What Does Hidradenitis Suppurativa Look Like?

Authoritative Resource

HS vs Boils: Visual Comparison Guide

Side-by-side comparison of HS lesions and boils, with visual descriptions and diagnostic criteria to help you understand what you are seeing.

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One of the most frustrating aspects of hidradenitis suppurativa is that it looks different at different stages, and it can closely resemble other conditions like boils, cysts, or severe acne. This confusion is a major reason why HS takes an average of 7–10 years to diagnose correctly.

This guide describes every type of HS lesion in plain language, explains how they develop, and highlights the key differences between HS and similar-looking conditions.

This page uses descriptive language rather than clinical photographs out of respect for patient dignity. If you need clinical images for medical education, consult a dermatology atlas or speak with your physician.

Types of HS Lesions

HS produces several distinct types of lesions, and most patients experience multiple types simultaneously. Understanding each type helps you communicate more precisely with your doctor and track your disease progression.

Early / Stage I

Nodule

A firm, painful lump deep under the skin. Ranges from pea-sized to golf ball-sized. Red and warm to the touch. May not have a visible head.

Moderate / Stage I–II

Abscess

A fluctuant (soft, fluid-filled) swelling that may rupture and drain. Produces pus, blood, and serous fluid. Extremely painful before draining.

Moderate–Severe / Stage II–III

Sinus Tract (Tunnel)

A channel that forms under the skin connecting multiple abscesses. May drain continuously. Feels like a cord or rope under the skin. A hallmark of advanced HS.

Healed areas / All stages

Tombstone Comedone

Double-headed or dilated open pores that appear in areas of healed HS. They look like large blackheads and mark the sites of former tunnels.

Chronic / Stage II–III

Fibrotic Scar

Thick, rope-like bands of scar tissue that form after repeated flares. Can restrict movement in the armpits or groin. Permanent without surgical intervention.

How HS Looks as It Progresses

HS typically begins with isolated nodules and, without treatment, can progress to widespread scarring over years. The visual appearance changes dramatically across the three Hurley stages.

Hurley Stage I

What you see

One or a few red, painful lumps. Skin between lesions looks normal. No visible tunnels or significant scarring. Lesions may come and go, with clear skin between flares.

Hurley Stage II

What you see

Multiple recurrent abscesses. Some areas of permanent redness and thickened skin. Cord-like structures visible or palpable under the skin (sinus tracts). Scattered scarring between lesions.

Hurley Stage III

What you see

Entire regions of affected skin with diffuse redness, swelling, and drainage. Extensive rope-like scarring. Multiple open pores (tombstone comedones). Little or no normal skin in affected areas.

HS vs. Similar-Looking Conditions

Because HS is so frequently misdiagnosed, understanding how it differs from other conditions is critical for getting the right care.

Feature	HS	Boils	Cystic Acne
Location	Skin folds (armpits, groin)	Anywhere on body	Face, back, chest
Recurrence	Same spots, repeatedly	Usually does not recur	Widespread, not fixed
Tunnels (sinus tracts)	Yes, hallmark feature	No	No
Scarring	Progressive, permanent	Minimal	Possible but less severe
Cause	Immune/inflammatory	Bacterial infection	Hormonal/bacterial
Responds to antibiotics	Partially, temporarily	Yes, fully	Partially

How HS Looks on Different Skin Tones

HS affects people of all skin tones, but its appearance varies significantly. Most clinical descriptions and images historically focused on lighter skin tones, leaving many patients with darker skin without accurate reference points.

Lighter Skin Tones

Active lesions appear bright red to deep red-purple. Healed areas may leave pink or red marks that fade over time. Sinus tracts may be visible as bluish-purple cords under the skin.

Darker Skin Tones

Active lesions may appear dark brown, violet, or as a deepening of the natural skin tone. Post-inflammatory hyperpigmentation (dark spots) is very common and may be more prominent than in lighter skin. HS is actually more prevalent in people of African descent.

Research shows that HS disproportionately affects Black patients, who also tend to present with more severe disease at diagnosis, likely due to delayed diagnosis and healthcare access disparities. Advocating for yourself with a knowledgeable dermatologist is especially important.

Frequently Asked Questions

Does HS look like acne?

HS can resemble severe cystic acne, especially in early stages, which is one reason it is so frequently misdiagnosed. However, unlike acne, HS lesions appear in skin-fold areas (not typically the face), recur in the exact same spots, often connect under the skin through tunnels, and cause progressive scarring. Acne does not form sinus tracts.

What color are HS lesions?

HS lesions typically appear red to deep purple-red in lighter skin tones. In darker skin tones, they may appear as dark brown, violet, or hyperpigmented areas. After healing, lesions often leave behind darker patches (post-inflammatory hyperpigmentation) or rope-like scar tissue.

Do HS lesions always drain?

Not always. Some HS nodules remain firm and painful without ever draining (these are called blind nodules or non-fluctuant nodules). Others develop into abscesses that rupture spontaneously and drain a mixture of pus, blood, and serous fluid. Chronic sinus tracts may drain continuously.

What do HS scars look like?

HS scars can take several forms: rope-like fibrotic bands of scar tissue that restrict movement, pitted or atrophic scars (sunken areas), hypertrophic or raised scars, and open blackhead-like pores called tombstone comedones that mark the sites of healed tunnels. Extensive scarring is a hallmark of advanced HS.

How is HS different from a regular boil?

A regular boil (furuncle) is a single, acute infection of a hair follicle that typically resolves completely with treatment and does not recur in the same spot. HS lesions recur repeatedly in the same areas, form interconnected tunnels under the skin, cause progressive scarring, and are driven by immune system dysfunction rather than simple bacterial infection.