SIDS "gray zone" disclosed only by a serial sections study of the brainstem and cardiac conduction system.

The SIDS «gray zone» or borderline cases are defined as those cases in which it is difficult to establish if the pathological findings has been sufficiently severe to have caused the death. The complete exam of the brainstem and cardiac conduction system on serial sections in over 100 cases of SIDS, has disclosed 5 SIDS cases in which only our further investigations on the brainstem on serial sections could uncover important anatomo-pathological findings likely representing the morphological substrates for a sudden reflexogenic death. We report a case of discrete T-lymphocytic leptomeningitis of the ventral medullary surface, in a 4-month old female infant dying suddenly and unexpectedly. This infiltrate alone would probably not account for sudden death, but could have had a triggering role. A toxoplasma encephalitis involving the ambiguus nucleus was found in a 1-month-old male infant dying suddenly and unexpectedly. In a 3-month-old boy a tractus solitarius encephalitis was found, not clearly lethal in nature. These three cases are consistent with the triple-risk model of SIDS, an hypothesis consisting of underlying biological vulnerability to exogenous stressors or triggering factors in a critical developmental period. Further studies on triggering factors and related mechanisms will lead to a better understanding of complex interactions involved in the pathophysiology of SIDS. The herein presented case seems to usefully contribute to orient researches in this field. We report an unusual case of benign hemangioendothelioma bilaterally arising from the area postrema invading the medulla oblongata in a 4-month-old male infant dying suddenly and unexpectedly. Post mortem examination was requested with a clinical suspect of SIDS that was confirmed after a complete routinary autopsy. However, an accurate investigation of brainstem on serial sections performed in our institution showed the presence of an hemangioendothelioma. In a SIDS victim a complete exam of the cardiac conduction system on serial sections showed the presence of a Purkinjie cell tumor. Necroscopy studies of sudden infant death should always include an accurate histological examination of brainstem and cardiac conduction system on serial sections but seldom do.