2026 ICD-10-CM Diagnosis Code N64.4

Approximate Synonyms

The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.

Clinical Classification

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

Clinical Information

• Mastodynia

  pain in the breast generally classified as cyclical (associated with menstrual periods), or noncyclical, i.e. originating from the breast or nearby muscles or joints, ranging from minor discomfort to severely incapacitating.

MS-DRG Mapping for ICD-10-CM Code N64.4

Diagnosis-Related Groups (DRGs) are used to classify hospital cases for billing and healthcare management. They help standardize how hospitals and other providers are reimbursed for inpatient care. Patients are grouped based on their principal diagnosis into broader categories called Major Diagnostic Categories (MDCs).

Once assigned to a DRG, the hospital receives a set payment for the patient’s care, regardless of the actual services provided. This fixed rate is intended to cover the typical cost of treating patients within that group. The payment amount depends on the DRG's relative weight, which reflects the expected complexity and cost of care based on the severity of the patient’s condition.

Diagnostic related groups encourage healthcare providers to focus on quality and efficiency in patient care while managing costs effectively. The diagnosis code is present in the following groups for version MS-DRG V43.0 applicable from 10/01/2025 through 09/30/2026.

Convert N64.4 to ICD-9-CM

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

Patient Education

Breast Diseases

What are breast diseases?

Breast diseases include various conditions and changes in your breast. Most women experience breast changes at some time. Your age, hormone levels, and medicines you take may cause lumps, bumps, and discharges of fluids that are not breast milk.

Although many women fear cancer, most breast changes are benign, meaning they are not cancer. These breast changes are known as benign breast disease. See your health care provider if you have a breast lump, pain, discharge, or skin irritation. Minor and serious breast problems often have similar symptoms and may need treatment.

Common breast changes and conditions can include:

• Fibrocystic breast changes can include lumpiness, thickening, and swelling, often just before your period. Your breasts may feel painful, swollen, or tender.
• Cysts are fluid-filled lumps that may be tender.
• Fibroadenomas are solid, round, rubbery lumps that easily move when pushed, occurring most in younger women.
• Intraductal papillomas are wart-like benign tumors that grow in the milk duct of the breast.
• Blocked milk ducts.
• Milk production when you're not breastfeeding.

What are the symptoms of breast disease?

Symptoms depend on the type of breast disease. Benign breast diseases may not have any symptoms, or they could include:

• A lump or firm feeling in your breast or under your arm
• A change in the size or shape of your breast
• Nipple discharge
• Skin changes such as itching, redness or darkening, dimples, scaling, or puckering on your breast or nipple
• Painful, swollen, or tender breasts

See your provider if you're noticing any of these symptoms or other unusual changes. Some symptoms may be warning signs or symptoms of breast cancer.

How are breast diseases diagnosed?

Some breast changes may be felt or seen. You may notice a change in your breast, or your provider may notice it during a clinical breast exam. Other breast changes may only be found during a screening mammogram or other imaging tests such as an MRI or ultrasound. Your provider may also recommend a breast biopsy to check a suspicious change in your breast.

What are the treatments for breast disease?

Some benign breast changes may increase your risk of breast cancer in the future and may need treatment now. Treatment depends on the type of breast disease that you have. Some breast changes may go away without treatment, while others may require monitoring, biopsy, or surgery.

NIH: National Cancer Institute

[Learn More in MedlinePlus]

Code History

• FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026
• FY 2025 - No Change, effective from 10/1/2024 through 9/30/2025
• FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
• FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
• FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
• FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
• FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
• FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
• FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
• FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
• FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.