Beyond the Bone Marrow: A Case Report of Extramedullary Hematopoiesis in Advanced Primary Myelofibrosis.

Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, cytopenias, splenomegaly, and extramedullary hematopoiesis (EMH). Although EMH most commonly involves the spleen and liver, extensive organ infiltration leading to portal hypertension and obstructive cholestasis is uncommon. We present the case of a 54-year-old man diagnosed with PMF who developed massive hepatosplenic EMH following prolonged interruptions to treatment caused by barriers to healthcare access. The disease progressed to an accelerated phase with extensive bone marrow fibrosis, grade 3 osteosclerosis, and 10.5% aberrant myeloid blasts without fulfilling diagnostic criteria for acute myeloid leukemia. Imaging demonstrated diffuse periportal infiltrative soft tissue causing biliary obstruction, massive splenomegaly, portal hypertension, and esophagogastric varices. The patient received hydroxyurea, ruxolitinib, and palliative hepatosplenic radiotherapy, achieving transient clinical and biochemical improvement. However, he subsequently developed radiation-induced bone marrow aplasia and died from progressive disease. This case underscores the aggressive clinical course of advanced PMF when continuous disease-modifying therapy is interrupted and highlights the importance of timely access to targeted treatment and a multidisciplinary approach for managing extensive EMH and its life-threatening complications.