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Int J Clin Exp Pathol 2013;6(4):766-770

Case Report
Inverted variant of urothelial carcinoma of the urinary bladder: a report of three cases
and a proposal for a new clinicopathologic entity

Tadashi Terada

Departments of Pathology, Shizuoka City Shimizu Hospital, Shizuoka, Japan

Received September 22, 2012; Accepted January 23, 2013; Epub March 15, 2013; Published April 1, 2013

Abstract: Inverted urothelial carcinoma (UC) without papillary areas is very rare; only 31 cases of three papers have been reported. The author
herein reports three additional cases, and proposes the term “inverted variant” (IV) of UC. The materials were 3 cases of IV of UC, 5 cases of
inverted papilloma (IP), and two cases of nested variant (NV) of UC. The three cases of IV of UC consisted of 56-year-old woman, 63-year-old
man, and 78-year-old man. Presenting symptoms were hematuria in all cases. The cystoscopic findings were elevated tumors without
papillary proliferations in all cases. The treatment was transurethral tumor resection (TUR-BT) in all cases. The sizes was 0.6 cm, 0.5 cm, and
3 cm. Microscopically, IV of UC showed inverted growth of atypical cells without papillary proliferations. Compared to IP, the inverted growth
pattern was similar, but cytological atypia and thick trabeculae were noted in IV of UP while they were absent in IP. Compared to NV of UC, the
growth pattern is different; NV of UC showed nested and vague tubular pattern. The cellular atypia is more pronounced in IV of UC than NV of
UC. Immunohistochemically, p53 expression was seen in all the cases of IV of UC and in all the cases of NV of UC, while p53 expression was
negative in all the cases of IP. Ki-67 labeling index was 25, 30 and 40% in IV of UC, 15 and 30% in NV of UC, and 3, 5, 6, 7, 9% in IP. Invasive
features were seen in 1 case of IV of UC and 2 cases of NV of UC. In all cases of IV of UC, IP, and NV of UC, the TUR-BT, but one case of IV of
UC, showed no recurrence after TUR-BT, while one case of IV of UC showed a recurrence. In conclusion, the IV and UC were structurally and
cytologically very different from the NV of UC. The IV of UC was structurally similar to IP, but cellular atypia and thickened trabeculae were seen
in IV and UC. p53 expression and Ki-67 labeling status were entirely different between in IV of UC and IP. The author proposes the term of IV of
UC as a new clinicopathological entity. (IJCEP1209022).

Keywords: Urothelial carcinoma, inverted type, inverted papilloma, urinary bladder, immunohistochemistry

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku, Shi-
zuoka 424-8636, Japan. Tel: +81-54-336-1111; Fax: +81-54-334-1173; E-mail: piyo0111jp@yahoo.co.jp