Dissecting cellulitis of scalp - Cellulitis DDx
The condition typically affects Black men between the ages of 20 and 40, but it can occur in other races and 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.
Dissecting cellulitis may be isolated or may occur as part of a follicular occlusion triad that includes acne conglobata and hidradenitis suppurativa or a tetrad that additionally includes pilonidal cysts.
It has been rarely associated with skull osteomyelitis, arthritis with keratitis, pyoderma vegetans, pityriasis rubra pilaris, keratitis-ichthyosis-deafness syndrome, Crohn disease, and pyoderma gangrenosum.
In contrast to classic cellulitis, dissecting cellulitis of the scalp demonstrates prominent nodularity. Lesions may be fluctuant and/or draining. Location and patient demographic factors, such as race, are important diagnostic clues.
L66.3 – Perifolliculitis capitis abscedens
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.
- Pseudopelade of Brocq
- Tinea capitis
- Ruptured epidermoid cysts
- Pilar cyst
- Contact dermatitis
- Mycobacterial infection
- Erosive pustular dermatosis of the scalp
- Lichen planopilaris
- Folliculotropic mycosis fungoides with large cell transformation
- Cutis verticis gyrata
- Malignant proliferating pilar cysts
- Alopecic and aseptic nodules of the scalp