Child 5 years old with suspected arthritis of the knee. Previously, by the patient' s words, was sharply swollen knee, injury denies, previous ultrasound found fluid. At US in the antero-medial distal third of the right femur visualized heteroechoic lesion type of complex cyst with thickened wall, uneven content, with peripheral blood flow at CFM. The narrow isthmus of lesion is lost in the projection of the medial meniscus, the approximate size of the lesion is 4x2,5x6 cm (cyst of the medial meniscus with rupture? else?) In the projection of the same side popliteal fossa visualized enlarged lymph node, with a blood flow at CFM, size of up to 8mm. external link | 
