A case of uterine adenomyoma of endocervical type that was suspected as minimal deviation adenocarcinoma on biopsy, MRI findings, and literature review.

Uterine adenomyomas of endocervical type are rare benign tumors of the uterine cervix commonly presented as cyst-like, dilated glandular structures within polypoid masses. A premenopausal woman in her 50s was referred to our hospital because of an increasing watery vaginal discharge. A multifocal cyst measuring 5 × 4.5 cm in size projecting into the endocervical canal was revealed on a contrast-enhanced MRI. The fluid within the tumor showed a hypointense signal on T1-weighted imaging (T1WI) and a hyperintense signal on T2-weighted imaging (T2WI). On T2WI, most of the septa within the tumor showed a slightly hyperintense to hypointense signal, whereas some areas revealed a strong hypointense signal; the contrast effect on the septum was satisfactory. On the T2WI taken 2 years previously, the tumor was a 4.5 × 3.5 cm polypoid mass protruding from the posterior endocervical wall. Contrastingly, the current T2WI showed that the stem was no longer identifiable because of tumor growth. Because previous imaging showed that the tumor was a stalked tumor protruding from the posterior endocervical wall, the imaging diagnosis was uterine adenomyoma of the endocervical type. A biopsy suggested the possibility of a minimal deviation adenocarcinoma (MDA). Hence, a total hysterectomy was performed. The final diagnosis confirmed the uterine adenomyoma of endocervical type. Uterine adenomyoma of the endocervical type might be difficult to differentiate from MDA in small biopsy specimens; therefore, evaluation of morphology by MRI is considered important in preoperative diagnosis.