Physiopathology of thyroid cysts in euthyroid nodular goiter.

Following the introduction of echography it has became evident that a large proportion of nodules (15-37%) in euthyroid nodular goiter is entirely or partially cystic (20% in the A. experience). It is thought that cystic areas are subsequent to hemorrhagic necrosis occurring during goitrogenesis and therefore the term "pseudocysts" seems to be preferred. The article summarizes some hypothetical mechanisms of pseudocyst formation. In pseudocysts of recent onset a direct or indirect viral or bacterial etiology is suggested; in longstanding pseudocysts a deficient angiogenesis or immunotoxic mechanisms are proposed.