Superficial spreading squamous cell carcinoma of the uterine cervix involving the endometrium: Report of two cases with emphasis on the likely molecular mechanism.

Squamous cell carcinoma (SCC) of the cervix generally invades directly into the uterine wall, but in rare cases it spreads superficially to the inner surface of the uterus, thereby replacing the endometrium. This type is called superficial spreading SCC. In the present study we report two cases of this unusual form of cervical SCC and discuss the possible molecular mechanism involved. Two females, aged 64 (case 1) and 59 (case 2) years old, presented with post-menopausal vaginal bleeding. Histopathological studies of the resected specimens revealed non-keratinizing SCC of the cervix (pTIIA1 in case 1 and pTIIB in case 2). A notable finding in the two tumors was that atypical squamous cells were extending and replacing the endometrium directly from the cervix. Glandular involvement of atrophic endometrial glands was observed, however no invasive growth was observed in the endometrium in either case. Immunohistochemical studies revealed that CD138 was strongly expressed in the carcinoma cells superficially spreading in the endometrium in the two cases. It has been reported that the loss of expression of CD138, a cell-surface heparan sulfate proteoglycan participating in cell-cell and cell-extracellular matrix interactions, is correlated with tumor invasion and progression to cervical SCC. Our present findings suggest that CD138 expression in carcinoma cells may participate in superficial spread by regulating cell-cell interactions.