ER-positive endocervical adenocarcinoma mimicking endometrioid adenocarcinoma in morphology and immunohistochemical profile: A case report of application of HPV RNAscope detection

RATIONALE: Usual-type endocervical adenocarcinoma (ECA), high-risk HPV associated, is the most common type of glandular carcinoma in the endocervix. Mucin-depleted usual-type ECA is 1 end of morphological lineage of usual-type ECA and morphologically may show endometrioid features, which could cause diagnostic challenge with uterine endometrioid adenocarcinoma (EEC) and primary endometrioid ECA, especially in the setting of small biopsy and endocervical curettage (ECC). PATIENT CONCERNS: A 37-year-old women presented with dyspareunia for 1 year, showing atypical glandular cell on a liquid-based Pap TCT examination and positive for HPV16 detection. ECC showed EEC in another hospital based on its “endometrioid” morphology and immunohistochemical profiles (ER/PR/PAX8 strongly positive, though p16 also strongly positive). DIAGNOSES: The specimen of hysterectomy in our hospital displayed a lesion confined to the uterine cervix showing the same morphology and immunohistochemical profiles as ECC. Finally, we successfully performed HPV RNAscope and detected high-risk human papilloma virus (HPV) E6/E7 mRNA particles in tumor cells in situ, which warranted usual-type ECA with mucin-depleted feature, a rare deviation of usual-type of ECA. INTERVENTIONS: The patient underwent total hysterectomy with lymph node dissection. OUTCOMES: To date, 14 months after surgery, the patient is well without recurrence or distant metastasis, and undergoes regular reexamination. LESSONS SUBSECTIONS: We report a rare case of mucin-depleted usual-type ECA showing overlapping morphological and immunohistochemical profiles with EEC. The pathological diagnosis was confirmed by high-risk HPV RNAscope detection which is superior than immunohistochemistry to identify usual-type ECA, warranting an important role in assisting the diagnosis of morphological vague cases.