We investigated the changes in chromosomal abnormalities in myeloproliferative neoplasm (MPN) patients during long-term follow-up. In total, 28 MPN patients (22 with primary myelofibrosis and 6 with polycythemia vera) were included. Among them, 25 patients underwent serial bone marrow (BM) biopsies during disease progression, and 3 patients had cytogenetic abnormalities at initial diagnosis but lacked follow-up BM biopsies. JAK2, CALR, and MPL mutation analyses were performed. Targeted sequencing analysis was conducted in 11 patients. Among the 28 patients, 21 (75.0%) had cytogenetic abnormalities either at diagnosis (8/26) or during follow-up. The median time from the initial analysis to the appearance of additional cytogenetic abnormalities was 8.4 years. Among the chromosomal abnormalities at initial diagnosis, trisomy 8 (3/26, 11.5%) was the most frequent, followed by gain of 1q, del(20q), and del(9q) (each in 2/26). Among all chromosomal abnormalities, including those that occurred during follow-up, the most frequent was del(20q) and +1q (8/28, 28.6%), followed by del(6p) (14.3%) and trisomy 8 (10.7%). Del(20q) was more frequent in CALR-mutated patients (4/6, 66.7%) than in JAK2-mutated patients (3/19, 15.8%, P = 0.016). The presence of cytogenetic abnormalities at initial diagnosis was associated with poor prognosis. Cytogenetic evolution may provide interesting insights into the disease course.
