Marrow hypercellularity found in 38% of evaluable essential thrombocythemia patients

A single-center observational study published in Leukemia examined marrow cellularity in essential thrombocythemia (ET), where normocellularity is often considered typical. Researchers at Weill Cornell Medicine used natural language processing to extract cellularity information from hematopathology reports and manually reviewed diagnoses against fifth-edition WHO/ICC criteria. Patients without marrow biopsies were excluded, and competing diagnoses, particularly prefibrotic myelofibrosis and polycythemia vera, were excluded using established WHO criteria.

Cellularity estimates were available in 338 pathology reports from 273 distinct patients among 497 patients with ET treated at the center. Age-adjusted hypercellularity was documented in 38% of reports and in 103 of 273 evaluable patients (38%). Estimates had been made by experienced hematopathologists across multiple decades of institutional practice.

These findings indicate that hypercellularity can occur in otherwise WHO-defined ET; normal marrow cellularity is not required by current WHO or ICC diagnostic criteria. Interpretation is limited by the single-center design and incomplete availability of cellularity estimates. Although the article title describes hypercellularity as clinically neutral, the supplied subscription preview does not include clinical outcome comparisons, follow-up duration, or effect estimates supporting that conclusion.