Purpose: In this manuscript, we have demonstrated a case of old man with urothelial cell carcinoma under treatment of pembrolizumab showing skin rash and no residual tumor was identified in the follow up.

 

Case reports: A 91 year old man was presented to Tri Service General Hospital with painless gross hematuria for days. Magnetic resonance imaging (MRI) of abdomen demonstrated right side mild hydroureteronephrosis with obstructive level at lower third of the ureter and dilated upper calyces with irregular wall thickening. Ureterorenoscopy (URS) revealed a right upper third ureteral tumor and a right renal pelvis tumor. Right side renal pelvis tumor was biopsied and the pathology revealed high grade urothelial dysplasia. The patient received hand-assisted retroperitoneoscopic nephroureterectomy and removal of right bladder cuff. Final pathology proved invasive papillary urothelial cell carcinoma with invasion to renal parenchyma, pT3N0M0, stage III. On abdominal sonography follow up, a hyperechoic lesion, 1.4 x 0.9-cm in size was noted in the lateral wall of urinary bladder. Subsequent abdominal MRI showed a 1cm size small nodule over the left renal lower calyx. Highly invasive papillary urothelial cell carcinoma with metastasis to left side kidney was impressed and immune checkpoint inhibitor (ICI) Keytruda (pembrolizumab) was prescribed. On the third dose of the ICI, skin itchy with skin rash was observed and glucocorticoid was administered. The skin lesions subsided few days later. In the same week follow up of abdominal computed tomography (CT) scan, there were no evidence of lesions on the left side kidney.

 

Conclusions: As far as we know, our case is the first in showing nonspecific skin rash after the treatment of pembrolizumab for metastatic urothelial cell carcinoma. After the presence of these dermatological side effects, no residual tumor was identified in the follow up examination. To our knowledge, it has not been mentioned in the previous literature, we hypothesize it maybe a sign of overactivation of self immunity against tumor cells, which predicts better outcome