Pathology Associates Of Lexington, P.A.

Amebae vs. Histiocytes by H&E on Biopsies

Amebae or Histiocytes?

	amebae	histiocytes
size of cell	trophozoites 10-20 microns ave...up to 60 (hematophagic cells tend largest) [an RBC is about 6 & poly about 10]	10-20microns
shape of cell	may be elongated ovals	mostly round to faintly oval
nuclear size	3-4 microns	6-8 microns
nuclear morphology	grayish eosinophilic & poorly visible on H&E; may see punctate central karyosome	basophilic, often pyknotic, & very clearly visible on H&E
cytoplasm	1. usually vacuolated 2. often faintly amphophilic/basophilic on H&E 3. often engulf RBCs, especially if virulent strain 4. PAS may stain brightly pos. & nucleus even less visible than H&E 5. may rarely engulf other debris	1. sometimes vacuolated 2. often eosinophilic by H&E 3. may engulf RBCs not brightly PAS pos. 4.often engulfs other debris such as poly nuclear fragments
other	non-pathogenic types don't engulf RBCs
cases	S-01-14210; S-02-2996	S-00-611; LMC-04-6634
other diagnostic modalities

(posted 13 March 2002; latest addition 3 August 2004)