The appearance of a bump under the armpit can be uncomfortable and sometimes painful. While many harmless causes can trigger this type of skin lesion, certain medical conditions, such as hidradenitis suppurativa, may explain the recurrent presence of abscesses or inflammatory nodules under the arms. Understanding the symptoms and the differences between a simple bump and an underlying condition helps ensure more appropriate care.
Causes of bumps under the armpits
The armpits are an area prone to irritation due to the presence of sweat glands and hair follicles. A bump under the armpit may be caused by several factors:
Irritation or friction from shaving or waxing.
A hair follicle infection (folliculitis), often caused by bacteria.
Excessive sweating, which promotes bacterial buildup and clogged pores.
An allergic reaction to certain deodorants or hygiene products.
However, when these lesions become recurrent and painful and are accompanied by deep subcutaneous nodules, it may be a sign of hidradenitis suppurativa.
Hidradenitis suppurativa: a chronic inflammatory disease
Hidradenitis suppurativa is an inflammatory skin disease affecting the apocrine sweat glands, mainly located under the armpits but also in the groin area, on the buttocks and under the breasts. Unlike a simple bump under the armpit, this condition causes painful and persistent nodules that can develop into abscesses and leave scars.
How to recognize armpit bumps caused by hidradenitis suppurativa?
Several signs can help differentiate a temporary irritation or infection from hidradenitis suppurativa. This chronic dermatological condition is characterized by:
Deep nodules under the skin that are often painful.
Recurrent abscesses that may break and release pus.
Chronic inflammation with periods of flare-ups and remission.
Scars and fistulas in more advanced cases, caused by repeated lesions.
Hidradenitis suppurativa is a chronic condition whose exact causes remain unclear. It is, however, associated with genetic factors and immune system dysfunction.
A bump under the armpit can be harmless and disappear quickly, but in some cases, it may be a sign of hidradenitis suppurativa, a chronic inflammatory disease that requires specific management. Medical follow up helps establish an accurate diagnosis and implement appropriate treatment to reduce flare-ups and improve quality of life.
The Saint-Louis Research Center regularly conducts clinical studies on hidradenitis suppurativa and other dermatological conditions. You can consult the list of ongoing clinical studies to learn more.