Nodular lymphoid hyperplasia versus malt lymphoma
| Histology and immunohistochemistry | Nodular lymphoid hyperplasia | MALT lymphoma |
| Architecture | Well circumscribed lesion, usually localised | May be localised but is infiltrative, often invading the pleura and bronchial cartilage |
| Lymphangitic spread | Focal, mild | Prominent |
| Cellularity | Reactive germinal centres with interfollicular small lymphocytes and plasma cells | Polymorphic: monocytoid B cells, centrocyte-like (cleaved) atypical lymphocytes and plasma cells |
| Germinal centres | Reactive with no follicular colonisation by neoplastic cells | Reactive with colonisation by neoplastic cells |
| Lymphoid population | Polymorphous | Monomorphous or polymorphous |
| Monocytoid B cells | Inconspicuous or absent | May be conspicuous |
| Plasma cells | Usually not extensive | May be extensive |
| Intranuclear inclusions (Dutcher bodies) | Absent | Variably present |
| Amyloid | Absent | May be abundant |
| Lymphoepithelial lesions | Absent | Variably present |
| Plaque-like pleural infiltration | Absent or inconspicuous | Variably present |
| Kappa/lambda reactivity | Polyclonal | Monoclonal in approximately 40% of cases |
| Bcl-2 reactivity | Negative germinal centres | Negative in the follicular centre cells but positive in the colonising neoplastic lymphocytes |
| Immunoglobulin heavy chain gene rearrangement | Negative | Positive in 60% |
Modified from references 1, 2, and 70.