Primary transitional cell carcinoma of the endometrium: a case report and review of the literature

Transitional cell carcinoma (TCC) of the endometrium is an extremely rare histologic subtype of endometrial carcinoma. While TCC is more frequently observed in the ovary, only a few cases have been documented in the cervix, fallopian tubes, adnexa, and endometrium. We describe the clinical presentation, diagnostic work-up, treatment, and histopathological features of a patient with pure high-grade endometrial TCC, followed by a focused review of previously published cases. A 70-year-old woman presented with an enlarging endometrial mass detected incidentally on imaging, despite two prior benign curettages. A total laparoscopic hysterectomy with bilateral salpingo-oophorectomy was performed. Histopathology revealed a pure high-grade TCC confined to the endometrium, without lymphovascular invasion or myometrial infiltration. The immunophenotype was CK7+, Vimentin+, CK HMW+, p16+, and CK20–, with a very high Ki-67 index (> 90%). Molecular classification (The Cancer Genome Atlas/ProMisE) could not be established due to unavailable p53 and mismatch repair testing. One-month follow-up showed no evidence of recurrence. Pure endometrial TCC is extremely rare. Although its morphology is high grade, early-stage disease without invasion may demonstrate favourable short-term outcomes. This case contributes a unique value because it shows a completely pure TCC pattern, absence of invasion, and early detection. Primary high-grade TCC of the endometrium represents a diagnostic and therapeutic challenge due to its rarity, aggressive histologic features, and lack of standardized treatment protocols. This unusual case underscores the importance of integrating histopathological and immunohistochemical findings for accurate diagnosis and guiding optimal patient management.