Secondary Lymphoid Tissues ›› Mucosa-Associated Lymphoid Tissue or MALT ›› MALT ›› Normal
GI Tract (Non-Gastric, e.g. Small Bowel): Mucosa Associated Lymphoid Tissue (MALT)

›Microscopic Features:
- Normal Lymphoid tissue that is associated with certain mucosa such as the small intestinal Peyer's patches
- As opposed to normal lymph nodes, these Mucosa Associated Lymphoid Tissue or MALT are not encapsulated
- Similar to lymph nodes, they are comprised of follicles (primary and secondary) and interfollicular areas
- The primary follicles (not antigen stimulated and lacks a germinal center) and secondary follicles (antigen stimulated with a germinal center in the middle) are the B-cell zones
- The interfollicular (between follicles) areas are the T-cell zones
›Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
- PB: N/A
- BM: N/A
- LN: N/A
›May Resemble:
- Mantle Cell Lymphoma
- Normal reactive Lymph node
- Normal Mucosa Associated Lymphoid Tissue (MALT)
- Normal Spleen
›Differential Diagnoses:
Follicular lymphoma
Mantle Cell Lymphoma
Reactive lymphoid hyperplasia
Mantle Cell Lymphoma
Reactive lymphoid hyperplasia
›Classic Immunophenotype:
- "T"-cells have the "Tiny" CDs: CD2, CD3, CD4, CD5, CD7, CD8
- "B"-cells have the "Bigger" CDs: CD19, CD20, CD22
›Misc:
Similar to lymph nodes and the spleen, the primary follicles (not antigen stimulated and lacks a germinal center) and secondary follicles (antigen stimulated with a germinal center in the middle) are the B-cell zones and the the interfollicular (between follicles) areas are the T-cell zones