Hidradenitis Suppurativa Between the Buttocks: Presentation and Differential Diagnosis
Clinical Presentation
Hidradenitis suppurativa (HS) in the intergluteal/perianal region presents with painful, deep-seated nodules, abscesses, draining sinus tracts, and scarring in the skin between the buttocks, representing one of the characteristic anatomical sites for this chronic inflammatory disease. 1
Key Clinical Features to Identify
- Primary lesions: Deep-seated, painful inflammatory nodules and abscesses that develop in the intergluteal cleft and perianal skin 1
- Secondary lesions: Draining tunnels (sinus tracts), chronic suppuration with malodorous discharge, and morbid scarring from chronic inflammation 1
- Distribution pattern: Lesions occur in apocrine gland-bearing skin, with the perianal and perineal region being the third most common site after axillae and groins 2
- Chronicity: Recurrent, relapsing course with lesions that persist for weeks to months, often with new lesions developing while old ones are healing 1
- Age of onset: Typically begins in the second or third decade of life (18-39 years) 3
Disease Severity Assessment
- Hurley Stage I: Isolated nodules and abscesses without sinus tracts or scarring 4
- Hurley Stage II: Recurrent nodules with limited sinus tracts and scarring 4
- Hurley Stage III: Diffuse involvement with interconnected sinus tracts and extensive scarring across the entire affected area 5
Differential Diagnosis
Primary Differentials to Exclude
- Perianal abscess/fistula: Typically presents as a single acute abscess near the anal verge, often associated with anorectal pathology rather than multiple chronic lesions in apocrine-bearing skin 2
- Crohn's disease with perianal involvement: Look for gastrointestinal symptoms, perianal fistulas communicating with the rectum, and absence of lesions in other typical HS sites (axillae, groin) 5
- Pilonidal disease: Occurs specifically in the sacrococcygeal region with midline pits and sinus tracts, not extending to the perianal area or other intertriginous sites 2
- Furuncles/carbuncles: Acute, isolated staphylococcal infections that resolve completely with treatment, lacking the chronic relapsing pattern and tunnel formation of HS 2
- Actinomycosis: Rare chronic bacterial infection with sulfur granules on drainage, typically following trauma or surgery 2
Features That Distinguish HS
- Multiple anatomical sites: HS typically affects axillae, groins, and/or inframammary areas in addition to perianal region, whereas mimics are usually localized 1, 2
- Chronic relapsing course: New lesions develop while old ones heal, creating a pattern of persistent disease over months to years 1
- Double-ended comedones: Pathognomonic finding of paired comedonal openings connected by a subcutaneous tract 1
- Absence of rectal communication: Unlike Crohn's perianal disease, HS sinus tracts do not communicate with the anal canal 5
Initial Assessment Requirements
- Examine all intertriginous areas (axillae, groins, inframammary, perianal) to determine total disease burden and confirm diagnosis 4
- Document Hurley stage for the worst affected region to guide treatment intensity 4, 5
- Measure baseline pain using Visual Analog Scale (VAS) 4, 5
- Assess quality of life using Dermatology Life Quality Index (DLQI) 4
- Screen for comorbidities: Depression/anxiety, diabetes, hypertension, hyperlipidemia, inflammatory bowel disease 4, 5
Critical Pitfalls to Avoid
- Do not mistake HS for simple perianal abscess: HS requires chronic disease management, not just incision and drainage 5
- Do not delay dermatology referral for Hurley Stage III disease: Extensive perianal involvement (>15x15cm) requires immediate specialist evaluation for combined medical-surgical management 5
- Do not overlook other anatomical sites: Failure to examine axillae and groins may lead to underestimation of disease severity 4
- Do not miss inflammatory bowel disease: Screen for GI symptoms given the association between HS and Crohn's disease 4, 5