Nodal involvement in gastric MALT lymphoma

In gastric extranodal marginal zone lymphoma, the frequency of nodal involvement and its pattern varies depending whether there is a large cell component to the lymphoma and on the depth of invasion¹

Frequency of nodal involvement:

	cases with involved nodes	proportion of nodes involved	depth of invasion cases with involved nodes proportion of nodes involved
pure MALToma	2/13	2/408 (0.5%)	mucosal 0/2 0/38 submucosal 2/10 2/354 muscle 0/0 0/0 serosal 0/1 0/16
MALToma with a minor (less than 20% of the entire tumour) large B-cell lymphoma	5/6	21/253 (8%)	mucosal 1/1 2/53 submucosal 2/3 5/127 muscle 1/1 6/37 serosal 1/1 8/36
large B-cell lymphoma with MALT lymphoma	9/12	149/429 (35%)	mucosal 0/0 0/0 submucosal 3/4 20/143 muscle 3/4 96/176 serosal 3/4 33/110
pure large B-cell lymphoma	6/6	27/223 (12%)	mucosal 0/0 0/0 submucosal 2/2 6/81 muscle 2/2 15/73 serosal 2/2 6/69
Overall	22/27	199/1313 (15%)

Pattern of nodal involvement:

	most common pattern	lymph nodes involved	sinusoidal	sinusoidal and subsinusoidal	sinusoidal	sinusoidal and follicular	follicular	sinusoidal and diffuse	subsinusoidal and diffuse	follicular and diffuse	diffuse
pure MALToma	mainly sinusoidal / subsinusoidal	2/409	0	1	0	0	0	0	0	0	1
MALToma with a minor (less than 20% of the entire tumour) large B-cell lymphoma	mainly sinusoidal / subsinusoidal	21/249	4	13	0	0	1	0	0	1	2
large B-cell lymphoma with MALT lymphoma	mainly diffuse	149/430	2	26	6	3	12	0	5	14	81
pure large B-cell lymphoma	mainly follicular or diffuse	27/225	1	2	2	1	6	2	2	4	7
Overall		199/1313	7	42	8	4	19	2	7	19	91

Despite the frequency of colonisation of follicles within the primary MALToma, a follicular pattern is uncommon in the nodal metastases.

Differential diagnoses:

• sinusoidal pattern: sinus histiocytosis. CD20 highlights the B-cells of sinusoidal involvement.

• follicular pattern: follicular hyperplasia. Neoplastic follicles lack a mantle, tingible body macrophages and CD21-positive follicular dendritic cells and are CD10 negative.

References

¹Ko, Y.H., Han, J.J., Noh, J.H. and Ree, H.J. Lymph nodes in gastric B-cell lymphoma: pattern of involvement and early histological changes. Histopathology 2002;40:497-504.