Evaluation of lymph node ratio and morphologic patterns of nodal reactive hyperplasia in primary organ malignancy.

Background: Lymph node ratio (LNR) in cancer staging is the ratio of nodal metastases (LNM) to total nodes harvested (LNH). Reactive nodal hyperplasia can exhibit morphological patterns I to VI.

Aims: To measure LNR and evaluate it with tumor stage, tumor grade, LN reactive patterns, and LN size.

Setting and Design: Retrospective, observational study of 100 cancer resections including breast, gastrointestinal (GIT), genitourinary (GUT), and head, face, neck, and thyroid (HFNT).

Materials and Methods: Total 1463 LNs were reviewed for metastases and reactivity patterns I-VI as per the World Health Organization (WHO) protocol. LNR was calculated from LNM and LNH.

Statistical Analysis Used: Association between qualitative variables was assessed by the Chi-square test and Fisher's exact test, those between quantitative variables using the unpaired t-test and Mann-Whitney U test.

Results: Mean LNH (23.7) was highest in HFNT and lowest (6.6) in GIT (P = 0.008). Mean LNR was highest (0.29) in breast and least (0.06) in HFNT (P = 0.861). Commonest LN reactive patterns were sinus histiocytosis (60), mixed (48), and follicular hyperplasia (46) (P = 0.000). Maximum cases of breast (59.6%), GUT (53.8%), and HFNT (45%) belonged to stage T2, while GIT (60.0%) to stage T3 (P = 0.000). Maximum well-differentiated cases belonged to HFNT (13, 59.0%), while moderately poorly differentiated cases of breast (38, 55.8% and 7, 70.0%) (P = 0.000). The largest and smallest metastatic LN was 2.4 cm and 0.4 cm (P = 0.009). LNs with thickened capsule showed nodal metastases in 75.7% (P = 0.003871).

Conclusions: LNH and LNR cut-off values show organ-wise variation and need standardization. LNR shows stronger relation with tumor grade than tumor stage. Commonest LN reactive patterns include sinus histiocytosis and follicular hyperplasia. Thickened LN capsule strongly suggests nodal metastases. A longitudinal follow-up is warranted to study prognostic association between LNR and LN reactive pattern.