Drug-Induced Thrombotic Microangiopathy Arising During the Treatment of Anal Carcinoma After the Use of Mitomycin C

Abstract

Anal cancer is a rare disease where malignant cells originate in the tissues of the anal canal. This form of cancer is classically treated with a combination of radiation therapy and a chemotherapy regimen that includes mitomycin C. This case illustrates an unusual presentation of thrombotic microangiopathy associated with mitomycin C. A 57-year-old woman with a history of anal carcinoma treated with capecitabine/mitomycin C and radiation was sent to the emergency department by her oncologist for an incidental finding of worsening kidney function noted on a complete metabolic panel done prior to getting radiographic imaging. The patient was admitted to the hospital for suspected acute kidney injury from suspected ureteral obstruction and stent occlusion; however, despite reversal of the stents, renal function did not improve. Renal biopsy confirmed thrombotic microangiopathy and diagnosis of drug-induced thrombotic microangiopathy. This case discusses a side effect of thrombotic microangiopathy from mitomycin C and successful treatment with eculizumab.

Keywords: anal cancer; capecitabine; drug-induced thrombotic microangiopathy; mitomycin; mitomycin c (mmc).

Figure 1. CT abdomen and pelvis show bilateral hydroureteronephrosis (yellow arrows).

Figure 2. Immunohistological stains of renal biopsy: A: A glomerulus showing RBC congestion and the afferent arteriole contains a fibrin thrombus (arrow) (Jones Methenamine stain, original magnification 60X). B: A glomerulus shows RBC congestion and fibrin thrombus (arrow) (Periodic acid-Schiff stain, original magnification 60x). C: A glomerulus shows global attenuation of capillary lumina and fibrin thrombus (arrow) in the hilar region (Trichrome stain, original magnification 60x). D: Patchy interstitial edema and inflammation are seen. Proximal tubules show simplification and loss of apical brush border (acute tubular injury) (Courtesy of Dr. Stokes at Columbia University, permission was obtained prior to inclusion).