Aplasie

Aplasie, or aplasia in English, refers to the absence or defective development of an organ, tissue, or cell line. It can be congenital (present at birth) or acquired later in life. The term is commonly used in medicine to describe situations where an organ or tissue fails to develop normally or ceases to function due to destruction or impairment of its cells. Aplasia is distinct from hypoplasia, which is underdevelopment, and from agenesis, which is a complete absence.

One of the most widely recognized uses is bone marrow aplasia, where the marrow fails to produce enough blood cells, leading to pancytopenia and an increased risk of infection, anemia, and bleeding. The most severe form is aplastic anemia. Other examples include aplasia cutis congenita (absence of skin at birth) and dental aplasia (absent or missing teeth). In many contexts, clinicians distinguish between congenital aplasia and acquired forms caused by injury, drugs, radiation, infections, or autoimmune processes.

Causes can be genetic or environmental and may involve immune-mediated destruction of progenitor cells. Diagnosis typically requires clinical evaluation, complete blood counts showing cytopenias, and, for bone marrow aplasia, a marrow biopsy that demonstrates hypocellularity or other characteristic findings. It is essential to rule out other conditions that mimic aplasia, such as hypoplastic marrow or marrow failure syndromes.

Treatment depends on the organ involved and the underlying cause. For bone marrow aplasia, management includes supportive care (transfusions, infection control), immunosuppressive therapy in selected cases, and hematopoietic stem cell transplantation when appropriate. Other forms of aplasia are treated according to the specific organ system involved and associated conditions. Prognosis varies with cause, severity, and response to therapy.

See also: hypoplasia, agenesis, aplasia cutis, aplastic anemia.