Understanding the Similarities and Differences between Hepatic and Pulmonary Veno-Occlusive Disease

Hepatic veno-occlusive disease (HVOD), alias sinusoidal obstruction syndrome, may develop as a complication of chemotherapy in the setting of hematopoietic stem cell transplantation. HVOD is less frequently described after exposure to chemotherapy in the nontransplant setting and can also be a complication after ingestion of toxins, such as pyrrolizidine alkaloids. Veno-occlusive disease may also affect the lungs, and it is therefore termed pulmonary veno-occlusive disease (PVOD). Similarly, PVOD can develop after exposure to chemotherapeutic agents in the treatment of solid and hematological malignancies. In addition, PVOD has also been linked to autoimmune disorders and occupational solvent exposure. Finally, the heritable form of PVOD is due to biallelic mutations of the EIF2AK4 gene. Both HVOD and PVOD share common histopathological features and pathophysiologic mechanisms. Both clinical disorders are rare complications that can appear after exposure to the common inciting trigger of chemotherapeutic agents. The present review aims to summarize the current knowledge of HVOD and PVOD and to describe both similarities as well as differences regarding both conditions.