Endocervical adenocarcinomas usually demonstrate infiltrative and/or destructive invasion, and the depth and horizontal extent of the invasion are known to have prognostic utility. Here, we report the unusual case of a patient with endocervical adenocarcinoma showing intracystic papillary growth and discuss our methods for measuring and staging this lesion. A 45-yr-old Japanese woman (gravida, 0; para, 0) underwent a cone biopsy for squamous cell carcinoma in situ and atypical glandular cells. Macroscopically, an intracystic tumor (∼7.5 mm in diameter) was detected in the cervix. Microscopically, we observed both squamous cell carcinoma in situ and adenocarcinoma involving the squamo-columnar junction. Adenocarcinoma cells lining the nabothian cyst showed papillary proliferation and expansile stromal invasion without desmoplastic reaction. We evaluated this macroscopically and found that the visible papillary growth and expansile invasion deviated from the adenocarcinoma in situ; hence, we concluded that this lesion was an International Federation of Gynecology and Obstetrics stage IB1 adenocarcinoma. The patient underwent an abdominal radical hysterectomy, followed by bilateral salpingo-oophorectomy and pelvic lymph node dissection. No residual cervical cancer, other gynecologic malignancies, or lymph node metastases were observed. Further studies using cases with the same growth pattern are needed to determine whether our evaluation method is optimal for this type of lesion.