Version 2024

2024 ICD-10-CM Diagnosis Code C84.0

Mycosis fungoides

ICD-10-CM Code:
C84.0
ICD-10 Code for:
Mycosis fungoides
Is Billable?
Not Valid for Submission
Code Navigator:

Code Classification

  • Neoplasms
    (C00–D49)
    • Malignant neoplasms of lymphoid, hematopoietic and related tissue
      (C81-C96)
      • Mature T/NK-cell lymphomas
        (C84)

C84.0 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of mycosis fungoides. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Mycosis fungoides

Non-specific codes like C84.0 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for mycosis fungoides:

  • Use C84.00 for Mycosis fungoides, unspecified site - BILLABLE CODE

  • Use C84.01 for Mycosis fungoides, lymph nodes of head, face, and neck - BILLABLE CODE

  • Use C84.02 for Mycosis fungoides, intrathoracic lymph nodes - BILLABLE CODE

  • Use C84.03 for Mycosis fungoides, intra-abdominal lymph nodes - BILLABLE CODE

  • Use C84.04 for Mycosis fungoides, lymph nodes of axilla and upper limb - BILLABLE CODE

  • Use C84.05 for Mycosis fungoides, lymph nodes of inguinal region and lower limb - BILLABLE CODE

  • Use C84.06 for Mycosis fungoides, intrapelvic lymph nodes - BILLABLE CODE

  • Use C84.07 for Mycosis fungoides, spleen - BILLABLE CODE

  • Use C84.08 for Mycosis fungoides, lymph nodes of multiple sites - BILLABLE CODE

  • Use C84.09 for Mycosis fungoides, extranodal and solid organ sites - BILLABLE CODE

Clinical Information

  • Mycosis Fungoides

    a chronic, malignant t-cell lymphoma of the skin. in the late stages, the lymph nodes and viscera are affected.
  • Lymph Nodes

    they are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


Type 1 Excludes

Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • peripheral T-cell lymphoma, not elsewhere classified C84.4

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Patient Education


Lymphoma

Lymphoma is a cancer of a part of the immune system called the lymph system. There are many types of lymphoma. One type is Hodgkin disease. The rest are called non-Hodgkin lymphomas.

Non-Hodgkin lymphomas begin when a type of white blood cell, called a T cell or B cell, becomes abnormal. The cell divides again and again, making more and more abnormal cells. These abnormal cells can spread to almost any other part of the body. Most of the time, doctors don't know why a person gets non-Hodgkin lymphoma. You are at increased risk if you have a weakened immune system or have certain types of infections.

Non-Hodgkin lymphoma can cause many symptoms, such as :

  • Swollen, painless lymph nodes in the neck, armpits or groin
  • Unexplained weight loss
  • Fever
  • Soaking night sweats
  • Coughing, trouble breathing or chest pain
  • Weakness and tiredness that don't go away
  • Pain, swelling or a feeling of fullness in the abdomen

Your doctor will diagnose lymphoma with a physical exam, blood tests, a chest x-ray, and a biopsy. Treatments include chemotherapy, radiation therapy, targeted therapy, biological therapy, or therapy to remove proteins from the blood. Targeted therapy uses drugs or other substances that attack specific cancer cells with less harm to normal cells. Biologic therapy boosts your body's own ability to fight cancer. If you don't have symptoms, you may not need treatment right away. This is called watchful waiting.

NIH: National Cancer Institute


[Learn More in MedlinePlus]

Mycosis fungoides

Mycosis fungoides is the most common form of a type of blood cancer called cutaneous T-cell lymphoma. Cutaneous T-cell lymphomas occur when certain white blood cells, called T cells, become cancerous; these cancers characteristically affect the skin, causing different types of skin lesions. Although the skin is involved, the skin cells themselves are not cancerous. Mycosis fungoides usually occurs in adults over age 50, although affected children have been identified.

Mycosis fungoides may progress slowly through several stages, although not all people with the condition progress through all stages. Most affected individuals initially develop skin lesions called patches, which are flat, scaly, pink or red areas on the skin that can be itchy. Cancerous T cells, which cause the formation of patches, are found in these lesions. The skin cells themselves are not cancerous; the skin problems result when cancerous T cells move from the blood into the skin. Patches are most commonly found on the lower abdomen, upper thighs, buttocks, and breasts. They can disappear and reappear or remain stable over time. In some affected individuals, patches progress to plaques, the next stage of mycosis fungoides.

Plaques are raised lesions that are usually reddish, purplish, or brownish in color and itchy. Plaques commonly occur in the same body regions as patches. While some plaques arise from patches, others develop on their own, and an affected person can have both patches and plaques simultaneously. As with patches, cancerous T cells are found in plaques. Plaques can remain stable or can develop into tumors. Not everyone with patches or plaques develops tumors.

The tumors in mycosis fungoides, which are composed of cancerous T cells, are raised nodules that are thicker and deeper than plaques. They can arise from patches or plaques or occur on their own. Mycosis fungoides was so named because the tumors can resemble mushrooms, a type of fungus. Common locations for tumor development include the upper thighs and groin, breasts, armpits, and the crook of the elbow. Open sores may develop on the tumors, often leading to infection.

Although rare, the cancerous T cells can spread to other organs, including the lymph nodes, spleen, liver, and lungs. Spread to other organs can occur in any stage of mycosis fungoides but is most common in the tumor stage. In addition, affected individuals have an increased risk of developing another lymphoma or other type of cancer.


[Learn More in MedlinePlus]

Code History

  • 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.