If immediate surgery is not needed then further testing will be done to determine whether the patient has either macrocephaly or benign macrocephaly. Diagnosis for macrocephaly involves the comparison of the infants head circumference to that of other infants of the same age and ethnicity. If a patient is suspected of having macrocephaly molecular testing will be used to confirm diagnosis. Symptoms vary on the cause of macrocephaly on the child and if the child has any other accompanying syndromes which will be determined through molecular testing. Benign or familial macrocephaly
Benign macrocephaly can occur without reason or be inherited by one or both parents (in which it is considered benign familial macrocephaly and is considered megalencephaly form of macrocephaly). Diagnoses for familial macrocephaly is determined by measuring the head circumference of both parents and comparing it to the childs. Benign and familial macrocephaly is not associated with neurological disorders. While benign and familial macrocephaly does not result in neurological disorders, neurodevelopment will still be assessed. Although neurological disorders do not occur, temporary symptoms of benign and familial macrocephaly include: developmental delay, epilepsy, and mild hypotonia.Neurodevelopment is assessed for all cases and suspected cases of macrocephaly to determine whether and what treatments may be needed, and whether any other syndrome/s may be present or likely to develop. Treatment
Treatment varies depending on whether or not it occurs with other medical conditions in the child and where cerebrospinal fluid is present. If benign and found between the brain and skull then no surgery is needed.
If excess fluid is found between the ventricle spaces in the brain then surgery will be needed. Associated syndromes
Below is a list of syndromes associated with macrocephaly that are noted in Signs and Symptoms of Genetic Conditions: A Handbook. Include multiple major and or minor anomalies
Acrocallosal syndrome
Apert syndrome
Bannayan–Riley–Ruvalcaba syndrome
Cardiofaciocutaneous syndrome
Chromosome 14 - maternal disomy
Chromosome 22qter deletion
Cleidocranial dysostosis
Costello syndrome
Encephalocraniocutaneous lipomatosis
FG syndrome
Hallermann–Streiff syndrome
Hydrolethalus syndrome
Hypomelanosis syndrome
Hypomelanosis of Ito
Kelvin Peter anomaly plus syndrome
Lujan–Fryns syndrome
Macrocephaly-CM (MCAP)
Marshall–Smith syndrome
Neuhauser megalocornea/MR syndrome
Neurofibromatosis type I
Nevoid basal-cell carcinoma syndrome
Noonan syndrome
Ocular-ectodermal syndrome
Osteopathia striata - cranial sclerosis
Perlman syndrome
Robinow syndrome
Simpson–Golabi–Behmel syndrome
Sotos syndrome
Sturge–Weber syndrome
Weaver syndrome
Wiedemann–Rautenstrauch syndrome
3C syndrome

Secondary to a metabolic disorder
Glutaric aciduria type II
GM1 gangliosidosis
Hunter syndrome
Hurler syndrome
MPS VII
Sanfilippo syndrome
Zellweger syndrome

Associated with a skeletal dysplasia
Achondroplasia
Campomelic dysplasia
Craniodiaphyseal dysplasia
Craniometaphyseal dysplasia
Hypochondrogenesis
Hypochondroplasia
Kenny-Caffey syndrome
Kniest dysplasia
Lenz–Majewski syndrome
Osteogenesis imperfecta III
Osteopetrosis, autosomal recessive form
Schneckenbecken dysplasia
Sclerosteosis
Short rib syndrome, beemer-langer type
Short rib-polydactyly 2 (majewski type)
Spondyloepiphyseal dysplasia congenita
Thanatophoric dysplasia

With no obvious physical findings
Alexander disease
Canavan disease
Cobalamin deficiency (combined methylmalonic aciduria and homocystinuria)
Dandy–Walker malformation
Glutaric aciduria type 1
L-2-hydroxyglutaric aciduria
Megalencephalic leukoencephalopathy with subcortical cysts
Osteogenesis imperfecta IV
Osteopathia striata-cranial sclerosis
Periventricular heterotopia
Sandhoff disease
Tay–Sachs disease

See also
Microcephaly
Megalencephaly
Hydrocephalus

References
External links
GeneReviews/NCBI/NIH/UW entry on PTEN Hamartoma Tumor Syndrome (PHTS)
GeneReviews/NCBI/NIH/UW entry on 9q22.3 Microdeletion