A granuloma is a small collection of immune cells, primarily macrophages, that forms when the immune system attempts to wall off a substance it perceives as foreign or harmful but cannot eliminate. On ultrasound, granulomas can appear as small, echogenic or heterogeneous focal lesions in various organs including the liver, spleen, and lungs. Causes include infections like tuberculosis and fungal disease, foreign body reactions, sarcoidosis, and certain autoimmune conditions. While individual granulomas are often too small to be detected by ultrasound, clusters of granulomas or larger granulomatous masses may be visible and can sometimes be confused with tumors or other focal lesions.
Sonography Term