Light-chain mRNA in situ hybridisation separates the Hodgkin grey zone

Design

Single-cohort diagnostic assay evaluation

Population

53 lymph node biopsies spanning the NLPHL-classic Hodgkin lymphoma spectrum

Primary outcome

Kappa/lambda mRNA expression pattern by entity

Effect

Canonical pattern in 13/13 typical NLPHL and 12/15 overlapping cases; classic Hodgkin negative or non-canonical

Telling nodular lymphocyte-predominant Hodgkin lymphoma from lymphocyte-rich classic Hodgkin lymphoma is one of the harder calls in haematopathology, and the overlapping cases sit in a biological grey zone. This study applied a dual kappa/lambda mRNA in situ hybridisation assay to 53 lymph node biopsies across the spectrum.

The canonical pattern — diffuse, strong cytoplasmic light-chain signal in the tumour cells — appeared in all typical nodular lymphocyte-predominant cases (13 of 13) and most overlapping cases (12 of 15, 80%). Classic Hodgkin lymphoma was either negative or showed only faint, non-canonical signals, seen in about half of lymphocyte-rich cases. A minority of overlapping cases showed non-canonical staining, including two Epstein-Barr-virus-positive tumours.

For a reporting pathologist, this is a potential ancillary test to resolve morphologically and immunophenotypically ambiguous cases, reclassifying many overlapping tumours as nodular lymphocyte-predominant with aberrant features. It is a single-cohort study of a novel assay, so it needs validation and access before it enters routine use.

• Dual kappa/lambda mRNA in situ hybridisation applied to 53 lymph node biopsies across the Hodgkin spectrum.
• Canonical diffuse strong light-chain signal in all typical NLPHL (13 of 13) and 80% of overlapping cases.
• Classic Hodgkin lymphoma was negative or showed only non-canonical, faint signals.
• The assay reclassified most overlapping cases as NLPHL with aberrant features.
• A single-cohort study of a novel assay; validate before routine use.

Why it matters

It offers an objective ancillary signal for a differential that currently rests on a difficult combination of morphology and immunophenotype.

Don't overread it

This was a single-cohort evaluation of a novel assay; the clean separation needs confirmation in independent, larger series.

The statistics, in plain English

The canonical pattern was present in all typical cases and absent from classic Hodgkin lymphoma, so the separation is clean in this cohort; small numbers in each subgroup mean the exact proportions will shift with wider testing.

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