2026 ICD-10-CM Diagnosis Code R59.9Enlarged lymph nodes, unspecified

ICD-10-CM Codes›R00–R99›R50-R69›R59

ICD-10-CM R59.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R59.9 is a billable ICD-10-CM diagnosis code for enlarged lymph nodes, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other general signs and symptoms.

Code Identity

ICD-10-CM Code
R59.9
Billable Status
Yes — Valid for Submission
Code Describes
Enlarged lymph nodes, unspecified
Short Description
Enlarged lymph nodes, unspecified
Same as the full description in the CMS dataset.
Parent Code
R59
Enlarged lymph nodes

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR50-R69General symptoms and signs
CategoryR59Enlarged lymph nodes
This CodeR59.9Enlarged lymph nodes, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Castleman disease
  • Finding of lymph node
  • Firm lymph node
  • Fluctuant lymph node
  • Hyperplastic lymph node
  • Lymphoid hyperplasia
  • Pulmonary venous hypertension due to compression of pulmonary great vein
  • Pulmonary venous hypertension due to compression of pulmonary great vein by lymphadenopathy
  • Shotty lymph node

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Adenopathy(lymph gland)
    • Enlargement, enlarged
      • lymph gland or node
    • Hyperplasia, hyperplastic
      • lymph gland or node
    • Hypertrophy, hypertrophic
      • gland, glandular
    • Hypertrophy, hypertrophic
      • lymph, lymphatic gland
    • Swelling(of)
      • glands

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM016
Other general signs and symptoms
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Castleman Disease

    large benign, hyperplastic lymph nodes. the more common hyaline vascular subtype is characterized by small hyaline vascular follicles and interfollicular capillary proliferations. plasma cells are often present and represent another subtype with the plasma cells containing igm and immunoglobulin a.

  • Orbital Reactive Lymphoid Hyperplasia|Reactive Lymphoid Hyperplasia of the Orbit

    a non-neoplastic diffuse proliferation of lymphocytes in the orbital soft tissue associated with the presence of scattered irregular secondary lymphoid follicles. it usually presents as unilateral painless palpable mass.

  • Primary Choroid Non-Hodgkin Lymphoma|Choroidal Reactive Lymphoid Hyperplasia|Primary Choroidal Lymphoma|Primary Choroidal Non-Hodgkin Lymphoma

    an indolent, low-grade b-cell non-hodgkin lymphoma that arises from the choroid. it is characterized by the presence of a diffuse infiltrate of small, round lymphocytes. lymphoid follicles with germinal centers may be present. in the past these tumors were termed 'reactive lymphoid hyperplasia'. now they are considered low-grade b-cell lymphomas, most commonly extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue.

  • Atypical Gastric Lymphoid Hyperplasia|Atypical Gastric Lymphoid Hyperplasia of Stomach|Atypical Gastric Lymphoid Hyperplasia of the Stomach

    an atypical lymphoid hyperplasia involving the gastric mucosa.

  • Atypical Lymphoproliferative Disorder|Atypical Lymphoid Hyperplasia

    a lymphoproliferative disorder characterized by the presence of an atypical lymphocytic infiltrate.

  • Benign Lymphoid Hyperplasia

    a polyclonal proliferation of lymphocytes without evidence of cytologic atypia.

  • Castleman Disease, Hyaline-Vascular Type|Angiofollicular Lymphoid Hyperplasia, Hyaline-Vascular Type|Castleman's Disease, Hyaline-Vascular Type

    the commonest type of castleman disease. it is seen most commonly in the mediastinum. histologically this is characterized by hyalinized germinal centers surrounded by small lymphocytes in a concentric fashion, giving an onion skin appearance.

  • Castleman Disease, Plasma Cell Type|Angiofollicular Lymphoid Hyperplasia, Plasma Cell Type|Castleman's Disease, Plasma Cell Type

    castleman disease characterized by the presence of prominent hyalinized vessels in the germinal centers and prominent sheets of plasma cells in the interfollicular areas.

  • Castleman Disease|AFLH|Angiofollicular Lymphoid Hyperplasia|Castleman's Disease|Castleman's Tumor|Castleman's disease|GLNH|Giant Lymph Node Hyperplasia

    a disorder characterized by lymphoid hyperplasia in the lymph nodes. there are two histologic variants recognized: the hyaline-vascular type and the plasma cell type. in the hyaline vascular type there are hyalinized vessels present in the lymphoid follicles. in the plasma cell type there is pronounced plasma cell proliferation. clinically, the disease may be localized; manifested with localized lymphadenopathy, or multicentric; manifested with generalized lymphadenopathy, fever, organomegaly, and sometimes poems syndrome. in contrast to patients with localized disease who are usually cured following resection of the lesion, patients with the multicentric form of the disease may follow a progressive clinical course, complicated by infection, kaposi sarcoma or lymphoma.

  • Cervical Florid Reactive Lymphoid Hyperplasia

    a dense, superficial benign lymphoid cell proliferation in the cervix. it almost always occurs in premenopausal women. it is composed of a mixture of large and small lymphocytes including immunoblasts. plasma cells and neutrophils are also present. immunohistochemical studies reveal a mixture of b and t lymphocytes, and polytypic plasma cells.

