Classification according to Prechtel
| Degree according to Prechtel | Histology | Frequency in % | Risk of carcinoma |
| Simple mastopathy (grade I) | Simple mastopathy: nonproliferative lesions. | 70 % | not increased |
| Simple proliferative mastopathy (grade II) | Proliferative lesions without atypia: simple proliferative mastopathy such as adenosis, epitheliosis, papillomatosis | 20 % | 1.3 to 2-fold increased |
| Atypical proliferating mastopathy (grade III)* . | Ductal or lobular atypical hyperplasia* * : atypical proliferating mastopathy with atypical epithelial proliferations | 10 % | approx. 5-fold increase* |
* Thus, in the case of an atypical form, one in ten women with evidence of atypical hyperplasia will develop breast carcinoma within ten years of definitive diagnosis. Atypical hyperplasia is therefore considered a precancerous condition (precancer).
* * atypical hyperplasia of the lobules (synonyms: atypical ductal hyperplasia, abbreviation: ADH) According to a cohort study, the ten-year risk of invasive breast carcinoma (breast cancer) following the diagnosis of atypical ductal hyperplasia is overestimated. The cumulative risk of invasive breast carcinoma was 2.6-fold higher than in women without ADH at baseline (95% confidence interval between 2.0 and 3.4). Note: The transition of atypical hyperplasia to true in situ carcinomas (lobular and ductal carcinoma in situ; DCIS and LCIS) is smooth.