Differential Diagnosis for Perianal Discharge with History of Abscesses

• Single Most Likely Diagnosis
  • A. Perianal fistula: The history of recurrent perianal abscesses and the presence of a cord-like structure on digital rectal examination (DRE), along with an internal opening at the dentate line seen on proctoscopy, strongly suggests a perianal fistula. The absence of swelling, fever, or leucocytosis indicates a chronic, rather than acute, condition.
• Other Likely Diagnoses
  • C. Intersphincteric fistula: Given the internal opening at the dentate line and the history of abscesses, an intersphincteric fistula is a plausible diagnosis. This type of fistula is the most common and typically has an internal opening at the dentate line, which matches the patient's presentation.
• Do Not Miss Diagnoses
  • D. Supralevator abscess: Although less likely given the absence of fever, leucocytosis, or swelling, a supralevator abscess could potentially present with a fistula or discharge if it has drained or is partially drained. Missing this diagnosis could lead to severe complications, including sepsis.
• Rare Diagnoses
  • B. Ischiorectal fistula: This is less common and typically involves a more complex tract that may not directly connect to the dentate line. The presentation might not fully align with the patient's symptoms, especially the specific location of the internal opening and the nature of the discharge. However, it remains a consideration in the differential diagnosis due to the history of abscesses and the possibility of an atypical presentation.