2024 ICD-10-CM Diagnosis Code B27.9

Infectious mononucleosis, unspecified

• B27.9 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
• The 2024 edition of ICD-10-CM B27.9 became effective on October 1, 2023.
• This is the American ICD-10-CM version of B27.9 – other international versions of ICD-10 B27.9 may differ.

The following code(s) above B27.9 contain annotation back-references

 that may be applicable to B27.9:

• A00-B99  Certain infectious and parasitic diseases
• B27  Infectious mononucleosis

Clinical Information

• A common, acute infection usually caused by the epstein-barr virus (herpesvirus 4, human). There is an increase in mononuclear white blood cells and other atypical lymphocytes, generalized lymphadenopathy, splenomegaly, and occasionally hepatomegaly with hepatitis.
• Acute disease characterized by fever and swollen lymph nodes and an abnormal increase of mononuclear leucocytes or monocytes in the bloodstream; not highly contagious; some believe it can be transmitted by kissing.
• Infectious mononucleosis, or “mono”, is an infection caused by the epstein-barr virus. The virus spreads through saliva, which is why it’s sometimes called “kissing disease.” mono occurs most often in 15 to 17-year-olds. However, you can get it at any age. Symptoms of mono include
  • fever
  • sore throat
  • swollen lymph glands
  sometimes you may also have a swollen spleen. Serious problems are rare. A blood test can show if you have mono. Most people get better in two to four weeks. However, you may feel tired for a few months afterward. Treatment focuses on helping symptoms and includes medicines for pain and fever, warm salt water gargles and plenty of rest and fluids.

Code History

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change
• 2024 (effective 10/1/2023): No change

Code annotations containing back-references to B27.9:

• Code First: K77
• Type 1 Excludes: G63