Primary squamous cell carcinoma of the endometrium unrelated to human papilloma virus: a molecular study

Molecular Analysis of HPV-independent Primary Endometrial Squamous Cell Carcinoma Reveals TP53 and CDKN2A Comutations : A Clinicopathologic Analysis With Re-evaluation of Diagnostic Criteria

Human papillomavirus (HPV)-independent primary endometrial squamous cell carcinoma (PESCC) is a rare but aggressive subtype of endometrial carcinoma for which little is known about the genomic characteristics. Traditional criteria have restricted the diagnosis of PESCC to cases without any cervical involvement. However, given that modern ancillary techniques can detect HPV and characteristic genetic alterations that should identify the more common mimics in the differential diagnosis, including endometrial endometrioid carcinoma with extensive squamous differentiation and HPV-associated primary cervical squamous cell carcinoma, those criteria may benefit from revision. To further characterize PESCC, we identified 5 cases of pure squamous cell carcinoma dominantly involving the endometrium that had the potential to be PESCC: 1 case involving only the endometrium and 4 cases with some involvement of the cervix. Clinicopathologic features were assessed and immunohistochemical analysis (p16, estrogen receptor, progesterone receptor, and p53), HPV RNA in situ hybridization (high-risk and low-risk cocktails and targeted probes for 16 and 18), and molecular studies were performed. All tumors showed aberrant/mutation-type p53 expression, were negative for estrogen receptor, progesterone receptor, and p16, and had no detectable HPV. Per whole-exome sequencing, 4 of the 5 tumors demonstrated comutations in TP53 and CDKN2A (p16). Four patients died of disease within 20 months (range, 1 to 20 mo; mean, 9 mo), and 1 patient had no evidence of disease at 38 months. PESCC represents a unique, clinically aggressive subtype of endometrial cancer with TP53 and CDKN2A comutations. This characteristic profile, which is similar to HPV-independent squamous cell carcinoma of the vulva, is distinct from endometrioid carcinoma with extensive squamous differentiation and HPV-associated primary cervical squamous cell carcinoma and can be used to distinguish PESCC from those mimics even when cervical involvement is present. Diagnostic criteria for PESCC should be relaxed to allow for cervical involvement when other pathologic features are consistent with, and ancillary techniques are supportive of classification as such.

Primary squamous cell carcinoma of the endometrium in a woman of reproductive age: a rare case report

Primary endometrial squamous cell carcinoma is an extremely rare tumor that tends to occur in postmenopausal women. We report on a 33-year-old woman who presented with a history of irregular vaginal bleeding for more than 2 years, and a vaginal mass for more than 1 month. Biopsy of the vaginal mass revealed an invasive poorly differentiated squamous cell carcinoma. The patient underwent radical hysterectomy, bilateral salpingo-oophorectomy, omentectomy, pelvic lymph node dissection, peritoneal sampling and vaginal tumor resection. On the basis of her medical history, auxiliary examination and postoperative pathology, the patient was diagnosed with stage IV endometrial squamous cell carcinoma. The patient was followed-up regularly and remained in good condition.

[Surprise in abrasion diagnostics]

Typical localizations of gynecological squamous cell carcinomas are the cervix, vulva and vagina and are therefore not uncommonly diagnosed in curettages. A differentiation from reactive hyperplastic alterations with a possible invasiveness in samples taken from the surface of the special type of well-differentiated verrucous squamous cell carcinoma can be difficult. This pitfall of such a tumor is presented in the case described here with corresponding diagnostic difficulties.