the trisomy 13 syndrome , also called patau syndrome , was first reported in 1960 . it is a congenital anomaly syndrome caused by accessory chromosome 13 of the d1 group . most patients with this syndrome die soon after birth because of the severe congenital heart disease and brain deformity . 50  % in the first month of life and 90  % during the first year of life . although a few cases of longer survival have been reported [ 3 , 4 ] , there have been no published reports to date on neuropathological findings in long survival cases with trisomy 13 . here , we report an autopsy case of a 7-year - old boy with mosaic type of the trisomy 13 syndrome . this patient was born vaginally after 39  weeks of gestation weighting 3,366  g. he was immediately transported to our hospital because of neonatal aspiration and meconium aspiration syndrome . the boy had systolic heart murmurs and was further diagnosed with ventricular septal defect type iv . he also had several minor anomalies , including capillary hemangioma on forehead , frontal alopecia , narrow v - shaped palate , narrow fingernails , cryptorchidism , inguinal hernia , and penis palmatus . cytogenetic analysis was carried out using a peripheral blood specimen , and the g - banding karyotype analysis revealed the presence of trisomy 13 . fluorescence in situ hybridization ( fish ) assay showed mosaic trisomy 13 : 73.2  % of cultured cells had the karyotype 13 ( 47 , xy  +  13 ) , while the remainder of the cells had normal karyotype ( fig .  1 ) . electroencephalogram showed multifocal spikes ; the convulsions were well controlled by 0.05  mg / kg / day of clonazepam . at the age of 3  years , repeated respiratory infections were seen , so that the boy frequently needed mechanical respiratory support . respiratory problems were eventually controlled by tracheotomy , following which the patient was able to stay at home . at the age of 5  years , the patient could roll over his body and enjoyed touching the toys . physical examination revealed poorly developed and underweight child with respiratory failure . severe aspiration pneumonia developed at the age of 7  years and 4  months , leading to the patient s demise.fig . 1fluorescence in situ hybridization ( fish ) reveals mosaic trisomy 13 , with 73.2  % of cells carrying normal karyotype and 26.8  % trisomy 13 fluorescence in situ hybridization ( fish ) reveals mosaic trisomy 13 , with 73.2  % of cells carrying normal karyotype and 26.8  % trisomy 13 from the age of 6  years , the patient developed aggravated epileptic seizures accompanied by partial convulsions of the left arm . repeated electroencephalogram ( eeg ) spikes in the centroparietal area of the right hemisphere were observed . followed the diagnosis of focal epilepsy , the dose of clonazepam was increased up to 0.1  mg / kg / day which led to cessation of seizures . at the age of 7  years , the drug - induced sleep eeg showed no spikes . on the extremities examination , spastic paralysis of lower extremities and increased deep - tendon reflex were observed . furthermore , neurological examination showed brisk deep - tendon reflexes and a rigid and spastic muscle tone . the examination of the cranial nervous system revealed declined activities of the facial expression muscles , diminished eyelash reflex , and attenuated vomiting reflex . 2a , b ) , and the brain showed relatively good myelination . both left and right lateral ventricles were enlarged , and there were hypoplasia of transparent septum and thinning of the splenium of the corpus callosum . the auditory brainstem response to 100  db revealed prolongation of bilateral i wave latency at 2.9 and 3.0  ms for the left and right side , respectively ( fig . 3a ) . however , the central conduction time and the i  v wave latencies were normal , with no difference between the left and right side of the boy s brain ( 3.8 and 3.7  ms , respectively ) . components of the normal reaction wave were seen on the visual evoked potential ( fig . prolongation was observed in the central conduction time at 7.04  ms ( + 2.8  sd ) upon short - latency somatosensory evoked potential ( fig . 3c).fig .  2 
 a magnetic resonance imaging ( mri ) , t1-weighted , 1.5 t axial view ( se spin echo ; tr  =  15  ms ; te  =  450  ms ) . b the splenium of the corpus callosum is thinfig .  3 
 a the auditory brainstem response to 100  db reveals prolonged wave i latency ( 2.9 and 3.0  ms in the left and right sides , respectively ) . c the short - latency somatosensory evoked potential demonstrates prolonged central conduction time ( 7.04  ms ) 
 a magnetic resonance imaging ( mri ) , t1-weighted , 1.5 t axial view ( se spin echo ; tr  =  15  ms ; te  =  450  ms ) . b the splenium of the corpus callosum is thin 
