The vessel anatomopathological lesions in a patient with systemic lupus erythematosus associated anti-phospholipid syndrome are described. Vasculitic lesions were nearly absent but small vessels showed hyalin thrombosis or substenosis due to subendothelial deposition of amorphous PAS-positive material in different anatomical districts. These findings can be related to the patient's clinical manifestations, particularly the central nervous system involvement and can be discussed regarding the possible pathogenetic mechanisms.