What is the diagnosis for bulging dark blue or purple anal tissue associated with acute anal pain?

The diagnosis associated with bulging dark blue or purple anal tissue that is linked with acute anal pain is a thrombosed external hemorrhoid. This condition occurs when the veins in the external hemorrhoidal plexus become engorged with blood and subsequently clot, leading to increased pressure, swelling, and characteristic discoloration—often appearing dark blue or purple. The acute pain stems from inflammation and thrombosis within the hemorrhoid.

A key factor distinguishing this condition is the presentation of the hemorrhoid itself, which can be palpated externally and typically appears as a swollen, tender mass near the anal verge. The acute onset of pain is often a result of rapid engorgement and the pressure from the clot formation.

In contrast, an anal fissure generally manifests as sharp pain during bowel movements and may be associated with a linear tear in the anal mucosa, often accompanied by bleeding, but does not present as a bulging mass. An anal abscess involves localized infection leading to pus formation and can cause a throbbing pain, but it usually presents with systemic symptoms like fever and doesn't have the characteristic coloration like a thrombosed hemorrhoid. A pilonidal cyst is a different entity entirely, typically located in the sacrococcygeal area