A routine lymphocyte count may flag delayed neurotoxicity after cilta-cel

The edition in brief

Today's pathology edition ends on a laboratory signal clinicians can act on. In a multicentre cohort of 532 patients with relapsed or refractory myeloma treated with ide-cel or cilta-cel, a higher peak absolute lymphocyte count was associated with delayed neurotoxicity, particularly parkinsonism after cilta-cel; a peak of at least 3 × 10³/μL, or at least 2.5 × 10³/μL after a twofold rise, identified higher risk with 81% sensitivity and 59% specificity. A flow cytometry sub-study showed very high CAR T-cell expansion in those affected. An expert group of breast pathologists recommends counting stromal mitoses in phyllodes tumours in the most active hotspot, calibrated to the microscope's field diameter, to make grading more reproducible. A series of 3,696 endometrioid carcinomas found nine with malignant squamous differentiation, which clustered at the invasive front and in nodal deposits, lost hormone receptors, and was often missed or misread on preoperative sampling. A study of 108 molecularly confirmed clear cell renal cell carcinomas found CK7 positivity in 30%, more often in primary and lower-grade tumours, and CA9-negative tumours only among metastases — patterns that can mislead a diagnosis made on immunohistochemistry alone. The pearl covers why a curettage grade is a provisional one.