The edition · Pathology
In small-bowel NETs, only the Ki67 of the mesenteric deposit predicted progression — stain the deposit, not only the primary
A Histopathology cohort on where to grade jejunoileal NETs, evidence that MTAP loss does not stand in for CDKN2A deletion in peritoneal mesothelioma, a methylation triage meta-analysis for HPV-positive women, and a copy-number split within TP53-mutated multiple-classifier endometrial cancer.
The edition in brief
Today's pathology edition closes on a Histopathology cohort (15 September) of 75 node-positive or deposit-bearing jejunoileal neuroendocrine tumours: in 68% the node or deposit Ki67 exceeded the primary's, and only the Ki67 of the largest mesenteric deposit predicted progression on multivariable analysis (HR 1.22 per 1% rise, 1.02 to 1.46). The lead is a Histopathology study (21 September) showing that in peritoneal mesothelioma, MTAP immunohistochemistry agreed with MTAP FISH but poorly with CDKN2A deletion (kappa 0.21), unlike pleural disease — so MTAP loss cannot be read as a CDKN2A surrogate in the peritoneum, though it may still support malignancy. A meta-analysis of 8 studies and 7494 women (Medicine, 18 September) reported PAX1/JAM3 methylation sensitivity 0.81 and specificity 0.95 for CIN2+, promising for HPV-positive triage but drawn largely from single-population studies. A Modern Pathology cohort (17 September) of 33 TP53-mutated multiple-classifier endometrial carcinomas found a copy-number-high third that carried all six recurrences, a hypothesis for now. The pearl is on naming the block you stained for Ki67.
Peritoneal mesothelioma: MTAP loss is not a stand-in for CDKN2A deletion
In peritoneal mesothelioma, report MTAP and CDKN2A status separately — MTAP IHC does not predict CDKN2A deletion there as it does in the pleura.
PAX1/JAM3 methylation for triaging HPV-positive women: sensitivity 0.81, specificity 0.95 for CIN2+
PAX1/JAM3 methylation looks accurate for triaging HPV-positive women, but keep cytology triage until it is validated against it head to head.
TP53-mutated multiple-classifier endometrial carcinoma: a copy-number-high third carried every recurrence
Keep classifying multiple-classifier endometrial carcinomas by the current algorithm, but flag high-grade or non-endometrioid ones to the tumour board.
Name the block you stained for Ki67
In every Ki67 report, state which lesion and block were stained and how the index was counted.
Small-bowel NETs: grade from the largest mesenteric deposit
For jejunoileal NETs with mesenteric deposits, stain the largest deposit for Ki67 and report it with the primary.
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