Pilonidal Cyst vs Abscess vs Sinus: What’s the Difference?
Pilonidal cyst is the accumulation of hair shafts, lint and debris within a defunctionalized hair follicle within the midline crease skin. The hair enters via the “midline pit”, the orifice at the epidermal level which is grossly visible as a dilated pore.
A pilonidal abscess is a pilonidal cyst which has become “infected”, ie the immune system has mounted an inflammatory response to the bacteria present on the embedded hair shafts. This immune response is represented by the presence of pus, which causes redness,swelling and great pain. The onset of abscess is when most patients are driven to seek medical attention.
What is a pilonidal sinus? When drainage of a pilonidal abscess is not achieved, the body may build a channel from the abscess cavity to the skin, to basically effect this drainage. To this end, the external opening of this sinus “tract” will drain this pus-like fluid on a constant or intermittent basis. Of note, the tract often develops along the path of least resistance, for example, along a surgical scar. This is why we see predictable sinus tracts in Limberg flap scars. The external opening is also often not in the midline, but instead to the side. This tract and opening may be long and complex, the one situation in which an aggressive excision is warranted.
Why does this distinction matter?
The presence of a non infected pilonidal cyst is, in our opinion at PTCNJ, not an indication for cleft-lift. It is more appropriately an indication for minimally invasive treatment.
Repeat abscesses, however, seem a more appropriate case for the reliably curative cleft-lift.
Pilonidal sinus must be considered on a case-by-case basis. While a simple, short, sinus may be quite amenable to a minimally invasive approach, the case of a long complex, sinus tract warrants cleft-lift.
