Tissue disease, also known as histiocytosis, is an umbrella term that refers to a group of diseases characterized by an accumulation of abnormal cells—called histiocytes—in the body’s tissues and organs. Histiocytes form when the immune system malfunctions and produces too many of these cells, leading to inflammation and tissue damage. Tissue disease can be caused by genetic factors, or by an overactive immune system in response to factors such as inflammation, infections, and toxins. Common symptoms of tissue disease can include fatigue, anemia, weight loss, and organ damage. Left untreated, tissue diseases can have serious long-term consequences, making early diagnosis and treatment essential for long-term health.

See also: immune system, mycorrhizal system, narrative, ecosystem