C84.09
BillableMycosis fungoides, extranodal and solid organ sites
HCC Category Mapping
V28HCC 20 — Lung and Other Severe Cancers
0.000V24HCC 10 — Lymphoma and Other Cancers
0.675ESRDHCC 10 — Lymphoma and Other Cancers
0.000RxHCCHCC 19 — Lymphoma and Other Cancers
0.000What This Code Means
A type of skin cancer (mycosis fungoides) that has spread to organs or tissues outside the lymph node system.
Coding Tips
- •This code captures extranodal involvement; document which specific organs or tissues are affected
- •Distinguish from nodal involvement codes to ensure accurate staging and prognosis assessment
Clinical Significance
Mycosis fungoides with extranodal and solid organ involvement represents the most advanced form of cutaneous T-cell lymphoma with spread to visceral organs beyond the skin and lymph nodes. This may include liver, lung, bone marrow, or gastrointestinal involvement. Extranodal mycosis fungoides carries a very poor prognosis and often indicates large cell transformation requiring aggressive systemic therapy.
Documentation Requirements
- ✓Skin biopsy confirming mycosis fungoides
- ✓Documentation of specific extranodal organs involved
- ✓Imaging or biopsy confirming organ involvement
- ✓Assessment for large cell transformation
- ✓TNMB staging reflecting visceral involvement and treatment plan
Commonly Confused Codes
C84.08 — Mycosis fungoides, multiple sites: C84.08 is for multiple lymph node sites; C84.09 is for involvement of organs outside the lymph node systemC84.07 — Mycosis fungoides, spleen: Splenic involvement has its own code; use C84.09 for other extranodal organsC78-C79 series — Secondary malignant neoplasms: Do not use metastasis codes for mycosis fungoides organ involvement