 a the auditory brainstem response to 100  db reveals prolonged wave i latency ( 2.9 and 3.0  ms in the left and right sides , respectively ) . c the short - latency somatosensory evoked potential demonstrates prolonged central conduction time ( 7.04  ms ) nuclear hypersegmentation and drumstick deformation with club - shaped protrusions were frequently observed in peripheral blood neutrophils ( fig . blood cells were fixed in 1  % osmium tetroxide , dehydrated with ethanol , and embedded in epoxy resin . then , ultrathin ( 100  nm ) sections were prepared and double - stained with uranyl acetate and lead citrate . these specimens were observed using electron microscopy , which revealed small protrusions of neutrophil nuclei , nuclear pockets , and dendritic deformation of the mitochondria ( fig . eosin staining of peripheral blood neutrophils reveals hypersegmentation and drumsticks of neutrophil nuclei ( magnification 100 ) . b electron microscopy ( joel , tokyo , japan ; magnification 100 ) reveals nuclear pockets and dendritic deformation of mitochondria 
 a hematoxylin eosin staining of peripheral blood neutrophils reveals hypersegmentation and drumsticks of neutrophil nuclei ( magnification 100 ) . b electron microscopy ( joel , tokyo , japan ; magnification 100 ) reveals nuclear pockets and dendritic deformation of mitochondria the olfactory bulb , tract , and trigone , and anterior perforated substance were absent , and gyrus rectus showed shape deformation ( fig . 5b).fig .  5 
 a the olfactory bulb , tract , trigone , and anterior perforated substance are absent , and gyrus rectus is abnormally shaped . b coronal section of the autopsied brain demonstrates fenestration of the septum pellucidum 
 a the olfactory bulb , tract , trigone , and anterior perforated substance are absent , and gyrus rectus is abnormally shaped . b coronal section of the autopsied brain demonstrates fenestration of the septum pellucidum histopathologically , each layer of the cerebral cortex was preserved , and polarity of pyramidal cells was intact . the melanin granule was absent in pars compacta of the substantia nigra ( fig . a large number of torpedoes ( swollen axons of purkinje cells ) were seen in the granular layer below the purkinje cell layer ( fig . similar axonal swelling was seen even in the molecular layer , albeit not as extensive ( fig . there were numerous spheroids in the gray matter of the spinal cord and medulla.fig . 6 
 a decreased melanin granule is observed in pars compacta of the substantia nigra ( hematoxylin  eosin staining ; 100 ) . b the presence of characteristic axonal swelling of purkinje cells ( torpedoes ) ( neurofilament ; 100 ) . c similar axonal swelling of purkinje cells is seen in the molecular layer ( bodian ; 200 ) 
 a decreased melanin granule is observed in pars compacta of the substantia nigra ( hematoxylin  eosin staining ; 100 ) . b the presence of characteristic axonal swelling of purkinje cells ( torpedoes ) ( neurofilament ; 100 ) . c similar axonal swelling of purkinje cells is seen in the molecular layer ( bodian ; 200 ) a commonly encountered brain anomaly in trisomy 13 is holoprosencephaly , which is a brain disorder characterized by a failure of differentiation and a various degree of cleavage of the prosencephalon . however , there was no fusion of cerebral hemispheres nor a partial or complete absence of the corpus callosum . however , this diagnosis was not applicable to our patient because of incomplete absence of septum pellucidum . furthermore , the autopsy revealed a relatively well - preserved optic tract . the mortality is generally associated with the severity of deformities in the central nervous system , heart , and respiratory system . to the best of our knowledge , the patient s long survival was due to the absence of complications associated with deformities of major organs , such as the brain , the heart , or the lungs . another unique feature in our case was the presence of numerous torpedoes , i.e. , swollen axons of purkinje cells , within the granular layer . it has been reported in several neuropathologic conditions with diffuse or focal cerebellar changes , such as necrotic lesions , degenerative disease involving the cerebellum , elderly cases of essential tremor , parkinson s disease , alzheimer s disease , cerebellar injury , and aging [ 79 ] . however , this characteristic change in the cerebellum has never previously been reported in autopsy reports on trisomy 13 .
we present here a long survival case of a patient with the mosaic form of trisomy 13 who died of aspiration pneumonia at the age of 7  years and 4  months . 
 the autopsy revealed olfactory aplasia and fenestration of the septum pellucidum , and dilated lateral ventricles and atrophic hippocampus . 
 furthermore , there were numerous  torpedos 
 ( i.e. , swollen fusiform purkinje cell axons ) , mostly in the granular layer underneath the purkinje cell layer , and , occasionally , in the granular layer . 
 similar neuropathological findings have been reported in elderly cases of essential tremor , parkinson s disease , or alzheimer s disease . 
 precise mechanism for this axonal change is still unclear . 
 these pathological changes have never previously been reported in the literature on trisomy 13 , and the present patient is one of the oldest autopsied individuals with the mosaic trisomy 13 .