2027 ICD-10-CM Diagnosis Code C77.4Secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes
ICD-10-CM Codes›C00–D49›C76-C80›C77
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 18
- Chronic Condition
C77.4 is a billable ICD-10-CM diagnosis code for secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 820 through 825, 840 through 842. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 24 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Secondary malignancies.
For Medicare Advantage risk adjustment, C77.4 maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid) under the V28 model, adding a risk factor of about 2.341 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C77.4 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Metastasis to lymph node from adenocarcinoma
- Metastatic adenocarcinoma to lymph node of lower limb
- Metastatic carcinoma to lymph node of lower limb
- Metastatic malignant neoplasm to femoral lymph nodes
- Metastatic malignant neoplasm to inguinal lymph nodes
- Metastatic malignant neoplasm to inguinal region
- Metastatic malignant neoplasm to lymph nodes of lower limb
- Metastatic malignant neoplasm to popliteal lymph nodes
- Metastatic malignant neoplasm to superficial inguinal lymph nodes
- Metastatic malignant neoplasm to thigh
- Metastatic malignant neoplasm to tibial lymph nodes
- Metastatic squamous cell carcinoma to lymph node
- Metastatic squamous cell carcinoma to lymph node of lower limb
- Neoplasm of femoral lymph nodes
- Neoplasm of popliteal lymph nodes
- Neoplasm of superficial inguinal lymph nodes
- Neoplasm of tibial lymph nodes
- Non-Hodgkin lymphoma of central nervous system metastatic to lymph node of lower limb
- Non-Hodgkin's lymphoma of central nervous system
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C77.4: its own notes plus those printed at C77 and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name C77.4, its category, or a range that includes it.
Applicable To 2
These notes mention C77.4.
Excludes2 1
These codes carry an Excludes2 note naming C77.4: its condition is not part of those codes, and both may be reported when the patient has both.
- Block C81-C96 Malignant neoplasms of lymphoid, hematopoietic and related tissuesecondary and unspecified neoplasm of lymph nodes (C77.-) names C77.-, which includes this code
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| lymph, lymphatic channel NEC › gland (secondary) › Cloquet | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › femoral | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › groin | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › inguina, inguinal | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › leg | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › limb › lower | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › lower limb | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › popliteal | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › Rosenmuller's | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › subinguinal | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
| lymph, lymphatic channel NEC › gland (secondary) › tibial | – | C77.4 | – | D36.0 | D48.7 | D49.89 |
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Convert C77.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C77.4Overview
Is C77.4 (Secondary and unspecified malignant neoplasm of lymph nodes) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C77.4 group to?
When secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes is the principal diagnosis on an inpatient stay, it groups to MS-DRG 841, 821, 822, 825, 842, 824, 840, 820, 823, with relative weights from 0.9948 to 6.2454 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C77.4 a CC or MCC?
CMS lists C77.4 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 24 closely related codes in its exclusion list.
Can C77.4 be reported with C88?
Not as a rule. The Excludes1 note at C77, which applies to C77.4, lists "malignant neoplasm of lymph nodes, specified as primary (C81-C86, C88, C96.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of C77.4?
Under the General Equivalence Mappings, secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes converts to ICD-9-CM 196.5 (mal neo lymph-inguin/leg). The mapping is a direct match.
What HCC is C77.4?
C77.4 (secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes) maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid), commonly written as HCC 18, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 8 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 20.
Does C77.4 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C77.4 adds a risk adjustment factor of about 2.341 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 1.110 to 2.537 depending on the payment segment). A more severe related category (HCC 17) supersedes it when both are reported. See the full factor table on the HCC 18 category page.
