The edition · Pathology
p53 immunohistochemistry in Barrett's biopsies held up in a nationwide expert panel
A Dutch review of 1146 consultation cases found substantial agreement on p53 patterns and frequent diagnostic reclassification. Also: functional scoring splits monoallelic TP53 MDS into high- and low-risk groups, and how far pan-TRK staining can stand in for molecular testing in Reed naevus.
The edition in brief
The Dutch Esophageal Pathology Panel reviewed 1146 consecutive Barrett's oesophagus consultation cases. Agreement on p53 immunohistochemistry patterns between referring hospitals and the panel was κ 0.61, and among 13 panel pathologists κ 0.65; 24% of referring p53 assessments were reclassified. Aberrant p53 moved some non-dysplastic biopsies to indefinite or low-grade dysplasia, and resolved over half of indefinite cases, mostly towards low-grade dysplasia. In 4505 patients with myelodysplastic neoplasms from two cohorts, a functional phenotype score for TP53 variants split monoallelic cases sharply: high-score variants with VAF of at least 22% behaved like multi-hit TP53 (median leukaemia-free survival 9.2 months), while low-score, low-VAF cases behaved like wild type (44.7 months). In 79 pigmented spindle cell naevi of Reed, an optimised pan-TRK stain was highly specific for NTRK3 rearrangement but detected only about a third of cases, so a negative stain does not exclude a fusion. The pearl covers the null-pattern p53 stain.
Not all single-hit TP53 mutations in MDS are equal: a functional score separated outcomes
Report TP53 variant identity and VAF precisely in MDS, since both appear to change prognosis within the monoallelic group.
Pan-TRK staining in Reed naevus: specific but misses two thirds of NTRK3 fusions
Pan-TRK immunohistochemistry can confirm but not exclude NTRK3 fusion in Reed naevus; use molecular testing when a negative result would change the diagnosis.
A completely negative p53 stain is not a reassuring result
Read complete absence of p53 staining in lesional cells, with a positive internal control, as an aberrant null pattern, not as normal.
p53 immunohistochemistry in Barrett's oesophagus was reproducible and changed diagnoses
Consider p53 immunohistochemistry with standardised pattern criteria for Barrett's biopsies that are indefinite or possibly dysplastic, read alongside H&E.
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