Table 1.

Differential diagnosis of amoebic encephalitis by histopathologic features

	Present case	Balamuthia mandrillaris	Acanthamoeba spp.	Naegleria fowleri
Trophozoite
Size (µm)	20–25	12–60	15–50	10–25
Nuclei	1–2	1–3	1	1
Nucleoli	1–4	≥ 1	1	1
Cyst
Size (µm)	15–20	15–30	15–25	Not identified
Double layer wall
Outer	Wavy	Wavy	Wrinkled	Not identified
Inner	Round	Round and rigid	Various shape	Not identified
Background	Acute inflammation	Acute to granulomatous inflammation (GAE)	Granulomatous inflammation (GAE)	Acute inflammation (PAM)
	Angiitis	Angiitis	Angiitis
CSF study	Not done	Not identified	Usually absent (if present, in trophozoite form)	Present, in flagellate form
Others			Keratitis
			Skin infection

GAE, granulomatous amoebic encephalitis; PAM, primary amoebic meningoencephalitis; CSF, cerebrospinal fluid.