My patient has painful pustules and nodules in her axillae.  How can I distinguish hidradenitis suppurativa (HS) from folliculitis or recurrent skin abscesses?

A key differentiating factor between hidradenitis suppurativa (HS) and more common conditions such as folliculitis or recurrent abscesses is the location and recurrence pattern of the lesions. HS is clinically diagnosed based on the following typical lesion characteristics:

  • Morphology: open comedones, pustules, painful nodules, abscesses, sinus tracks and scarring; 
  • Distribution: intertriginous or apocrine gland-rich areas, such as the axillae, inframammary folds, lower abdomen/waist, gluteal cleft, groin and inner thighs; and
  • Frequency: recurrent lesions in the same locations, with at least two or more episodes in six months1,2

In contrast, folliculitis involves inflammation of the hair follicle and may present with pustules or boils; however, lesions are superficial, occur anywhere hair is present, and are not complicated by deep nodules, sinus tracks or scarring.2

Although recurrent abscesses may mimic HS, they are typically unilateral or asymmetric, fluctuant and caused by bacterial infection with positive wound cultures. In contrast, HS is frequently a symmetric, sterile inflammatory condition unless secondarily infected. Additionally, abscesses generally respond to incision and drainage and antibiotics and do not result in sinus tracks or scarring.2

Once you suspect HS, your management may be guided by its severity using the following disease stages (Hurley staging).

  • Mild disease (Hurley stage I): localized lesions without sinus tracks or scarring. Treat with antimicrobial washes (chlorhexidine) and topical antibiotics (clindamycin).3
  • Moderate disease (Hurley stage II): typical lesions in multiple locations with or without sinus tracks and scarring. Treat with antimicrobial washes, topical antibiotics, and systemic antibiotics (tetracyclines or clindamycin). Consider adding rifampin, metronidazole, or moxifloxacin in refractory cases.3
  • Severe disease (Hurley stage III): diffuse painful lesions with extensive sinus tracks and scarring. Requires dermatology referral for consideration of biologics (eg, adalimumab), laser, parenteral antibiotics and/or surgical interventions.3

Across all stages of severity, patients should be counseled on smoking cessation, weight loss, diet modification and appropriate pain management.4 Acute flares may be treated with warm compresses, tetracyclines, and intralesional steroids.3 Incision and drainage is reserved for severe, painful lesions as routine drainage could worsen tunneling.5

Bonus Pearl: Did you know the average diagnosis delay for HS is up to 10 years?2 Primary care physicians have a unique position in early recognition and treatment of this debilitating disease.

Contributed by Taylor Lynch, MD, Mercy Hospital-St. Louis, St. Louis, Missouri

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References:

  1. Wieczorek M, and Walecka I. Hidradenitis suppurativa – known and unknown disease. Reumatologia 2016: 56: 337-339. doi:10.5114/reum.2018.80709. https://pubmed.ncbi.nlm.nih.gov/30647478/.
  2. Snyder, CL, Chen XL, Porter ML. Obstacles to early diagnosis and treatment of hidradenitis suppurativa: Current Perspectives on Improving Clinical Management. Clin Cosm Invest Derm 2023;16:1833-1841. doi:10.2147/CCID.S301794. https://pmc.ncbi.nlm.nih.gov/articles/PMC10361090/.
  3. Alikhan A, Sayed C, Alavi A, et al. North American clinical management guidelines for hidradenitis suppurativa: A publication from the United States and Canadian Hidradenitis Suppurativa Foundations: Part II: Topical, intralesional, and systemic medical management. J Am Acad Derm 2019;81:91-101. doi:10.1016/j.jaad.2019.02.068. https://pubmed.ncbi.nlm.nih.gov/30872149/.
  4. Hermak S, and Lev-Tov H. Integrative approaches in the management of hidradenitis suppurativa. J Am Acad Derm 2024;91: S42-S45. doi:10.1016/j.jaad.2024.09.016. https://pubmed.ncbi.nlm.nih.gov/39626999/.
  5. Chawla S, Toale C, Morris M, et al. Surgical management of hidradenitis suppurativa: A narrative review. J Clin Aesth Derm 2022;15: 35-41. https://pubmed.ncbi.nlm.nih.gov/35309275/.

Disclosures/Disclaimers: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

My patient has painful pustules and nodules in her axillae.  How can I distinguish hidradenitis suppurativa (HS) from folliculitis or recurrent skin abscesses?

My patient just developed a fixed drug reaction from ibuprofen. What is the mechanism of this type of skin reaction?

Although its mechanism is not full elucidated, fixed drug eruption (FDE) is thought to result from the drug-induced cytotoxic activation of CD8+ memory T cells.1 ,2

In this context, the culprit medication behaves as a hapten that adheres to basal keratinocytes which in turn results in the recruitment of T cells and inflammation.  However, as the inflammation resolves, CD8+  effector-memory T cells remain in the area in question,  setting the stage for more rapid immunologic reaction when the drug is reintroduced.

Why a systemic drug triggers a reaction only at specific sites in the body is a fascinating question. Prior herpes simplex virus (HSV) infection (eg, on the lips or genitalia) may explain some cases.1 Interestingly, despite the absence of prior herpetic lesions, most patients with FDE are seropositive for HSV. Previously traumatized body sites (e.g. from burns or insect bites) may also create an immune microenvironment conducive to FDE.

The classic presentation of FDE is reappearance of a rash in the genitals, perianal areas, hands, and feet within 30 min to 8 hours of taking the culprit medication.3 Look specifically for NSAIDs, tetracyclines, sulfonamides, and aspirin on the patient’s drug list. 4

References

  1. Shiohara, T. Fixed drug eruption: Pathogenesis and diagnostic tests. Curr Opin Allergy Clin Immunol 2009; 9:316-21. https://www.ncbi.nlm.nih.gov/pubmed/19474709
  2. Butler, DF. Fixed Drug Eruptions. Medscape. http://emedicine.medscape.com/article/1336702-overview#a4. Accessed March 26, 2018.
  3. Korkij W, Soltani K. Fixed drug eruptions: A brief review. Arch Dermatol 1984;120:520. https://www.ncbi.nlm.nih.gov/pubmed/6231004
  4. Oakley, A. Fixed Drug Eruption. https://www.dermnetnz.org/topics/fixed-drug-eruption Accessed March 26, 2018.

 

Contributed by Amir Hossein Ameri, Medical Student, Harvard Medical School

My patient just developed a fixed drug reaction from ibuprofen. What is the mechanism of this type of skin reaction?