PMC3646452_01
A. Diagram of the structure of human arachnoid granulation (from, with permission). B. Diagram illustrating position of the arachnoid granulations between the sub arachnoid space and venous sinus. C. High power view of normal arachnoid granulation from a patient dying of unrelated cause (H&E stain). D and E (high power). Case 1. Arachnoid granulation with large numbers of cryptococcal cells (arrowed) and little inflammation. Mucicarmine stain. F. Case 1. Brain tissue showing cryptococcal cells (arrowed) invading brain adjacent to a blood vessel. Mucicarmine stain. Note the paucity of organisms in the brain tissue compared to the arachnoid granulations.
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F1
The arachnoid granulations contained numerous cryptococcal cells (mean 286 /highpower field, range 96-589) with very little inflammatory reaction (Figure 1).
PMC3646452_02
A. (mucicarmine stain) and B. (high power, elastic Von Gieson stain, which stains collagen pink) Case 2. Arachnoid granulation with cryptococci (arrowed), necrosis, and fibrosis. The channels within the granulation appear compressed.. C. Case 4. Electron microscopy of an arachnoid cell containing two cryptococcal cells (short arrows) with large capsules (dashed arrow). Vacuoles within the cell contain material of the same electron density as the cryptococcal capsule (long solid arrrows).. D. Case 4. Cryptococcal cells (arrowed) in the brainstem. Mucicarmine stain
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F2
Electron microscopy showed encapsulated yeasts within arachnoid cells, which also had vacuoles that appeared to contain cryptococcal polysaccharide (Figure 2C). Of note was the invasion of pons and midbrain by cryptococci, without an inflammatory response (Figure 2D).
PMC3646452_03
PMC3646452_04
A. (mucicarmine stain) and B. (high power, elastic Von Gieson stain, which stains collagen pink) Case 2. Arachnoid granulation with cryptococci (arrowed), necrosis, and fibrosis. The channels within the granulation appear compressed.. C. Case 4. Electron microscopy of an arachnoid cell containing two cryptococcal cells (short arrows) with large capsules (dashed arrow). Vacuoles within the cell contain material of the same electron density as the cryptococcal capsule (long solid arrrows).. D. Case 4. Cryptococcal cells (arrowed) in the brainstem. Mucicarmine stain
emss-30466-f0002.jpg
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F2
Electron microscopy showed encapsulated yeasts within arachnoid cells, which also had vacuoles that appeared to contain cryptococcal polysaccharide (Figure 2C). Of note was the invasion of pons and midbrain by cryptococci, without an inflammatory response (Figure 2D).
PMC3646452_05