Secondary Lymphoid Tissues ›› Mucosa-Associated Lymphoid Tissue or 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

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