Differential Diagnosis for Perianal Discharge with History of Abscesses

• Single Most Likely Diagnosis
  • A. Perianal Fistula: This is the most likely diagnosis given the history of recurrent perianal abscesses and the presence of a cord-like structure on digital rectal examination (DRE) and an internal opening at the dentate line on proctoscopy. The absence of swelling, fever, or leucocytosis suggests a chronic condition rather than an acute infection.
• Other Likely Diagnoses
  • C. Intersphincteric Fistula: This type of fistula is a common complication of perianal abscesses and could explain the findings, especially the internal opening at the dentate line. The lack of symptoms like swelling or fever does not rule out this diagnosis.
• Do Not Miss Diagnoses
  • D. Supralevator Abscess: Although less likely given the absence of fever or leucocytosis, a supralevator abscess could potentially cause a fistula and should be considered due to its potential for serious complications if missed.
• Rare Diagnoses
  • B. Ischiorectal Fistula: This is less common and typically would present with more significant symptoms due to its location. However, it remains a possibility, especially if the fistula tract extends into the ischiorectal fossa.

The justification for these categorizations is based on the clinical presentation and the typical progression of perianal diseases. The history of recurrent abscesses and the specific findings on DRE and proctoscopy guide the differential diagnosis towards conditions that are known complications of such a history. The absence of acute inflammatory signs helps to differentiate between acute and chronic conditions.