be suspected in patients with a chronic, relapsing eruption characterized by multiple boggy, suppurative nodules on the scalp (see 'Clinical features' above). Adult men of African ancestry represent the most common patient population.
History and physical examination — The patient history should include an assessment of the duration of hair loss and associated symptoms. Patients with DCS typically complain of chronic and recurrent scalp nodules associated with purulent or bloody drainage. Given the association of DCS with other disorders in the follicular occlusion tetrad, patients also should be asked about a history of signs or symptoms of hidradenitis suppurativa, acne conglobata, or pilonidal cysts. Performance of a full skin examination is helpful for identifying patients with these diseases. (See "Hidradenitis suppurativa: Pathogenesis, clinical features, and diagnosis", section on 'Clinical manifestations' and "Pilonidal disease" and "Pathogenesis, clinical manifestations, and diagnosis of acne vulgaris", section on 'Acne conglobata'.)
The physical examination of the hair and scalp should include an assessment of the distribution and extent of involvement. Boggy nodules, typically 1 to 3 cm in diameter, involving the posterior and vertex scalp are typical of DCS. Palpation of the scalp aids in the detection of the classic boggy texture. Drainage of pus or blood and patches of alopecia overlying nodules are common findings.
The physical examination may also help to assess for the likelihood of hair regrowth. A loss of follicular orifices suggests permanent, scarring alopecia. General principles for the clinical evaluation of patients with hair loss are reviewed separately. (See "Evaluation and diagnosis of hair loss".)
Dermoscopy — Dermoscopy may be a useful adjunctive procedure in the clinical assessment of patients with DCS. (See "Overview of dermoscopy of the hair and scalp".)
Common findings are as follows [24]:
●Early disease – Empty follicular openings, yellow dots, and black dots
●Advanced disease – Yellow structureless areas and three-dimensional yellow dots imposed over dystrophic hair shafts
●End-stage disease – Confluent ivory-white areas without follicular openings
Biopsy — If the diagnosis of DCS is uncertain, a scalp biopsy should be performed to confirm the diagnosis and differentiate DCS from other cicatricial alopecias. A 4 mm punch biopsy is usually adequate. The recommended site for a biopsy is within a boggy, suppurative, or tender nodule; the goal is to sample a clinically active (ie, inflamed) lesion. Classically, histologic examination of DCS reveals a perifollicular neutrophil-predominant, mixed-cell inflammatory infiltrate. (See 'Histopathology' above.)
Some dermatopathologists prefer to receive two scalp biopsy specimens to allow for examination of the tissue in both vertical and horizontal sections. However, a single biopsy can be sufficient.
Culture — A bacterial culture should be performed to rule out bacterial infection. However, in most cases, exudate associated with DCS is sterile.
DIFFERENTIAL DIAGNOSIS — The differential diagnosis of DCS includes other inflammatory or nodular disorders that affect the scalp:
●Folliculitis decalvans – Folliculitis decalvans is an uncommon type of cicatricial alopecia that presents with multiple pustules and areas of scarring of the scalp. On examination, yellowish crusts or collarettes of scale at sites of ruptured pustules and tufted folliculitis (multiple hairs emerging from a single inflamed follicular orifice) are common findings (picture 3). The deep-seated nodules characteristic of DCS are not a typical feature of folliculitis decalvans. (See "Folliculitis decalvans".)
●Acne keloidalis – Acne keloidalis is a form of cicatricial alopecia that most commonly presents with multiple fibrotic or keloid-like follicular papules on the posterior scalp (picture 4A-B). Patients with advanced disease may develop keloid-like plaques or nodules. Although scarring and keloids may occur as a consequence of DCS, fibrotic, keloid-like papules or plaques are not the primary clinical feature in DCS. (See "Acne keloidalis nuchae: Pathogenesis, clinical manifestations, and diagnosis".)
●Bacterial folliculitis – Bacterial folliculitis is characterized by inflamed follicular papules or pustules (picture 5). Unlike DCS, large boggy nodules or abscesses are not typical features of folliculitis. (See "Infectious folliculitis", section on 'Bacterial folliculitis'.)
