May 2023 – Gastroenterology Pathology

A 70-year-old woman has a chief complaint of melena. She has a past medical history of chronic lymphocytic leukemia and metastatic breast cancer. Her breast cancer is currently being treated with paclitaxel and pembrolizumab. She undergoes colonoscopy, which is essentially normal. Biopsies of the colon show colonic mucosa with marked crypt apoptosis. The findings are suggestive of drug injury. This pattern is described in immune checkpoint inhibitor associated colitis.

Figure 1

Which of the following is associated with a pattern of injury showing ringed mitoses?

  • Pembrolizumab
  • Mycophenolate mofetil
  • Graft-versus-host disease
  • Paclitaxel

The correct answer is ...


In addition to pembrolizumab, the patient was treated with paclitaxel, which can show a pattern of injury of ringed mitoses. The other answer choices all can show an apoptotic colopathy picture of injury.


  1. Montgomery EA. Biopsy Interpretation of the Gastrointestinal Tract Mucosa. Lippincott Williams & Wilkins; 2006.
Photo of Rosalie Sterner, MD, PhD

Rosalie Sterner, M.D., Ph.D.

Resident, Anatomic & Clinical Pathology
Mayo Clinic

Photo of Christopher Hartley, M.D.

Christopher (Chris) Hartley, M.D.

Consultant, Anatomic Pathology
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science

MCL Education

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