Clinical, pathologic, and imaging characteristics of PMA and PA^*

	PMA	PA
Pathology	Monomorphous piloid cells with myxoid background angiocentric pattern	Heterogeneous/mixed piloid and protoplasmic cells
	Rosenthal fibers, eosinophilic granular bodies, and microcalcifications rare1,2	Rosenthal fibers, eosinophilic granular bodies, and microcalcifications common1,2
Clinical
	Infants, children, and adults3	Young children and, less commonly, adults3
	More aggressive	Less aggressive
	Less progression-free and overall survival	Greater progression-free and overall survival
	More recurrences3	Fewer recurrences3
	Most common location: hypothalamus/optic chiasm17	Most common location: posterior fossa17
	May be associated with NF-19,10	May be associated with NF-110
Imaging
	Hypointense T1	Hypointense T1
	Hyperintense T2/FLAIR5	Hyperintense T2/FLAIR5
	Variable contrast enhancement5	Variable contrast enhancement5
	Solid with central necrosis5	Often cystic5
	Calcification (<10%)5	Calcification (10%)5
	Intratumoral hemorrhage common (12%–25%)8,16,32,33	Intratumoral hemorrhage less common (∼8%)29

^*Although PMA is most commonly found in the hypothalamic/chiasmatic region, because of its rarity, an undiagnosed hypothalamic/chiasmatic tumor is most likely to be the more common PA.