What histological change would be common in primary myelofibrosis (PMF)?

In primary myelofibrosis (PMF), one of the hallmark histological changes observed is marrow fibrosis. This is characterized by an increase in collagen deposition within the bone marrow, resulting in a fibrotic environment that disrupts normal hematopoiesis. The fibrotic changes typically stem from the abnormal proliferation of fibroblasts, which are stimulated by factors released by neoplastic cells, leading to the replacement of the normal hematopoietic tissue with fibrous tissue.

This phenomenon is a defining feature of PMF and can be assessed through histological examination using special stains such as reticulin or trichrome stains, which highlight the fibrous components within the marrow. The presence of significant bone marrow fibrosis can also correlate with clinical manifestations, such as splenomegaly, due to extramedullary hematopoiesis occurring in response to the dysfunction of the bone marrow.

Other options such as marrow hypercellularity, excess apoptotic cells, and marked smudge cells are not characteristic features of primary myelofibrosis. In fact, PMF often presents with variable cell lineages, frequently leading to reduced cellularity in advanced disease stages, which can complicate the overall clinical picture. Therefore, the presence