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FOLLICULAR OCCLUSION TRIAD

The follicular occlusion triad represents a group of diseases that commonly coexist, namely:

•	hidradenitis suppurativa,
•	acne conglobata, and
•	dissecting cellulitis.

The first two will be discussed in turn here, and the latter in Ch. 28.

Hidradenitis suppurativa

Etiology and pathogenesis

This disease is often mistaken for a bacterial infection, as it presents with what looks like recurrent 'boils' in the groin and axilla. It actually seems to result from clogged pores, much like acne. Any bacterial infection is secondary. Although the disease affects areas inhabited by apocrine glands, it appears to be a process of poral occlusion of the pilosebaceous unit with secondary inflammation of the apocrine glands. Histology of early lesions shows an occluding spongiform infundibulofolliculitis. It is also more prevalent in hirsute women, and either more prevalent or more troublesome in obese individuals. Smoking and hidradenitis suppurativa may be linked.

Clinical

The patient presents with inflammatory nodules and sterile abscesses in the groin (Fig.10.36), the axilla (Fig. 10.36), the inframammary area, or the perianal area. Later, with chronic inflammation, sinus tracts, fistulas, and hypertrophic scarring develop. Activity in the axilla is most common. One site only or all sites may be affected. Rarely, in severe cases, lesions may develop on the extremities (Fig.10.36). Women are more commonly affected, with onset from puberty to middle age.

     This disease may occur with other diseases of the follicular occlusion triad (acne conglobata and perifolliculitis capitis abscedens et suffodiens). As noted earlier, initial lesions are sterile. Later, secondary infection occurs, most commonly with staphylococci, streptococci or Escherichia coli. Other organisms that may be found include Bacillus proteus, Pseudomonas spp., Streptococcus milleri and anaerobes (e.g. Bacteroides spp.). Squamous cell carcinoma may rarely be a complicating factor, most commonly in the anogenital region. Often there is a delay in diagnosis, and metastasis and death are common. Any chronic, non-healing areas should be biopsied.

Differential diagnosis

The usual diagnosis in patients with hidradenitis suppurativa, often over many years, is 'recurrent boils' or 'cysts'. The importance of applying the correct label, as outlined in the following Treatment section, is that the approach to antibiotic treatment, both in terms of duration and choice of agent, differ from the treatment of simple infected follicles that constitute a boil.

Treatment

Reduction of friction by weight loss and the avoidance of tight - fittingclothing should be recommended. Tight clothing and bras for women with inframammary disease should be avoided as much as possible. Any smokers should quit.

     Once lesions have become chronic, and especially if drainage is present, antibiotics, both topical (e.g. clindamycin) and oral, are helpful. Typically recommended oral agents are tetracycline, oxytetracycline or erythromycin (all 1 - 2g/day in divided doses), trimethoprim - sulfamethoxazole or minocycline (100mg twice a day). Culture for both anaerobes and aerobes may direct therapy (e.g. clindamycin orally for Bacteroides spp.). Other than occasional short-term use if a specific infection has been identified, it is vital that antibiotic therapy is used for prolonged periods, sometimes indefinitely, as it is probably their antiinflammatory properties as well as antiinfection properties that are important; this is why the agents of choice and the stress on adequate duration of use are similar to those recommended for acne. Daily use of an antiseptic soap may be helpful.

    Exteriorization of chronically draining sinuses, or incision and drainage of an acutely tender fluctuant lesion, may be necessary, but neither constitutes adequate long-term surgery, and such procedures may add to the scarring. Courses of isotretinoin and acitretin have met with some success, and it has been suggested that acitretin is more effective than isotretinoin; however, the requirement to abstain from pregnancy for 2 years after stopping the drug is a major disincentive. Prednisone or prednisolone 40 - 60mg may be given for 1 - 2 weeks for acute, severe flares. Despite all these interventions, the patient often develops new lesions and is a frequent visitor to the doctor's office for intralesional injection of early lesions with triamcinolone (2.5 - 5.0mg/mL).

     Premenstrual exacerbation is common in female patients and, for them, antiandrogen therapy can be quite helpful. In the USA, spironolactone may be given. In the UK and elsewhere, cyproterone acetate (50 - 100mg, days 5 - 15 of the menstrual cycle) with Dianette is recommended. Anecdotally, and probably logically, this approach seems to be more effective in those with a premenstrual flare than in those who do not report this, although it is worth trying in any female patient without contraindications to hormonal treatment.

     For definitive, wide surgical excision with healing by secondary intention should be performed, preferably by someone with experience in this area. This intervention may seem excessive, but the patient may welcome this approach after suffering for years with many tender, draining lesions. Narrow excision of inflamed areas has a high recurrence rate.

    Although surgery remains the treatment of choice for severe hidradenitis suppurativa, infusion of infliximab has proved benificial in selected patients.

Figure 10.36  Hidradenitis suppurativa. (a) Multiple inflammatory lesions of the vulva. Intralesional triamcinolone is often helpful for early lesions that have not drained. (b) Hidradenitis suppurativa of the axilla. This is the classic appearance, with inflammatory nodules and scarred areas. This condition is commonly misdiagnosed as a bacterial infection. (c) Hidradenitis suppurativa of the axilla. A close-up view of the draining pus. When intact, the lesions represent sterile abscesses. Once open, they may become secondarily infected. (d) Acne conglobata of the leg. A rare variant seen in severe disease. Intralesional triamcinolone may be given for early lesions. More established lesions may be healed with curettage and desiccation, but scarring is significant.

Acne conglobata

Etiology and pathogenesis

Acne conglobata is a specific variant of acne characterized by the large comedones with multiple openings. The face and back are typically affected, and the course is chronic. An inherited susceptibility to this disease is likely, and a positive family history is often elucidated. Some patients with acne conglobata may have chronic peripheral oligoarthritis, which is indistinguishable radiologically from the classic, seronegative spondyloarthropathies (e.g. Reiter syndrome and psoriatic arthritis).

Clinical

The patient is affected with multiple comedones, inflammatory nodules with pus, scarring, and sinus tracts of the back, buttocks, face and chest (Fig.10.37). The characteristic lesion of this disease is a large 'fistulated' or 'bridged'comedone with multiple openings (Fig.10.37). This disease most commonly affects young males, and may occur alone or in combination with other diseases of the follicular occlusion triad (hidradenitis suppurativa and perifolliculitis capitis abscedens et suffodiens). Acne conglobata and a generalized lichen spinulosa - like eruption have recently been reported in patients with HIV.

Treatment

Oral antibiotics, such as tetracycline (500mg twice a day) or other antibiotics, as directed by culture, may be tried. A course of isotretinoin is recommended by many but is not as effective as in acne vulgaris. Incision and drainage of acutely inflamed or fluctuant areas may be necessary. Chronically draining sinus tracts may need to be externalized.
Dissecting cellulitis of the scalp

See Chapter 28.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.