Medical Term for a Cyst on the Buttocks
A cyst located in the natal cleft (the groove between the buttocks) is called a pilonidal cyst or pilonidal sinus disease. 1, 2
Definition and Location
Pilonidal cyst disease is an acquired inflammatory condition that predominantly affects the natal cleft of the buttocks. 3 The term "pilonidal" literally refers to a nest of hair, and these cysts characteristically occur in the sacrococcygeal region—the area at the base of the spine where the buttocks meet. 2, 4
Key Distinguishing Features
The location is critical for proper identification:
- Pilonidal cysts are located in the natal cleft (the groove between the buttocks), typically in the sacrococcygeal region 2, 3
- These should be distinguished from simple sacral dimples, which have different clinical significance based on their exact location 5
- The disease predominantly affects young men, with a male-to-female ratio of 3-4:1, typically presenting toward the end of the second decade of life 3
Clinical Presentation
Pilonidal cysts present along a spectrum:
- Initially asymptomatic pits or small midline openings 2
- May progress to painful, draining lesions when complications like abscess formation develop 3
- Additional lateral sinus openings are frequently present 2
- The sinus is initiated from a small midline opening lined by stratified squamous epithelium 2
Important Differential Considerations
When evaluating a cyst in the buttock region, consider these alternatives in your differential diagnosis:
- Recurrent cutaneous abscesses, hidradenitis suppurativa, folliculitis, furuncles, and perianal fistulas 1
- Sacral dimples (coccygeal vs. lumbosacral)—these require different management 5
- Dermoid cysts or subcutaneous masses associated with dermal sinus tracts 6, 5
Common Pitfall to Avoid
Do not confuse benign coccygeal dimples (located below an imaginary line connecting the tops of the gluteal cleft) with pathologic lumbosacral dermal sinus tracts (located above this line on the flat part of the sacrum). 5 While pilonidal cysts occur in the natal cleft itself, lumbosacral dermal sinus tracts are located higher on the sacrum and require immediate neurosurgical referral due to risk of CNS infection and other serious complications. 6, 5