Snapshot A 17-year-old male presents with lower back pain. He reports that the pain worsens when he sits or bends forward. Medical history is significant for metabolic syndrome. He is a high school student who spends hours playing online computer games. On physical exam, there is a tender and fluctuant mass that is erythematous. There is also purulent discharge from a sinus tract. Introduction Clinical definition skin and subcutaneous tissue infection occurring in the sacrococcygeal region leading to an acute or chronic abscess Epidemiology Incidence approximately 70,000 cases per year Demographics 15-30 years of age Location gluteal cleft Risk factors increased hair poor hygiene prolonged sitting skin pits trauma or irritation of the region obesity family history EitIoLOGY Pathophysiology pathoanatomy unclear possibly due to stretching the natal cleft which damages the hair follicles and creates a pore "pit" pore serves as an environment for hair to become embedded hair is drawn deeper into the pore, resulting in a foreign body reaction and creating a subcutaneous cavity Presentation Symptoms asymptomatic intergluteal region pain while the patient is sitting or partaking in activities that stretch the natal cleft (e.g., bending) swelling drainage that can be mucoid, bloody, or purulent fever malaise Physical exam pores found in the midline of the natal cleft painless sinus opening tender mass or sinus with fluid drainage mass may be fluctuant and erythematous Studies Diagnostic criteria clinical diagnosis Differential Perianal abscess Hidradenitis suppurativa Anorectal fistula Folliculitis Perianal furuncle and carbuncle Perianal complications from Crohn's disease Treatment Operative incision and drainage indication considered first-line for acute pilonidal cyst surgical excision of the sinus tract indication chronic or persistent pilonidal cyst Complications Cellulitis Abscess Squamous cell carcinoma this is rare Prognosis Approximately 50% of patients with acute pilonidal cyst may develop a chronic pilonidal cyst Approximately 20% of cases treated with initial surgery have recurrence of the disease