  • Conjunctival Reactive Lymphoid Hyperplasia

    a polyclonal proliferation of lymphoid tissue in the conjunctiva that typically occurs in young adults. it usually presents as a unilateral, red or orange, painless swelling and is probably caused by chronic antigen stimulation. (who 2018)

  • Epithelioid Hemangioma|Angiolymphoid Hyperplasia with Eosinophilia|Epithelioid hemangioma|Histiocytoid Hemangioma|Histiocytoid hemangioma

    a hemangioma characterized by the presence of epithelioid endothelial cells.

  • Follicular Bronchitis/Bronchiolitis|Follicular Hyperplasia of BALT|Pulmonary Lymphoid Hyperplasia

    a non-neoplastic disorder characterized by the formation of reactive lymphoid follicles adjacent to distal bronchi and bronchioles. it presents with mild shortness of breath and is associated with immunodeficiency syndromes and collagen vascular disorders.

  • Immunodeficiency-Related Lymphoproliferative Disorder|Immunodeficiency-Associated Lymphoproliferative Disorder|Lymphoid Hyperplasia Arising in Setting of Immune Deficiency/Dysregulation

    a lymphoproliferative disorder that occurs in a patient with immunodeficiency.

  • Lacrimal Gland Reactive Lymphoid Hyperplasia

    a polyclonal proliferation of lymphoid tissue in the lacrimal gland. it usually presents as painless palpable masses leading to globe displacement, decreased motility, diplopia, and ptosis. it has a tendency to involve bilateral lacrimal glands. there is a higher incidence in females and in the setting of autoimmune disease. (who 2018)

  • Lymphoid Hyperplasia

    a benign or malignant, diffuse and/or follicular lymphocytic proliferation.

  • Multicentric Castleman Disease|Idiopathic Multicentric Castleman Disease|MCD|Multicentric Angiofollicular Lymphoid Hyperplasia|Multicentric Angiofollicular Lymphoid Hyperplasia|Multicentric Castleman's Disease|iMCD

    castleman disease characterized by fever, generalized lymphadenopathy, hypergammaglobulinemia, and dysfunction of multiple organs. other signs and symptoms include anemia, thrombocytopenia, hepatomegaly, peripheral neuropathy and pleural effusions. morphologically, in the majority of cases the lymph nodes show features of castleman disease of the plasma cell type. in a minority of cases, changes of castleman disease of the hyaline-vascular type are seen. in contrast to patients with localized disease who are usually cured following resection of the lesion, patients with the multicentric form of the disease may follow a progressive clinical course, complicated by infection, kaposi sarcoma, or lymphoma.

  • Nodular Lymphoid Hyperplasia of Lung

    a rare, reactive lesion in the lung parenchyma. it is characterized by the formation of a single or several nodules that are composed of lymphocytic infiltrates with reactive germinal centers.

  • Primary Choroidal Non-Hodgkin Lymphoma|Choroidal Reactive Lymphoid Hyperplasia|Primary Choroidal Lymphoma

    an indolent, low-grade b-cell non-hodgkin lymphoma that arises from the choroid. it is characterized by the presence of a diffuse infiltrate of small, round lymphocytes. lymphoid follicles with germinal centers may be present. in the past these tumors were termed 'reactive lymphoid hyperplasia'. now they are considered low-grade b-cell lymphomas, most commonly extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue.

  • Primary Uveal Non-Hodgkin Lymphoma|Primary Uveal Lymphoma|Uveal Reactive Lymphoid Hyperplasia

    an indolent, low-grade b-cell non-hodgkin lymphoma that arises from the choroid, iris, or ciliary body. it is characterized by the presence of a diffuse infiltrate of small, round lymphocytes. lymphoid follicles with germinal centers may be present. in the past these tumors were termed 'reactive lymphoid hyperplasia'. now they are considered low-grade b-cell lymphomas, most commonly extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue.

  • Skin Epithelioid Hemangioma|Angiolymphoid Cutaneous Hyperplasia|Angiolymphoid Hyperplasia of Skin|Angiolymphoid Hyperplasia of the Skin|Epithelioid Hemangioma of Skin|Epithelioid Hemangioma of the Skin|Histiocytoid Hemangioma of Skin|Histiocytoid Hemangioma of the Skin

    a hemangioma arising from the skin. it is characterized by the presence of epithelioid endothelial cells.

  • Unicentric Castleman Disease|Localized Angiofollicular Lymphoid Hyperplasia|Localized Angiofollicular Lymphoid Hyperplasia|Localized Castleman Disease|UCD

    castleman disease that presents with localized lymphadenopathy.

  • Reactive Lymphoid Hyperplasia|Benign Lymphoid Hyperplasia

    a non-neoplastic proliferation of lymphocytes in lymph nodes and/or extranodal sites.

  • Skin Epithelioid Hemangioma|Angiolymphoid Cutaneous Hyperplasia|Angiolymphoid Hyperplasia of Skin|Angiolymphoid Hyperplasia of the Skin|Epithelioid Hemangioma of Skin|Epithelioid Hemangioma of the Skin|Histiocytoid Hemangioma of Skin|Histiocytoid Hemangioma of the Skin

    a hemangioma that arises from the skin and is characterized by the presence of epithelioid endothelial cells.

Convert R59.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
785.6 Enlargement lymph nodes
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R59.9Overview

Is R59.9 (Enlarged lymph nodes) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report enlarged lymph nodes, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does R59.9 group to?

When enlarged lymph nodes, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

Can R59.9 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the enlarged lymph nodes, unspecified is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R59.9?

Under the General Equivalence Mappings, enlarged lymph nodes, unspecified converts to ICD-9-CM 785.6 (enlargement lymph nodes). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.