HIDRADENITIS SUPPURATIVA (ACNE INVERSA)
Hidradenitis suppurativa (acne inversa) is a rare chronic, life-altering disease. It can be an isolated clinical finding, or it can be associated with cystic acne, dissecting cellulitis of the scalp, and pilonidal cysts.
Clinical Findings: Hidradenitis suppurativa is most commonly encountered in postpubertal women. The ratio of female-to-male involvement is approximately 4:1. This condition preferentially affects areas that are rich in apocrine glands and terminal hairs. The areas most commonly involved are the axillae, groin, and inframammary folds. It is rare in other areas. Hidradenitis suppurativa starts as tiny red papules or nodules that tend to be folliculocentric. The papules are tender and firm to palpation. At this point, the differential diagnosis includes an early folliculitis or furunculosis. As the disease progresses, the hard nodules become fluctuant and spontaneously drain to the surface of the skin. The nodules may coalesce into plaques with varying amounts of scarring. The longer the process has been going on, the more scarring is prevalent. Eventually, sinus tracts develop that interconnect multiple subcutaneous nodules with multiple cutaneous openings. Clinically, pressing on one of the nodules may produce drainage from a distant sinus tract. The disease is relentless, and new crops of lesions repeatedly develop. Pain is significant and is a main cause of morbidity. Obesity tends to be seen in association with hidradenitis suppurativa. Hidradenitis has been seen in association with Crohn’s disease, and some believe that hidradenitis suppurativa is a cutaneous form of Crohn’s disease. Long-standing disease has been associated with the development of squamous cell carcinoma. The tumors tend to be large at diagnosis
The drainage from the cutaneous nodules often requires extensive bandaging to keep clothing from getting soiled. The drainage has a malodorous, foul smell. The draining sinus tracts and nodules are often colonized with various bacteria, and cultures of the purulent drainage show growth of a number of different organisms, including Staphylococcus aureus and streptococcal species. However, this is not primarily an infectious disease. The bacteria in these cases are present secondary to the underlying inflammatory condition and the lack of normal cutaneous skin barrier function. Pathogenesis: Hidradenitis suppurativa is an inflammatory disease with secondary bacterial superinfection and colonization. Routine culturing of the nodules and the drainage is often sterile. Hidradenitis is theorized to be caused by rupture of the mature follicular epithelium along areas of apocrine glands; hence, its propensity to occur in areas with high densities of apocrine glands. A hormonal control over the process has been theorized, given that it is more common in postpubertal women and in obese individuals. Once the hair follicle ruptures, an inflammatory cascade is set off and causes the resulting nodules, cysts, fistulas, and scarring. It appears to be a self-perpetuating process. The exact mechanism by which this occurs is unknown.
Histology: Chronic lesions show a dense, mixed inflammatory infiltrate with abscess and sinus tract formation. Varying amounts of fibrosis and scar tissue are present. Apocrine gland inflammation can be appreciated in a fair number of cases. The inflammation extends into the subcutaneous tissue.
Treatment: Therapy is often aimed at reducing inflammation and bacterial superinfection. There is no curative therapy, and most treatments have only anecdotal reports of success. Topical clindamycin and other antibacterial products such as benzyl peroxide are often the first-line agents employed for mild disease. Oral antibiotics, typically in the tetracycline class, are often used because they have both antiinflammatory and antibacterial properties. Weight loss must be advocated. Other agents that have had limited success include isotretinoin, etanercept, and infliximab. Surgical options include wide local excisions to remove the affected tissue and repair with complex flap closure. Liposuction has also been tried in an attempt to remove the affected apocrine gland hair follicle unit. The only potential for cure is with a surgical approach. This approach seems to work best for axillary disease; groin and inframammary disease almost always recurs after surgery. It is also of the utmost importance to address patients’ psychosocial needs, because this disease has a devastating toll on the patients it afflicts.