. Author manuscript; available in PMC: 2017 Apr 1.

Published in final edited form as: Gynecol Oncol. 2016 Apr;141(1):36–42. doi: 10.1016/j.ygyno.2016.02.028

Table 1.

New risk stratification system for invasive endocervical adenocarcinomas based on pattern of invasion (Silva system).

	Silva system
Pattern A	Well-demarcated glands with rounded contours, usually forming groups No destructive stromal invasion No single cells or cell detachment No lymphovascular invasion Complex intraglandular growth acceptable (cribriform, papillae) Lack of solid growth (well-moderately differentiated) Irrelevant depth of the tumor or relationship to large cervical vessels
Pattern B	Localized (limited, early) destructive stromal invasion arising from pattern A glands (well-demarcated glands) Individual or small groups of tumor cells, separated from pattern A-type glands, frequently in desmoplastic or inflamed stroma Single, multiple, or linear foci at base of tumor Lymphovascular invasion (present/absent) Lack of solid growth (well-moderately differentiated)
Pattern C	Diffuse destructive stromal invasion, characterized by: Diffusely infiltrative glands, with associated extensive desmoplastic response Glands often angulated or with canalicular pattern, with interspersed open glands Confluent growth filling a 4x field (5 mm): glands, papillae (stroma only within papillae), or mucin lakes Solid, poorly differentiated component (architecturally high grade); nuclear grade is disregarded Lymphovascular invasion (present/absent)

Adapted from Roma AA, et al. Am J Surg Pathol. 2015 May;39(5):667–72.