●Pilar cysts – Pilar cysts present as solitary or multiple firm, slow-growing subcutaneous nodules on the scalp (picture 6). Occasionally, a pilar cyst may become inflamed or infected. The presence of multiple nodules that are boggy or suppurative helps to distinguish DCS from pilar cysts. (See "Overview of benign lesions of the skin", section on 'Pilar (trichilemmal) cysts'.)
●Kerion – Kerion is a severe manifestation of tinea capitis that results from an intense immune response to the infection. Patients develop an inflammatory plaque with pustules, crusting, or drainage (picture 7). Unlike DCS, kerion is most common in children. However, kerion mimicking DCS has been reported in adults and children [6,25,26]. (See "Tinea capitis", section on 'Clinical manifestations'.)
TREATMENT — Treatment of DCS is warranted given the chronic and progressive nature of the disease and the high likelihood for scarring and permanent alopecia.
Overview — The key treatment strategies for DCS are to reduce inflammation, reduce follicular occlusion, and prevent and treat secondary infection. Multiple interventions have been used to achieve these goals; however, the ideal approach to treatment is unclear. Data on treatments are primarily limited to case reports and small series with limited follow-up, precluding conclusions on the relative efficacy of treatments. Our approach to the treatment of DCS is reviewed here. Other approaches may be reasonable.
Oral antibiotic therapy may have beneficial antiinflammatory and antibacterial effects and is our preferred first-line treatment for patients with mild to moderate DCS, given the favorable risk-to-benefit ratio. Tetracyclines, such as doxycycline, are commonly given. Oral isotretinoin, a drug that targets follicular occlusion, is our preferred initial treatment for patients with severe DCS and preferred next-line treatment for patients with milder disease who do not respond well to oral antibiotics. Treatment with oral antibiotics or isotretinoin is often discontinued during periods of remission to minimize the duration of drug therapy. However, there is a high risk of relapse after treatment.
Occasionally, patients present with very painful or fluctuant nodules for which an immediate intervention is necessary for symptom relief. Adjunctive therapies, such as intralesional corticosteroid injection and incision and drainage are useful in this setting. However, these interventions do not alter the course of DCS and should not be used as primary treatments.
Limited data suggest that other medical interventions may be of benefit for DCS. Examples include oral zinc and biologic tumor necrosis factor (TNF) inhibitors. Procedural therapies, such as laser hair removal, carbon dioxide laser ablation, and surgical excision, may also be useful in inducing longer-term remissions.
First-line therapy — The severity of disease influences our selection of initial treatment. While a severity scale for DCS is lacking, clinical severity can be assessed based upon a number of factors, including the number and size of lesions (eg, few to several or numerous), the amount of drainage (eg, slight or copious), and the extent of scarring (eg, localized or extensive).
Because secondary infection of DCS is possible, a bacterial culture should be performed prior to initiating treatment. If the culture identifies pathogenic bacteria, an antibiotic should be selected accordingly to treat the infection. The patient can then be transitioned to treatment directed at the underlying disease. (See 'Mild to moderate disease' below and 'Severe disease' below.)
Mild to moderate disease — Antibiotics (especially tetracyclines) are our preferred initial treatment for mild to moderate disease.
Oral antibiotics — Tetracycline derivatives, most notably doxycycline and minocycline, are widely used in the treatment of DCS. However, clinical trials evaluating antibiotic therapy are lacking and evidence is limited. In a retrospective study of 21 patients with DCS, four of five patients treated with doxycycline (mean daily dose of 100 mg per day) had a great reduction in disease activity [7].
