C85.15 Unspecified B-cell lymphoma, lymph nodes of inguinal region and lower limb

ICD-10-CM Diagnosis Code C85.15: Unspecified B-cell lymphoma, lymph nodes of inguinal region and lower limb

ICD-10-CM code C85.15 designates an unspecified B-cell lymphoma located in the lymph nodes of the inguinal region and lower limb. This diagnostic concept is classified as a neoplastic process and is considered a billable diagnosis code. It maps to risk adjustment models for lymphoma and appears in payer billing guidance for B-cell lymphoma treatments. 1 6 4

Plain-language overview

Code C85.15 identifies an unspecified B-cell lymphoma involving the lymph nodes of the inguinal region and lower limb, meaning the anatomical location is confirmed but the specific lymphoma subtype is not classified. 6

What this code represents

The terminology record for C85.15 lists the preferred name as Unspecified B-cell lymphoma, lymph nodes of inguinal region and lower limb, and assigns it a semantic type of Neoplastic Process. 1

Within the ICD-10-CM hierarchy, C85.15 has a parent concept of C85.1, which is Unspecified B-cell lymphoma, and it falls under the chapter covering neoplasms and the section for malignant neoplasms of lymphoid, hematopoietic and related tissue. 1 6

Coding details

The diagnosis code C85.15 is considered billable, and under the CMS-HCC V28 risk adjustment model it maps to Lymphoma and Other Cancers with a community non-dual aged base RAF weight of 0.671. 6

Documentation considerations

To support the use of this code, clinical or imaging documentation must confirm the involvement of the lymph nodes of the inguinal region and lower limb. 6

Coverage and utilization context

Billing and coding guidelines for allogeneic hematopoietic cell transplantation for primary refractory or relapsed Hodgkin's and non-Hodgkin's lymphoma with B-cell or T-cell origin reference lymph nodes of the inguinal region. 4 5

What the sources add

While the CMS billing articles provide payer guidelines for B-cell lymphoma treatments, the terminology record establishes the official code definition and active status without detailing clinical manifestations or treatment protocols. 1 4

A research mapping resource groups multiple lymphoma diagnoses, including Unspecified B-cell lymphoma of the inguinal region and lower limb, under a single phecode for analytical purposes. 3

Clinical context

A separate clinical case report describes high-grade B-cell lymphoma presenting with peripheral nerve injury and notes that PET-CT imaging revealed multiple enlarged lymph nodes in the bilateral inguinal regions. 2

Sources

1. ICD-10-CM C85.15 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. High-grade B-cell lymphoma manifested as peripheral nerve injury: A case report — pmc.ncbi.nlm.nih.gov; accessed 2026-07-27.
3. Phecode 202.2 · ExPRSweb — csg.sph.umich.edu; accessed 2026-07-27.
4. Article - Billing and Coding: Allogeneic Hematopoietic Cell Transplantation for Primary Refractory or Relapsed Hodgkin's and Non-Hodgkin's Lymphoma with B-cell or T-cell Origin (A59175) — cms.gov; accessed 2026-07-27.
5. Article - Billing and Coding: Allogeneic Hematopoietic Cell Transplantation for Primary Refractory or Relapsed Hodgkin's and Non-Hodgkin's Lymphoma with B-cell or T-cell Origin (A59259) — cms.gov; accessed 2026-07-27.
6. 2026 ICD-10-CM C85.15: Unspecified B-cell lymphoma | HCC 21 — hccbuddy.com; accessed 2026-07-27.