The edition · Pathology
Functional scoring splits monoallelic TP53 myelodysplasia into very different prognoses
In 4,505 patients with myelodysplastic neoplasms, the functional effect and allele fraction of a single TP53 mutation separated outcomes similar to wild-type from those similar to multi-hit disease. Also: lymph node morphology in colorectal cancer, Merkel cell carcinoma in younger patients, and the limits of pan-TRK staining.
The edition in brief
Two cohorts totalling 4,505 patients with myelodysplastic neoplasms showed median leukaemia-free survival of 37.2 months with wild-type TP53, 19.2 months with a single mutation and 7.8 months with multi-hit disease. Within single-mutation cases, a high functional phenotype score gave 12.6 months against 43.3 months for a low score. High score with a variant allele fraction of 22% or more resembled multi-hit disease. A multicentre study of 754 colorectal cancer patients classified non-metastatic lymph nodes into three H&E subtypes with high interobserver agreement and a prognostic model with external C-index of about 0.75. A single-centre series of 13 younger patients with Merkel cell carcinoma showed frequent immune suppression and metastases. In 79 pigmented spindle cell naevi of Reed, optimised pan-TRK staining had specificity and positive predictive value of 92% to 96% but sensitivity of 36% against molecular assays.
Functional annotation separates good and poor prognosis in monoallelic TP53 myelodysplasia
Consider reporting variant allele fraction and, where validated, variant function alongside allelic state for TP53-mutated MDS.
Non-metastatic lymph nodes in colorectal cancer fall into three reproducible H&E subtypes
Note immune-stromal features of negative nodes as a research direction, without changing signed-out staging.
Merkel cell carcinoma under 50: a small series with frequent immune suppression and spread
Consider Merkel cell carcinoma in younger patients with suspicious neuroendocrine cutaneous tumours, especially if immunosuppressed.
A negative screening stain does not rule out the alteration it screens for
Treat a negative surrogate stain as non-informative when the clinical suspicion is high.
Optimised pan-TRK staining in Reed naevus: reliable when positive, insensitive when negative
Consider using optimised pan-TRK staining to support, not exclude, an NTRK3 fusion in Reed naevus.
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