Peristomal Pagetoid Spread of Urothelial Carcinoma of the Ureter
The patient was a 69-year-old female who developed macroscopic hematuria 7 years ago. Under clinical diagnosis of bladder carcinoma, she underwent transurethral resection, with a resultant pathological diagnosis of urothelial carcinoma in situ (CIS). Two years later, she developed recurrence of stage Tis UC in the most distal part of the left ureter and underwent left nephroureterectomy. One year later, she had intravesical recurrence of UC as stage Tis disease with resistance to BCG therapy and underwent radical cystectomy and reconstruction with ureterocutaneostomy. Two years ago, peristomal inflammation developed and persisted despite regular medication for dermatitis.\nTwo dermatologists (S.I. and M.T.) suspected squamous cell carcinoma or metastatic skin carcinoma by inspection and performed peristomal skin biopsy. Under a diagnosis of a peristomal Paget phenomenon of UC, we performed en-bloc resection of the remaining ureter and peristomal skin with a sufficient normal margin () and percutaneous nephrostomy, followed by reconstruction of the abdominal wall to wrap the exposed fascia with surrounding excess skin.\nPagetoid cells and conventional CIS cells were observed by light microscopy in the distal two-thirds of the right ureter. The pagetoid cells formed a cluster and had spread to basal layers of transitional epithelium with partial squamous metaplasia. These cells were characterized by abundant clear cytoplasm with occasional vacuoles, enlarged hyperchromatic nuclei and overt nucleoli. Pagetoid cells had also spread into the peristomal epidermis directly from the ureteral mucosa () and were present among p63-positive cells (i.e. epidermal basal cells), which showed that pagetoid cells had spread to the basal layer of the epidermis. However, the basal membrane between the epidermis and dermis was intact and the tumor cells had not invaded the dermis. The intraepidermal pagetoid cells had abundant mitoses and formed a papillary or pseudoalveolar architecture. The surrounding stroma showed prominent congestion and infiltration of lymphocytes and histiocytes, but neither via-vessel extension nor direct invasion of neoplastic cells (). In immunohistochemistry, the cells in the epidermis and ureteral mucosa were positive for CK7 and CK20 () and pagetoid cells were positive for HER2 (). In contrast to the distal region, the proximal surgical end of the ureter was free of cancerous cells.