What is the diagnosis and treatment for foul-smelling discharge from a swelling under the axillary region?

Hidradenitis Suppurativa: Diagnosis and Management

The most likely diagnosis for foul-smelling discharge from an axillary swelling is hidradenitis suppurativa (HS), a chronic inflammatory disease requiring combined medical and surgical management, not simple abscess drainage. 1

Clinical Diagnosis

Diagnosis is clinical and requires three key features:

• Typical lesions: painful inflammatory nodules, abscesses, draining sinus tracts, and scarring 1
• Characteristic location: axillae (most common), groin, perianal, perineal, and inframammary regions 1, 2
• Recurrent nature: chronic, relapsing course with repeated flares 1

The foul-smelling discharge is pathognomonic - patients drain thick, mucopurulent fluid with a characteristic odor that significantly impacts quality of life 3, 2, 4. This distinguishes HS from simple bacterial abscesses, which typically present as acute, isolated events 5.

Key Distinguishing Features from Simple Abscess

Do not mistake HS for a simple cutaneous abscess requiring only incision and drainage. Critical differences include:

• Open comedones with double heads are characteristic of HS and not seen in typical abscesses 2
• Rope-like subcutaneous scarring and sinus tracts develop over time in HS 2, 4
• Multiple recurrent lesions in the same anatomic region indicate HS rather than isolated infection 1, 5
• Bilateral axillary involvement strongly suggests HS over simple infection 1

Severity Assessment

Use Hurley staging to guide treatment decisions: 1, 2

• Stage I: Recurrent nodules/abscesses without sinus tracts or scarring
• Stage II: One or limited number of sinus tracts with scarring in a body region
• Stage III: Multiple/extensive sinus tracts and scarring across an entire region

Treatment Algorithm

Treatment must be tailored to Hurley stage and combine medical plus surgical approaches: 1, 3

For Hurley Stage I:

• Topical or oral antibiotics (clindamycin, rifampin combinations) 1
• Lifestyle modifications: smoking cessation, weight loss 3
• Incision and drainage only for acute abscesses - but recognize this is NOT curative 1

For Hurley Stage II-III:

• TNF-alpha inhibitors (adalimumab) are now first-line for moderate-to-severe disease 1, 3
• Wide surgical excision of affected tissue, not simple drainage 1
• Combined antibiotic, anti-inflammatory, and surgical treatment achieves best results 3

Critical Management Pitfalls

Avoid these common errors that lead to treatment failure:

• Never treat HS with simple incision and drainage alone - this addresses only the acute abscess but not the underlying disease, leading to inevitable recurrence 1, 5
• Do not prescribe short antibiotic courses as if treating cellulitis - HS requires prolonged therapy or biologics 1
• Do not delay specialist referral - early aggressive treatment prevents progression to disabling Stage III disease 3, 4
• Recognize that cultures are typically polymicrobial and do not represent simple bacterial infection requiring only antibiotics 1

Transitioning to Definitive Care

Emergency or acute care management should focus on:

• Pain control - HS lesions are severely painful and debilitating 4
• Drainage of fluctuant abscesses for symptomatic relief only 1
• Urgent dermatology or surgery referral within days, not weeks 5
• Patient education that this is a chronic inflammatory condition, not recurrent "boils" from poor hygiene 1, 4

The diagnosis should be suspected in any patient with recurrent, painful axillary swellings with foul discharge, especially in women aged 20-40 years. 4 Missing this diagnosis leads to years of inappropriate treatment with repeated drainage procedures and antibiotics without addressing the underlying inflammatory pathology.