C84.91 is the authoritative medical code for Mature T/NK-cell lymphomas, unspecified, lymph nodes of head, face, and neck. This classification is used in medical billing and clinical recording to specify the clinical criteria for mature t/nk-cell lymphomas, unspecified, lymph nodes of head, face, and neck (ICD-10-CM C84.91), ensuring healthcare documentation aligns with 2026 federal coding standards.
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Official Registry Overview & Definition
Mature T/NK-cell lymphomas, unspecified, lymph nodes of head, face, and neck is a billable ICD-10-CM diagnosis code C84.91. Excludes1 (not coded here): mature T-cell lymphoma, not elsewhere classified C84.4-; personal history of non-Hodgkin lymphoma Z85.72. Excludes2 (not included here): Kaposi's sarcoma of lymph nodes C46.3; secondary and unspecified neoplasm of lymph nodes C77.-; secondary neoplasm of bone marrow C79.52; secondary neoplasm of spleen C78.89.
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for C84.91 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- mature T-cell lymphoma, not elsewhere classified C84.4-
- personal history of non-Hodgkin lymphoma Z85.72
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- Kaposi's sarcoma of lymph nodes C46.3
- secondary and unspecified neoplasm of lymph nodes C77.-
- secondary neoplasm of bone marrow C79.52
- secondary neoplasm of spleen C78.89
Frequently Asked Questions (FAQ) & Clinical Guidance
What can't be coded together with C84.91?
Per Excludes1 instructions, C84.91 must not be reported with: mature T-cell lymphoma, not elsewhere classified (C84.4-); personal history of non-Hodgkin lymphoma (Z85.72).
Can C84.91 be reported alongside related conditions?
Per Excludes2 instructions, C84.91 and the following may both be reported when both are present: Kaposi's sarcoma of lymph nodes (C46.3); secondary and unspecified neoplasm of lymph nodes (C77.-); secondary neoplasm of bone marrow (C79.52); secondary neoplasm of spleen (C78.89).
Codes in This Family (40)
Official ICD-10-CM classifications in the same code family as C84.91, with their registry titles.
- C84 — Mature T/NK-cell lymphomas
- C84.0 — Mycosis fungoides
- C84.00 — Mycosis fungoides, unspecified site
- C84.01 — Mycosis fungoides, lymph nodes of head, face, and neck
- C84.02 — Mycosis fungoides, intrathoracic lymph nodes
- C84.03 — Mycosis fungoides, intra-abdominal lymph nodes
- C84.04 — Mycosis fungoides, lymph nodes of axilla and upper limb
- C84.05 — Mycosis fungoides, lymph nodes of inguinal region and lower limb
- C84.06 — Mycosis fungoides, intrapelvic lymph nodes
- C84.07 — Mycosis fungoides, spleen
- C84.08 — Mycosis fungoides, lymph nodes of multiple sites
- C84.09 — Mycosis fungoides, extranodal and solid organ sites
- C84.0A — Mycosis fungoides, in remission
- C84.1 — Sézary disease
- C84.10 — Sézary disease, unspecified site
- C84.11 — Sézary disease, lymph nodes of head, face, and neck
- C84.12 — Sézary disease, intrathoracic lymph nodes
- C84.13 — Sézary disease, intra-abdominal lymph nodes
- C84.14 — Sézary disease, lymph nodes of axilla and upper limb
- C84.15 — Sézary disease, lymph nodes of inguinal region and lower limb
- C84.16 — Sézary disease, intrapelvic lymph nodes
- C84.17 — Sézary disease, spleen
- C84.18 — Sézary disease, lymph nodes of multiple sites
- C84.19 — Sézary disease, extranodal and solid organ sites
- C84.1A — Sézary disease, in remission
- C84.4 — Peripheral T-cell lymphoma, not elsewhere classified
- C84.40 — Peripheral T-cell lymphoma, not elsewhere classified, unspecified site
- C84.41 — Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of head, face, and neck
- C84.42 — Peripheral T-cell lymphoma, not elsewhere classified, intrathoracic lymph nodes
- C84.43 — Peripheral T-cell lymphoma, not elsewhere classified, intra-abdominal lymph nodes
- C84.44 — Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of axilla and upper limb
- C84.45 — Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of inguinal region and lower limb
- C84.46 — Peripheral T-cell lymphoma, not elsewhere classified, intrapelvic lymph nodes
- C84.47 — Peripheral T-cell lymphoma, not elsewhere classified, spleen
- C84.48 — Peripheral T-cell lymphoma, not elsewhere classified, lymph nodes of multiple sites
- C84.49 — Peripheral T-cell lymphoma, not elsewhere classified, extranodal and solid organ sites
- C84.4A — Peripheral T-cell lymphoma, not elsewhere classified, in remission
- C84.6 — Anaplastic large cell lymphoma, ALK-positive
- C84.60 — Anaplastic large cell lymphoma, ALK-positive, unspecified site
- C84.61 — Anaplastic large cell lymphoma, ALK-positive, lymph nodes of head, face, and neck
Related Codes & Numerical Sequence (Crawl Map)
Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures:
ICD Code C81.91
Hodgkin lymphoma, unspecified, lymph nodes of head, face, and neck
ICD Code C82.91
Follicular lymphoma, unspecified, lymph nodes of head, face, and neck
ICD Code C83.91
Non-follicular (diffuse) lymphoma, unspecified, lymph nodes of head, face, and neck
ICD Code C85.91
Non-Hodgkin lymphoma, unspecified, lymph nodes of head, face, and neck
ICD Code C88.91
Malignant immunoproliferative disease, unspecified, in remission