22-year-old male presents with worsening pain at the top of…
22-year-old male presents with worsening pain at the top of his buttocks for the past 4 days. He reports increasing discomfort when sitting and driving. He denies rectal bleeding, constipation, or pain with defecation. He has had similar episodes in the past that resolved spontaneously. He works as a delivery driver and sits for prolonged periods. On examination, there is a 3-cm erythematous, fluctuant, tender mass located in the midline of the natal cleft approximately 4 cm superior to the anus. A small midline pit with surrounding hair is noted. Rectal exam is normal and nontender. Which of the following is the most likely diagnosis?