hematogeen

Hematogeen, or hematogenous in English, refers to processes that originate in or spread through the bloodstream. In medical usage, it describes how pathogens or tumor cells disseminate from a primary site into the circulatory system and seed distant tissues.

Etymology and usage:

The term derives from Greek roots meaning blood-producing or blood-based. Hematogenous spread is a common description in oncology and infectious disease, indicating systemic dissemination via the bloodstream rather than through adjacent tissues or the lymphatic system.

Mechanisms:

Hematogenous spread typically begins with intravasation, where malignant cells or pathogens cross blood vessel walls. Once in the circulation, cells or organisms must evade immune defenses, survive hemodynamic forces, and later extravasate at distant sites to establish secondary foci. Successful colonization depends on interactions between circulating cells and the endothelium, as well as the microenvironment of target organs.

Clinical patterns and examples:

In cancer, hematogenous metastasis is a major route for distant spread; common targets include the liver, lungs, bones, and brain, with patterns influenced by anatomical blood flow. In infections, hematogenous dissemination can lead to bacteremia, fungemia, or viremia, potentially progressing to sepsis if uncontrolled.

Diagnosis and management:

Diagnosis relies on imaging to identify metastatic lesions, tissue biopsy for confirmation, and laboratory tests such as blood cultures to detect pathogens. Treatment is disease-specific: systemic therapies (chemotherapy, targeted therapy, or immunotherapy) for cancer; appropriate antimicrobial therapy for infections.

Relation to other routes:

Hematogenous spread is distinct from lymphatic spread, though some diseases may use multiple routes. Understanding the route informs prognosis and therapy.