A Case Report for Ectopic Hidradenitis Suppurativa on the Posterior Neck
Introduction
Hidradenitis suppurativa (HS) is a chronic, inflammatory, and recurrent skin condition where nodules, abscesses, and fistulas with purulent secretions are present. It commonly occurs in skin folds where apocrine glands exist—as in the axillae, inguinal region, and perianal area.1-3 It usually starts in early adulthood and affects more frequently the female sex and Afro-American population. The global prevalence is calculated between 0.05 - 4.10%, ethnicity with genetic and environmental factors are possibly involved.1
Cases with atypical locations like the mandibular jaw line4, dorsal foot5, posterior thigh6, and others7,8 where apocrine glands do not prevail have been reported. We present a case of ectopic HS affecting the posterior neck.
Case
The patient profile was an 11-year-old female with central obesity (BMI: 35.1) and marked acanthosis nigricans on the posterior neck and axillae. She had a history of weightlifting, using the posterior neck as a supporting point for the bar and weight load. The patient presented a 1-year history of subcutaneous nodules with hematic and purulent secretion, progressing to the formation of sinus tracts on the posterior neck (Fig. 1a, b). The wound culture was positive for Cutibacterium acnes. The hematoxylin-eosin biopsy showed necrosis with a mixed inflammatory process of lymphocytes, histiocytes, and polymorphonuclear leukocytes, as well as abscess formation, foreign body granulomatous reaction, and the presence of granulation tissue (Fig. 2). Both PAS and Ziehl-Neelsen stains were negative.
The initial treatment consisted of wound drainage and oral antibiotics (minocycline and lymecycline) for periods of one to two months and nonsteroidal anti-inflammatory drugs with partial resolution. Hair removal with 808 nm diode laser was also performed on the area.
Despite the therapeutic interventions, fistulas and abscesses relapsed. The patient was started on isotretinoin treatment (0.5 mg/kg/day) (Fig. 1c, d) with significant improvement.
FIGURE 1
FIGURE 2
Discussion
In this case, the diagnosis was not straightforward considering that the only part of the body compromised was the posterior neck. We believe that continued mechanical stress played an important role, as it contributed to the formation of micro comedones. This can be exacerbated by friction of the body folds.2,9 Obesity, combined with a history of weightlifting using substantial posterior neck support, could be a determining factor for the development of the disease. Indications of obesity increase the pro-inflammatory state, in addition to the formation of skin folds, creating the ideal environment for the growth of bacteria such as Prevotella and Porphyromonas spp, and Staphylococcus aureus.2 Corynebacterium spp, Acinetobacter spp, Moraxella spp, Staphylococcus epidermidis, and Cutibacterium acnes were also identified.10
Multiple complex mechanisms lead to the progression of chronic inflammation in HS. The initial symptoms were perivascular with follicular inflammatory infiltrate, as well as hyperkeratosis and infundibular hyperplasia. This promotes follicular plugging and dilation with the activation of macrophage and pro-inflammatory cytokines such as TNF and IL-1β, causing the arrival of neutrophils and inducing the formation of abscesses and fistulas.1
Therapeutic options include: antibiotic therapy with tetracyclines, intralesional glucocorticoids, CO2 and Nd:YAG lasers, antiandrogens, isotretinoin, immunosuppressive therapy with cyclosporine and TNF inhibitors, and surgery.11 The use of oral isotretinoin, as in our case, has been reported in retrospective studies as an effective treatment for reducing outbreaks, improving existing lesions, and reducing sebum excretion with long lasting results for up to nine years.12
Conclusion
HS is a chronic inflammatory skin condition that has been mainly associated with inflammation of the apocrine gland. But recent reports have mentioned the emergence of this condition in areas where these glands do not predominate, and the importance of mechanical stress and friction in the pathogenesis of this disease has been emphasized.1,4,5,6
References:
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2Goldburg S, Strober B, Payette M. (2020). Hidradenitis suppurativa. Journal of the American Academy of Dermatology, 82(5), 1045-1058.
3Saunte D, Jemec G. (2017). Hidradenitis Suppurativa: Advances in Diagnosis and Treatment. JAMA, 318(20), 2019.
4Castrillón Velásquez M, Kim M, Tan M, et al. (2017). An Atypical Localized Form of Hidradenitis Suppurativa of the Jawline and Neck Mimicking Severe Cystic Acne on Presentation. Skin Appendage Disorders, 3(4), 215-218.
5Rondags A, Diercks G, Werker P, et al. (2017). Ectopic Hidradenitis Suppurativa on the Dorsal Foot of a Road Maker. JAAD Case Reports, 3(5), 429-431.
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9Boer J, Jemec G. (2020). Mechanical Forces and Hidradenitis Suppurativa. Experimental Dermatology, 30(2), 212-215.
10 Ring H, Thorsen J, Saunte D, et al. (2017). The Follicular Skin Microbiome in Patients with Hidradenitis Suppurativa and Healthy Controls. JAMA Dermatology, 153(9), 897-905.
11Chero H, Herlin C, Bekara F, et al. (2019). Hidradenitis Suppurativa: A Systematic Review and Meta-analysis of Therapeutic Interventions. Indian Journal of Dermatology, Venereology and Leprology, 85(3), 248-257.
12Chu S, Michelle L, Ekelem C, et al. (2020). Oral Isotretinoin for the Treatment of Dermatologic Conditions Other than Acne: A systematic review and discussion of future directions. Archives of Dermatological Research, 313(6), 391-430.
Tagged: Clinical dermatology & dermatologic surgery, Lasers, EBD & body shaping
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