06-12-2026 Primary Site Starts with the Manual-Not the Drop Down
Scenario:
- Scans show 6cm Mesenteric Mass (only site of activity)
- Bx mesenteric mass: large b cell lymphoma, germinal center type
Question: What is primary site?
- C77.2 Intra-abdominal lymph nodes
- C48.1 Mesentery
- C77.9 Lymph node, NOS
Answer: C77.2 Intra-abdominal lymph nodes
Hematopoietic and Lymphoid Neoplasm Coding Manual
Rule PH18: Nodal Lymphomas described as a “mass”
- Applicable for Hodgkin & non-Hodgkin lymphomas only: Code the primary site to the specified lymph node region when the site of the lymphoma is described ONLY as a mass and there is no additional lymph node involvement.
- Mediastinal lymph nodes (C771) when the site of the lymphoma is described only as a mediastinal mass.
Example: Lymphoplasmacytic lymphoma with an anterior mediastinal mass. No other involvement. Rule PH18 applies. Primary site C771.
- Intra-abdominal lymph nodes (C772) when the site of the lymphoma is described only as a retroperitoneal mass or mesenteric mass.
- Inguinal lymph nodes (C774) when the site of the lymphoma is described only as an inguinal mass.
- Pelvic lymph nodes (C775) when the site of the lymphoma is described only as a pelvic mass.
- Do not apply this rule to any other descriptions of “mass.”
- Example: LT Paravertebral Mass. Imaging describes the location of a soft tissue lesion to the LT of T11-T12. Paravertebral mass is not covered in Rule PH18, so this cannot be used for this case scenario. (Note: This is a mass surrounding the vertebra, assign primary site to vertebrae).
- Do not apply this rule when multiple lymph nodes are involved. See PH21.
Example: 2023 patient has CT scan showing a bulky mediastinal mass, PET shows mediastinal mass and hypermetabolic nodal tissue throughout the cervical, supraclavicular, subpectoral and axillary nodal stations. Mediastinal mass bx showed classic Hodgkin lymphoma nodular sclerosis subtype 9663/3, and bone marrow bx was negative. Rule PH18 does not apply since multiple lymph node areas are involved
