The risk of endometrial carcinoma is the highest with the following histological pattern of endometrial hyperplasia:

Ans is 'd' i.e. Complex hyperplasia with atypia The glandular hyperplasia of the endometrium are benign conditions that may produce symptoms clinically indistinguishable from early endometrial carcinoma.Because of their association with hyperestrogenic states, some of the hyperplasias even through reversible are considered premalignant lesions.Since both endometrial hyperplasia and endometrial carcinoma present clinically as abnormal bleeding, through endometerial sampling or fractional curettage is always necessary when hyperplasia is present to rule out coexisting carcinoma.Hyperplasia can be classified as simple and complex and with or without atypia.Hyperplasia without atypiaSimple hyperplasia without atypiaThe only feature is crowding of glands in the stroma. There is no nuclear atypia.It is asymptomatic and an incidental finding at hysterectomy, 1% of these cases progress to cancer whereas 80% spontaneously regress (when followed for 15 years)Complex hyperplasia without atypiaComplex crowded appearance of the gland without intervening stroma. There can be epithelial stratification and mitotic overcrowdingLeft untreated for 13 years complex hyperplasia regresses in 83% and progress to cancer in 3% cases Hyperplasia with atypiaSimple hyperplasia with atypia.Endometrial glands lined by enlarged cells Increased nuclear by cytoplasmic ratioIrregular nuclei with coarse chromatin clumping and prominent nucleoli Progression to carcinomas occur in 8%Complex hyperplasia with atypia - Progresses to cancer in 29%Progression of Hyperplasia to Cancer Hyperplasia without atypiaSimple - 1%Complex - 3%Hyperplasia with atypiaSimple - 8%Complex - 29%