ICD-10 Code C85.13 – Unspecified B-cell lymphoma, intra-abdominal lymph nodes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C85.13 – Unspecified B-cell lymphoma, intra-abdominal lymph nodes
What it is
C85.13 identifies a B-cell lymphoma involving the intra-abdominal lymph nodes when the specific subtype is not documented. Use it for malignant lymphoid disease in abdominal nodal sites with no more precise classification.
Clinical signs
Clinical features vary; refer to documentation. Patients may have enlarged intra-abdominal lymph nodes found on imaging, biopsy, or during evaluation for abdominal pain, fullness, or unexplained systemic symptoms.
When to use this code
Use this code when the record states unspecified B-cell lymphoma and specifies intra-abdominal lymph nodes as the site. It is appropriate when pathology confirms B-cell lymphoma but the exact histologic subtype is not named. Check documentation if the disease is described as primary, secondary, or more specifically classified.
Do not use for
Do not use it if the lymphoma type is documented more specifically, such as a defined B-cell lymphoma subtype. Also avoid it when the involved site is not intra-abdominal lymph nodes or when the diagnosis is uncertain.
Coding tip
Code the most specific lymphoma subtype and nodal location documented; if either is missing, confirm the report before assigning C85.13.