ICD-10-CM > N00-N99 > N60-N65 > N60 > N60.1 N60.1 Diffuse cystic mastopathy Non-Billable/Non-Specific Applicable To Cystic breastFibrocystic disease of breast Type 1 Excludes diffuse cystic mastopathy with epithelial proliferation (N60.3-) Codes N60.11Diffuse cystic mastopathy of right breastN60.12Diffuse cystic mastopathy of left breastN60.19Diffuse cystic mastopathy of unspecified breast