We frequently initiate treatment with doxycycline 100 mg twice daily for a period of three months. If marked improvement is achieved after three months and maintained for another three months, we discontinue doxycycline. If a partial but insufficient response occurs after three months, we often switch from doxycycline to minocycline for another three months. In our experience, some patients who have inadequate responses to doxycycline exhibit greater improvement with minocycline. Alternatively, the patient can be treated with an alternative antibiotic (eg, azithromycin [7], ciprofloxacin [5,27,28] or rifampin with clindamycin [1,7]) or transition to oral isotretinoin therapy. Benefit of dapsone is suggested by a case report in which combination treatment with dapsone and isotretinoin was associated with clinical improvement after failure of isotretinoin monotherapy [29].
Potential adverse reactions to tetracyclines include gastrointestinal symptoms (nausea, abdominal pain or discomfort) and photosensitivity (particularly tetracycline and doxycycline). In addition, minocycline may cause dose-dependent vestibular effects, bluish skin dyspigmentation (usually following several months of therapy), pseudotumor cerebri, lupus-like drug reactions, or drug reactions with eosinophilia and systemic symptoms (DRESS). (See "Drug reaction with eosinophilia and systemic symptoms (DRESS)".)
Severe disease — Oral isotretinoin is considered the treatment of choice for severe DCS. Oral isotretinoin is also our choice for second-line treatment for patients with milder disease who do not respond well to oral antibiotics. This drug is generally reserved for these patients because of safety concerns and monitoring requirements. (See "Oral isotretinoin therapy for acne vulgaris".)
Oral isotretinoin — Support for the efficacy of isotretinoin for DCS stems from case reports and case series [3,7,16,30-35]. In a retrospective study of 51 patients with DCS, 33 of 35 patients treated with isotretinoin (0.5 to 0.8 mg/kg per day) experienced complete remission after three months [16]. However, relapses were common after treatment. A retrospective, multicenter study involving 72 patients with DCS treated with isotretinoin at an average dose of 0.25 to 0.5 mg/kg until a cumulative dose of 120 to 150 mg/kg demonstrated reduced inflammatory signs in 90 percent of patients [36]. In a case series of four patients, treatment of DCS with oral isotretinoin 0.5 mg/kg per day for up to four months after a four-month course of rifampin (300 mg twice daily) led to remissions lasting for up to one year [31]. In a retrospective study, seven of eight patients treated with isotretinoin (mean daily dose of 30 mg) had a significant reduction in inflammatory activity.
The recommended dose range is 0.5 to 1 mg/kg. Remission often occurs within three months in patients who respond to treatment [16]. Clinical experience suggests that treatment duration should be continued for at least four months after resolution or marked reduction of clinically active lesions. Relapse several weeks to months after discontinuation of isotretinoin is common; however, in some patients, the severity of disease may be lower than prior to treatment.
Potential adverse effects of isotretinoin include dry skin and mucous membranes, hypertriglyceridemia, elevation of liver transaminases, vision changes, and teratogenicity. The side effects of isotretinoin are reviewed in detail separately. In the United States, participation in a Risk Evaluation and Mitigation Strategy program (www.ipledgeprogram.com) is required for isotretinoin prescriptions. (See "Oral isotretinoin therapy for acne vulgaris", section on 'Adverse effects'.)
Adjunctive interventions — Acute relief from the discomfort associated with an inflamed or suppurative nodule is sometimes necessary. Intralesional corticosteroid injections and incision and drainage can be used to provide rapid symptom relief. In addition, regular use of topical antimicrobial cleansers may help to reduce risk for secondary infection. These interventions do not alter the course of the disease and should not be used as primary treatment.
Intralesional corticosteroids — Intralesional injections of triamcinolone acetonide can provide temporary reduction of inflamed nodules. The typical dose range is 5 to 10 mg/mL, depending on the severity of inflammation. Higher concentrations (eg, 10 to 20 mg/mL) may be useful for the treatment of associated hypertrophic scarring. (See "Keloids and hypertrophic scars".)
Intralesional injection is best performed by clinicians experienced with this procedure. To minimize risk for corticosteroid-induced skin atrophy, the concentration and total volume of injection should be commensurate with the degree of inflammation or fibrosis, as well as the size of the individual lesion. (See "Intralesional corticosteroid injection".)
