Large, dark openings and unusual lumps on the back can look alarming, especially when they contain hardened material or produce thick drainage. One possible explanation is an epidermoid cyst, a common skin growth that develops when skin cells become trapped beneath the surface. As keratin, a protein naturally found in the skin, accumulates inside the cyst, it can gradually form a noticeable lump with a dark central opening.

Another possible cause is a condition called a dilated pore of Winer. This occurs when a hair follicle becomes unusually enlarged and fills with accumulated keratin, creating a large, dark-looking opening. In some cases, multiple lumps, scars, and draining areas may also be associated with chronic inflammatory skin conditions such as hidradenitis suppurativa, although this condition more commonly affects skin folds.

Treatment depends on the underlying cause. A dermatologist can examine the affected area and determine whether the lumps are cysts, enlarged pores, abscesses, or another skin condition. Epidermoid cysts can often be permanently removed through a minor surgical procedure that removes the entire cyst wall. Infected abscesses may require professional drainage and, in some cases, antibiotics.

Some skin conditions can be successfully treated, while chronic inflammatory disorders may require ongoing medical care to control symptoms and prevent new lesions. The sooner the correct diagnosis is made, the easier it may be to prevent complications, discomfort, and additional scarring.

Most importantly, never squeeze, cut, or attempt to drain these lumps at home. Doing so can introduce bacteria, worsen inflammation, and cause permanent scarring. Anyone experiencing growing, painful, warm, or repeatedly draining lumps should consult a dermatologist. Fever or spreading redness may indicate a more serious infection requiring urgent medical attention.