Cervical adenoid basal tumors comprised of adenoid basal epithelioma associated with various types of invasive carcinoma: Clinicopathologic features, human papillomavirus DNA detection, and P16 expression

Abstract

Adenoid basal tumors are uncommon cervical lesions that some pathologists consider invasive carcinomas but others consider "epitheliomas" due to their low-grade histological appearance and rarely documented malignant behavior. We report the clinicopathologic features of 10 tumors comprised of both typical low-grade adenoid basal tumors (epitheliomas) intimately associated with invasive carcinomas having infiltrative growth, increased cytological atypia and mitotic activity, and various types of differentiation, including adenoid basal/squamous, pure squamous, adenoid cystic, and small cell neuroendocrine. Tumors were evaluated for the presence of human papillomavirus (HPV) DNA and immunohistochemical p16 expression. The patients in the study group ranged in age from 45 to 81 years (mean, 65 years). Most of the patients presented with abnormal cervicovaginal smears. The initial diagnosis was made on specimens obtained by cervical biopsy, laser electrocautery excision procedure (LEEP), or cone biopsy in 8 patients. Two 2 patients were incidentally diagnosed in hysterectomy specimens. All 10 patients had squamous intraepithelial lesions (9 high-grade, 1 low-grade). In all cases diagnosed in LEEP or cone biopsy specimens, the invasive carcinoma component was present in the excisional specimen and extended to the margins. Seven patients diagnosed on excisional or biopsy specimens who underwent hysterectomy had residual tumor in the cervix, ranging from microscopic foci to deeply invasive. No lymph node metastases were identified in 4 patients who were staged. Seven patients with follow-up were alive without evidence of disease after follow-up intervals of 8 to 84 months (mean, 45 months; median, 29 months). One patient with a component of small cell carcinoma died of other causes without evidence of disease at 18 months. HPV 16 DNA was detected in both the adenoid basal epithelioma and invasive carcinoma components in 9 tumors by in situ hybridization, and HPV 33 was detected by polymerase chain reaction in 1 tumor. All tumors expressed p16 diffusely. Adenoid basal tumors are high-risk HPV-related tumors that can be comprised of both a low-grade adenoid basal tumor, which can be designated as epithelioma, and invasive carcinomas of various types. The invasive component is usually evident in the excisional biopsy specimen, allowing for recognition of a tumor that needs further management.