A 30-gauge needle can be used for injection. We usually do not inject more than 40 mg of triamcinolone acetonide per treatment session.
Incision and drainage — Incision and drainage is widely used for temporary relief of symptoms from suppurative nodules. (See "Techniques for skin abscess drainage".)
Topical antimicrobial cleansers — Washing the scalp with a topical antimicrobial cleanser (eg, chlorhexidine, povidone-iodine) is often recommended to reduce risk for secondary infection. We typically instruct our patients to use an antimicrobial cleanser to wash the entire scalp during showering or bathing on a daily basis.
Other therapies — Less common treatments associated with improvement in DCS in small numbers of patients include oral zinc, biologic tumor necrosis factor (TNF) inhibitors, and a variety of procedural therapies.
Oral zinc sulfate — Oral zinc sulfate was first described in a case report of a patient who showed complete healing after three months of therapy. Within the first three weeks, nodules disappeared and hair regrowth began in some areas. The patient continued treatment for a total of six months and experienced a relapse-free remission period of five years [37].
Successful treatment with oral zinc sulfate (135 mg three times per day) also occurred in an adolescent with DCS and acne conglobata [38]. Flattening of nodules occurred within four weeks and hair regrowth was noted after 12 weeks. In this patient, continued treatment with oral zinc sulfate at a reduced dose was necessary to maintain clinical improvement.
Biologic TNF inhibitors — Several case reports describe successful treatment of recalcitrant DCS with infliximab [39-41] and adalimumab [41-44]. Clinical improvement may be noted as early as the first few weeks of treatment [39,41,42,44]. However, long-term studies are lacking and cost is a frequent barrier to treatment.
Procedural therapies — For DCS refractory to medical therapy, procedural modalities including laser-assisted epilation [45,46], carbon dioxide (CO2) laser ablation [47], and surgical excision [48-50] have appeared beneficial in small numbers of patients. Aminolevulinic acid photodynamic therapy was associated with improvement in DCS in case reports and small case series [51-54]. X-ray epilation has fallen out of favor due to long-term safety concerns. Resolution of a fluctuant nodule refractory to medical therapy with use of a pressure dressing for four months is documented in a case report [55].
PROGNOSIS — Because DCS is a chronic disorder with frequent relapses, long-term follow-up is essential. Some hair regrowth may occur once the disease is satisfactorily controlled in sites where sufficient damage to the hair follicles has not occurred. Patchy scarring alopecia can develop in long-standing cases [15].
Rare complications include squamous cell carcinoma in long-standing disease [56] and calvarial osteomyelitis [57].
SUMMARY AND RECOMMENDATIONS
●Dissecting cellulitis of the scalp (DCS) is a chronic inflammatory disease of the scalp that can result in scarring and permanent hair loss. DCS most commonly affects men of African ancestry between the ages of 20 and 40; however, other individuals can develop DCS. (See 'Epidemiology' above.)
●The pathogenesis of DCS is unclear. The disease may result from a defect of follicular keratinization that leads to obstruction of hair follicles. DCS may occur in association with other follicular occlusive disorders. (See 'Pathogenesis' above and 'Associated disorders' above.)
●Patients with DCS typically develop multiple boggy, suppurative nodules on the vertex and posterior scalp with interconnecting sinus tracts (picture 1A-E). Purulent or bloody drainage is common. Hair loss is usually patchy. (See 'Clinical features' above.)
●A diagnosis of DCS usually can be made based upon the clinical evaluation. Scalp biopsies can be helpful for confirming DCS when the diagnosis is uncertain. A bacterial culture should be performed to rule out secondary infection. (See 'Diagnosis' above.)
●Data on the treatment of DCS are limited and the ideal approach to treatment is unclear. We suggest oral antibiotic therapy for initial therapy for patients with mild to moderate disease (Grade 2C). We suggest oral isotretinoin for initial therapy for patients with severe disease (Grade 2C). Intralesional corticosteroid injection and incision and drainage are useful adjunctive therapies for achieving rapid symptom relief. (See 'Treatment' above.)
