Count phyllodes mitoses in the hotspot, and the lymphocyte count flags delayed neurotoxicity after cilta-cel

The edition in brief

An international group of breast pathologists recommends counting stromal mitoses in phyllodes tumours at the hotspot, the most mitotically active area, with field diameter standardised for the microscope used, to make grading more reproducible. In myeloma patients given BCMA-directed CAR-T cells, a multicentre cohort of 532 found that a higher peak absolute lymphocyte count was associated with delayed neurotoxicity, particularly parkinsonism after ciltacabtagene autoleucel; a peak of at least 3 × 10³/µL, or 2.5 × 10³/µL after a twofold rise, had 81% sensitivity and 59% specificity. NF2/Merlin immunohistochemistry showed loss in 10 of 16 collecting duct carcinomas and none of 35 upper tract urothelial carcinomas, making loss a specific but incomplete marker in that differential. In 108 molecularly confirmed clear cell renal cell carcinomas, CK7 was positive in 30%, more often in primaries and lower-grade patterns, and CA9 was negative in 15% of metastases. Ten years of updates to the Sherloc variant classification framework reclassified 3,834 of 32,241 tracked variants of uncertain significance, 73% through evidence criteria added after the first version. The pearl: in an infiltrative renal tumour with tubules, put urothelial markers on the panel before calling collecting duct carcinoma.