What does a minimal increase in lymphocytes in relation to polyps indicate?

Minimal Increase in Lymphocytes in Relation to Polyps

A minimal increase in lymphocytes in polyp tissue is a normal finding that does not indicate malignancy or require additional intervention, but when found as the sole pathologic finding in a specimen clinically diagnosed as a polyp, it warrants deeper level sectioning to exclude an underlying neoplastic lesion.

Clinical Significance by Polyp Location

Nasal Polyps

• Lymphocyte infiltration in nasal polyps is a consistent, expected finding that reflects chronic inflammatory processes rather than malignancy 1, 2
• The frequency of lymphocytes and lymphocyte subsets (including CD2+, CD3+, CD4+, CD8+ cells) shows no significant difference between nasal polyps and normal nasal mucosa 2
• Nasal polyps typically contain more CD8+ (suppressor/cytotoxic) cells than CD4+ (helper/inducer) cells, with T cell lineage predominating over B cell lineage 1
• A lone increase in lymphocytes without other inflammatory cells is uncommon in typical nasal polyps (occurring in <10% of cases), and when present should prompt consideration of alternative diagnoses such as lymphocytic interstitial pneumonia or lymphoma 3

Colorectal Polyps

• When lymphoid aggregates are the only finding on initial sections of a specimen submitted clinically as a polyp, deeper level sectioning is mandatory 4
• In specimens initially showing only lymphoid aggregates or no pathologic diagnosis, additional diagnostic findings (including neoplastic lesions) are identified in 22.8% of cases when deeper levels are examined 4
• Neoplastic findings are discovered in 9.6% of cases that initially showed only lymphoid aggregates, with tubular adenomas sometimes found as deep as levels 7 and 8 4
• The neutrophil-to-lymphocyte ratio may help distinguish neoplastic from non-neoplastic polyps, with neoplastic polyps showing a mean NLR of 3.32±2.54 versus 2.98±3.16 for non-neoplastic polyps, though sensitivity and specificity are limited 5

Pathologic Interpretation Pitfalls

• Lymphoid aggregates can obscure underlying adenomatous tissue in colorectal specimens, making level sectioning through the entire block essential 4
• The presence of lymphocytes alone does not exclude pseudoinvasion or true malignant invasion in polyp specimens 3
• Retraction artifact around tumor nests can simulate lymphatic invasion, and true lymphatic invasion requires confirmation with endothelial markers (D2-40, CD31, CD34, or factor VIII) 3

Recommended Diagnostic Approach

For Nasal Polyps:

• Document the presence and relative proportions of lymphocytes, eosinophils, neutrophils, and plasma cells 1, 2
• If lymphocytes are markedly increased without other inflammatory cells, consider bronchoalveolar lavage to exclude systemic conditions such as sarcoidosis, hypersensitivity pneumonitis, or lymphoproliferative disorders 3

For Colorectal Polyps:

• Perform at least 5 additional level sections through each block when initial sections show only lymphoid aggregates or no diagnostic findings 4
• Most diagnostic findings appear in levels 4 or 5, but continue to levels 7-8 to exclude tubular adenomas 4
• Evaluate for margin status, tumor differentiation, and lymphatic/vascular invasion if any neoplastic tissue is identified 3

When to Escalate Evaluation

• Persistent lymphocytosis in nasal polyps warrants flow cytometry to characterize lymphocyte subsets and exclude lymphoproliferative disorders 1, 2
• In colorectal specimens, if deeper levels reveal adenomatous tissue with lymphocytic infiltration, assess for unfavorable histologic features (positive margins, poor differentiation, lymphovascular invasion) that would necessitate surgical resection 3
• Consider immunohistochemical staining with D2-40 to definitively identify lymphatic channels if lymphatic invasion is suspected 3, 6