Lymphocytic thyroiditis appears most frequently in the form of hypoechogenic discrete lesions within an echonormal or moderately hypoechogenic background. The usually multiple, discrete areas present a not regularly geometrical shape. The differentiation of these lesions from nodules in a pathological sense are the greatest challenge in thyroid ultrasound. The ultrasound differentiation may be easy as demonstrated in the first and second rows of images but may be impossible as demonstrated in the last row of images.