Case Example 15 (Multiple Primaries and Histology)

Patient noted to have a large retroperitoneal mass. Pelvic biopsy positive for Diffuse large B-cell lymphoma (9680/3). No other disease present.

Following month a bone marrow biopsy is done which showed low grade B-cell lymphoma consistent with follicular lymphoma. Negative for large B-cell lymphoma.

Coding of the case (Lymphoma schema)

Data Item-Primary #1	Coding
M Rule	M2: Single histology, single primary
PH Rule	PH18: 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. Bullet b says to code C772 for a retroperitoneal mass
Primary site	C772: Intrabdominal lymph nodes
Histology	9680/3: Diffuse large B-cell lymphoma
Diagnostic confirmation	1 (positive histology)
EOD Primary Tumor	100 (single lymph node regional involved)
EOD Regional Nodes	888 (not applicable)
EOD Mets	88 (not applicable)
Summary Stage	1 (single lymph node regional involved)
Mets at Dx Data Items (all 6)	Mets at Dx-Distant lymph nodes: 8, remaining mets at dx fields: 0

Data Item-Primary #2	Coding
M Rule	M11: Chronic and acute neoplasms diagnosed during initial workup with two biopsies 1st biopsy is the DLBCL, 2nd biopsy is the Follicular lymphoma
PH Rule	PH26: Code to bone marrow This rule specifically states that the only thing that can be involved is the bone marrow; however, in this situation, the lymph node involvement is recorded in another primary.
Primary site	C421: Bone marrow
Histology	9690/3: Follicular lymphoma, NOS (no grade specified)
Diagnostic confirmation	1 (positive histology)
EOD Primary Tumor	800 (bone marrow involvement)
EOD Regional Nodes	888 (not applicable)
EOD Mets	88 (not applicable)
Summary Stage	7 (bone marrow involvement)
Mets at Dx Data Items (all 6)	8 (not applicable)

Updated: December 2, 2025