Dissecting cellulitis of the scalp, also known as perifolliculitis capitis abscedens et suffodiens (PCAS), is a neutrophilic scarring alopecia with an abnormal inflammatory response to staphylococcal antigens. This association is linked to a propensity for follicular occlusion and dramatic secondary inflammatory changes to proinflammatory stimuli, such as bacterial infection. The follicle occludes, dilates, and ruptures, and the keratin promotes an inflammatory response in conjunction with a secondary staphylococcal infection attracting neutrophils.
The condition typically affects black men between the ages of 20 and 40, but it can occur in other ethnicities, in women, and in children. Dissecting cellulitis usually affects the vertex (although the entire scalp can be involved), producing boggy or fluctuant pustules and nodules. Patients complain of pain and of a disfiguring appearance. If a nodule is pressed, pus or serosanguineous fluid may extrude from one or more of the orifices.
The disease may wax and wane over several years, later producing dermal fibrosis, sinus tracts, and hypertrophic scarring with alopecia. There is an increased risk of squamous cell carcinoma in patients with long-standing disease.
ICD10CM: L66.3 – Perifolliculitis capitis abscedens
SNOMEDCT: 77333008 – Dissecting cellulitis of scalp
Differential Diagnosis & Pitfalls
Acne (folliculitis) keloidalis nuchae – Presents on the occipital scalp and nape of neck with follicular papules and pustules. A skin biopsy reveals chronic inflammation, diffuse destruction of hair follicles, scarring, and fibrosis.
Folliculitis decalvans – Presents on the occipital and vertex scalp with erythematous follicular papules and pustules with scarring and yellow-gray scale surrounding the follicle. There may be erosions, hemorrhagic crust, and tufted hair. A skin biopsy may reveal deep perifollicular or intrafollicular mixed infiltrate of lymphocytes, histiocytes, or plasma cells without abscess or sinus tract formation.
Cellulitis or erysipelas – In contrast to classic cellulitis, dissecting cellulitis of the scalp demonstrates prominent nodularity.
Dissecting cellulitis of the scalp, also known as Hoffman disease and perifolliculitis capitis abscedens et suffodiens, is an inflammatory condition resulting in patchy hair loss on the scalp that may be scarring.
The cause is unknown but is thought to involve a blockage of the hair follicle that causes rupture of the follicle and a chronic inflammatory response.
Dissecting cellulitis of the scalp is classified as a chronic inflammatory scarring alopecia. It has a variable presentation and has a similar presentation to other conditions, causing this condition to be underreported. It may be painful and may cause individuals with the condition to suffer from psychologic distress or social isolation because of their feelings relating to symptoms of the disease, including hair loss.
Although there is currently no cure for this condition, it can be treated with steroids, antibiotics, other medications, and sometimes surgery.
Who’s At Risk
Dissecting cellulitis of the scalp typically affects Black men aged 20-40 years but is not limited to this demographic.
Signs & Symptoms
The clinical presentation of this condition can vary. There may be nodules, pustules, abscesses, and scarring alopecia.
There may be no symptoms or there may be pain.
It is important to avoid physical manipulation of the lesions on the scalp, as this can lead to increased scarring and inflammation.
Avoid hair products with oil as the main ingredient, as this may add to the follicular blockage.
Pain associated with the condition can be managed with over-the-counter pain medication.
Some patients opt to wear wigs or other hair pieces for the hair loss caused by this condition.
When to Seek Medical Care
If you notice lumps, bumps, or lesions that sometimes ooze pus or you have patchy hair loss on the scalp, it is important to see a doctor. A fever can also indicate an infection associated with dissecting cellulitis of the scalp.
This condition is usually diagnosed with clinical examination of the scalp. If the diagnosis is inconclusive, a biopsy can be performed.
Treatments your physician may prescribe:
There is no cure, so treatment of this condition involves management of symptoms. Antibiotics such as minocycline, clindamycin and rifampin, or ciprofloxacin, and intralesional corticosteroid injections can help to diminish inflammation. Isotretinoin and dapsone are sometimes used.
Sometimes laser treatments are used to control skin lesions and scarring.
In severe cases, excisional surgery is performed with reconstructive skin grafting.