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Serendipitous discovery in a fistula-in-ano
  1. Anisha M Fernandes,
  2. Sathish Narayanaswamy,
  3. Sanjay A Pai
  1. Pathology and Laboratory Medicne, Columbia Asia Referral Hospital Yeshwanthpur, Bangalore, Karnataka, India
  1. Correspondence to Dr Sanjay A Pai, Pathology and Laboratory Medicne, Columbia Asia Referral Hospital Yeshwanthpur, Bangalore, KA 560 055, India; sanjayapai{at}

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Clinical question

A woman in her early 30s presented with perianal purulent discharge. A rectal examination showed a high complex fistula-in-ano. A fistulotomy was performed wherein two fistulous tracts at the 4 o’clock and 8 o’clock position involving the external sphincter muscle were identified, and the granulation tissue was submitted for histopathological evaluation.

What is your diagnosis?

  1. A dense infiltrate of macrophages with an artefact amidst the granulation tissue.

  2. Macrophages exhibiting emperipolesis along with a cotton fibre adjacent to them.

  3. Macrophages exhibiting emperipolesis along with a parasite in the adjacent tissues.

  4. Macrophages exhibiting emperipolesis with a slender vegetable cell adjacent to them.


Amidst abundant granulation tissue, without eosinophils, were numerous multinucleated macrophages showing emperipolesis (figure 1). The engulfed cells were lymphocytes, plasma cells and occasional …

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  • Handling editor Iskander Chaudhry.

  • Contributors AMF identified the parasite. SN performed the surgery and provided clinical inputs. SAP performed the histopathological evaluation of the tissue.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.