A newborn male developed diffuse myoclonus. Right frontal craniotomy revealed a thin hemispheric mantle and a cyst communicating with the right lateral ventricle. In the biopsy of the cyst wall there were the characteristic findings of malakoplakia, granulomatous inflammation with von Hansemann histiocytes and Michaelis-Gutmann bodies. The child died at 1 1/2 years of age.