The Pediatric Central Skull Base Gary L. Hedlund, D.O. Primary Children’s Medical Center Salt Lake City, Utah

The Chondrocranium Portion of the neocranium formed by endochondral ossification 25 centers of ossification 18 sutures and/or synchondroses Anatomic variants and developmental anomalies abound

Central Skull Base Jinkins JR. Atlas of Neuroradiologic Embryology, Anatomy, and Variants. 2000: LW&W

Newborn Central Skull Base Newborn

Sphenooccipital Synchondrosis NB 3 yrs 5 yrs

Sphenooccipital Synchondrosis 10 yrs 14 yrs

18-year-old female with closed head trauma

Neonatal Central Skull Base Newborn 6 Mo

Craniopharyngeal Canal 5 yrs

Craniopharyngeal Canal Larsen WJ. Human Embryology, 2 ND ed. Saunders; 1997

Craniopharyngeal Canal Courtesy Bronwyn E. Hamilton, MD

Infant Central Skull Base

Age Related T1WI Marrow Changes Newborn 3 yrs 7 yrs

Sphenoid Bone Pneumatization Follows marrow conversion Begins at about 1 – 2 years Reaches the sella by about 7 years Mature by 15 years Asymmetric pneumatization is common Lateral recess pneumatization –Splays distance between f. rotundum & vidian canal

11-year-old boy with headache and lethargy Leukemic marrow infiltration - ALL

Three-year-old with nasal congestion

Diagnostic Considerations? 1.Metastasis 2.Rhabdomyosarcoma 3.LCH 4.Chordoma 5.Chondrosarcoma

Langerhans’ Cell Histiocytosis Denditic cell proliferation Skull (calvarium>orbit>skullbase) –Mandible> ribs> femur> pelvis> spine Imaging –Punched-out, beveled, lack of sclerosis –Sequestration +/- –T1 hyper - isointensity ~ lipid laiden histiocytes –T2 signal variable

Metastatic Disease Leukemia Neuroblastoma Sarcomas –Rhabdomyosarcoma –Soft part sarcoma –Clear cell sarcoma

Seven-year-old female with headache and nasal congestion

Rhabdomyosarcoma Most common childhood soft tissue sarcoma More common in African American children H&N involvement in 50% –Orbit –Parameningeal Nasal cavity, NP, sinuses, parapharyngeal, masticator, pterygopalatine fossa, middle ear –Other Cervical nonparameningeal

Imaging of Rhabdomyosarcoma CT –Bony lysis –ST attenuation MR T1 hypo to isointense T2 hyperintense Variable enhancement

Nonrhabdomyosarcoma Soft Tissue Sarcomas (NRSTSs) Fibrosarcoma Primitive neuroectodermal tumor (PNET) Malignant peripheral nerve sheath tumor Ewing sarcoma Synovial sarcoma

Six-year-old male with chronic headaches

Clival Chordoma Primitive notocord remnant Location –35% skull base –50% sacrococcygeal –15% vertebral body

Clival Chordoma T1WI –Intermediate to low signal –Focal hemorrhage T2WI –High signal intensity –Heterogeneous T1 C+ –Honeycomb enhancement Hemorrhage ~ 30%

Chordoma and TSC TSC is a harmatoneoplastic syndrome Autosomal dominant trait Nonsense mutations in TSC1 (9q34) –Found in: Symptomatic father Clival chordoma of the son Borgel J et al. Eur J Pediatr (2001) 160:138

Fourteen-year-old female with frontal headaches

Kapoor V et al AJNR 23: , March 2002 Neurenteric Cyst

Paraclival Neurenteric Cyst Dysgenesis of notocord & neurenteric canal. Similar to Rathke cleft and colloid cysts Most involve –Craniovertebral junction and posterior fossa Histopathiology –Type A, resemble respiratory or GI epithelium –Type B, smooth muscle, glandular, and lymphoid –Type C, like Type B + glial elements

Summary Review age related ossification and maturation Identify anatomic variants Review anomalies of development Highlight pseudolesions and tumefactions of the central skull base

Thank you