brain abscess in young infants is extremely rare and usually associated with a previous history of bacterial meningitis or septicemia .
here we report a cerebellar abscess mimicking brain tumor with atypical clinical and paraclinical presentations . a two - month
old previously well - baby boy was referred to us with persistent vomiting , strabismus and developmental regression .
the brain imaging showed a right cerebellar mass with multiple small cysts inside the lesion . elevated serum alfa - fetoprotein
associated with cystic and solid posterior fossa mass proposed the preoperative diagnosis of teratoma but tumor cells were not found inside the pathology specimen .
the interest of this case lies in the atypical features of clinical and radiological evaluations in a young infant associated with an abnormal alfa - fetoprotein level of serum .
intracranial mass lesion in early infancy is very rare which may include hemorrhage , infection ( abscess ) , congenital or developmental disorder and brain tumors[1 , 2 ] .
alfa fetoprotein ( afp ) has an important role in the initial diagnostic evaluation as well as in the follow - up of these tumors .
brain abscess is a focal , intracerebral infection that begins as a localized area of cerebritis and develops into the collection of pus surrounded by a well - vascularized capsule .
uncommonly in children , it occurs after infection of a contiguous structure , such as otitis , sinusitis and mastoiditis or as a result of hematogenous spread from a remote site , especially in children with cyanotic congenital heart disease or after meningitis[4 , 5 ] . here
we report a rare cerebellar abscess in a very young infant which mimicked a tumor in laboratory and radiological investigations .
a 2-month old male infant was presented to children 's medical center with enlarging head circumference , persistent vomiting , strabismus and developmental regression since two weeks ago .
he was the second child born from non  sanguineous parents by cesarean section due to being repeated .
he found two and four centimeters head enlargement during the first and second month of life respectively . at admission his vital signs were stable .
the child was irritable with wide and tense fontanel and a setting sun eye was present .
the anterior fontanel was 45 cm wide and the posterior fontanel measured around 1 cm .
he had no prior history of fever , skin infection , ear discharge , trauma or bleeding tendency .
examination of central nervous system did not reveal any cranial nerve palsy or focal neurological deficit except for right side vith nerve palsy and setting sun eye .
cardiovascular and respiratory system were within the normal limits except for small patent foramen ovale that was suggested to be managed conservatively .
hemoglobin was 12mg/100ml , white blood cells count were 12170/mm with 72% polymorphs , 1% band cells , and platelets 300,000/mm .
gr / l ( reference range for this age : 0 - 20 gram / l ) and coagulation tests were normal .
cerebrospinal fluid ( csf ) taken from ventricles was totally normal without high afp level .
brain computed tomography scan revealed left cerebellar hypodense non - homogenous mass with severe hydrocephalus and periventricular edema . magnetic resonance imaging ( mri )
demonstrated a right cerebellar non homogenous mass , which occupied most part of the right cerebellum ; it had cystic and solid components , isointense in t1-weighted and isointense to hyperintense in t2-weighted images with patchy ring enhancement .
the lesion was herniated from the foramen magnum ( figs . 1 , 2 ) .
sagittal view , t1 weighted image reveals hypo to isointense cystic and solid mass of posterior fossa with hydrocephalus .
sagittal view after gadolinium injection shows irregular ring enhancement of the cystic part a cerebellar tumor , most probably teratoma , was thought to be the most likely diagnosis .
a purple gray mass was evident from the surface , no cerebellar cortex was found at the surface .
the mass destroyed all right cerebellar tissue except for the superior surface and extended to the lateral wall of fourth ventricle .
postoperative period was unremarkable except for partial right facial nerve paresis and occasional fever that recovered after one week with antibiotics .
staphylococcus aureus was cultured from the cyst material that was sensitive to vancomycin and amikacin .
treatment was carried out with vancomycin 60 mg / kg in four divided doses and amikacin 15 mg / kg in three divided doses for 4 weeks .
pathological examination revealed granulation tissue , fibrosis , inflammatory infiltration and gliosis without any tumor cells inside the specimen .
hiv elisa and assessment of cellular and humoral immunity to rule out immunodeficiency were normal .
we have reported a young infant with staphylococcal cerebellar abscess that mimicked tumor according to elevated serum afp and neuroimaging .
ring - enhancing lesion in the cerebellum can be inflammatory or neoplastic process which should be differentiated due to different treatment and prognosis .
alfa - fetoprotein is a glycoprotein produced in the embryonic liver , intestine and yolk sac .
the normal half - life of afp is around 4 - 6 days , disappears rapidly after birth and approaches to adult level after about the 10th month of life .
an elevated serum afp strongly suggests the presence of primary liver cancer or germ cell tumor[2 , 3 ] .
brain abscesses include 2 - 5% of intracranial mass lesions , mostly located in the cerebrum but involve cerebellum uncommonly .
the most common causative organisms are gram - negative bacteria ( proteus , klebsiella , citrobacter ) in the first months of life while staphylococcus aureus is rare[36 ] .
usually infant 's status is not good and in spite of all evolution in the diagnosis and treatment the morbidity and mortality are still significant in this age group .
bacteria can reach to the intracranial space through hematogenous spread , meningitis , penetrating trauma , surgery , or local spread from the paranasal sinuses , mastoid air cells or emissary veins[4 , 5 ] .
cerebellar abscess in the children is seen mostly subsequent to otogenic diseases with high mortality and morbidity due to inability to control the infection and posterior fossa compression .
cerebellar symptoms and neurological problems of intracranial hypertension due to 4 ventricle compression are expected signs and symptoms of cerebellar abscess but young infants and neonates may not exhibit these neurological symptoms .
the child was a well baby since two weeks before admission without any history of infection .
the abscess in this patient was an established lesion with severe damage to adjacent cerebellum that could show a long standing infective process and suggest hematogenous spreading of infection at first days of life or even from placenta in the prenatal period .
it can be proposed that bacteria find access to intracranial space through patent foramen ovale . although it is suggested that in young infants breast milk can be a source for staphylococcus related infections .
afp levels 4 or more orders of magnitude above normal range in young infants but the level was more than 10 order of magnitude in this patient .
it is suggested that the afp half life can be longer than normal in some persons specially in low - birth - weight infants which cause higher level of afp in these infants .
there was no history of liver disease or low birth weight and the level of afp decreased significantly after surgery .
so we do not have any explanation for this high level of afp in this rare case of cerebellar abscess .
a young infant with staphylococcus cerebellar abscess is reported which mimicked tumor due to elevated serum afp and neuroimaging .
high afp has not been reported in abscess nevertheless and there is no reason for this high level of afp in this rare case of cerebellar abscess . to find an explanation for this association we propose evaluation of afp in young children with brain abscess .
if this association is justified afp can be considered as a marker to follow the course of the disease .
 backgroundbrain abscess in young infants is extremely rare and usually associated with a previous history of bacterial meningitis or septicemia.case presentationhere we report a cerebellar abscess mimicking brain tumor with atypical clinical and paraclinical presentations . 
 a two - month old previously well - baby boy was referred to us with persistent vomiting , strabismus and developmental regression . 
 the brain imaging showed a right cerebellar mass with multiple small cysts inside the lesion . 
 elevated serum alfa - fetoprotein associated with cystic and solid posterior fossa mass proposed the preoperative diagnosis of teratoma but tumor cells were not found inside the pathology specimen . 
 the culture of the sample was positive for staphylococcus aureus.conclusionthe interest of this case lies in the atypical features of clinical and radiological evaluations in a young infant associated with an abnormal alfa - fetoprotein level of serum . 