case_images: PMC11333125_01
case_images: Magnetic resonance images. (A) T2-weighted midsagittal plane. (B) T2-weighted transverse plane and (C) T2-weighted FLAIR transverse plane at the level of the aqueduct. (D) T1-weighted midsagittal fat-saturated postcontrast plane. (E) T1-weighted transverse fat-saturated postcontrast plane. The MRI reveals CSF flow obstruction at the level of the aqueduct (green arrow) with no discernible cause. Additionally, transtentorial herniation with flattening of the rostral aspect of the cerebellum and foramen magnum herniation with associated cervical syringomyelia (green star) were observed, likely attributed to increased intracranial pressure. CSF = cerebrospinal fluid; FLAIR = fluid-attenuated inversion recovery; MRI = magnetic resonance imaging.
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case_images: fig1
case_images: Tesla unit (Siemens Medical Solutions USA, Inc., Malvern, Pennsylvania), and multiple sequences were acquired, including T2-weighted, proton density (PD)-weighted images, T2-weighted-fluid-attenuated inversion recovery (T2-FLAIR), diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps, and susceptibility weighted imaging (SWI). Multiplanar reconstruction of T1-weighted, fat-saturated images pre and postintravenous contrast mediums was obtained. The findings revealed obstructive hydrocephalus at the level of the mesencephalic aqueduct (Figure 1).
case_images: Postmortem examination, heart. (a) Grossly, the heart is enlarged and discolored white tan. (b) Histologically, the heart is infiltrated and largely replaced by algae and associated necrosis and inflammation. Endosporulation is evident; endospores are occasionally arranged in a radial tripartite configuration ("Mercedes-Benz" endospores; arrow) consistent with Prototheca; hematoxylin and eosin (H&E), 400x; inset-H&E, 600x.
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case_images: fig2
case_images: Algal organisms were most numerous in the heart and brain (Figures 2, 3, and 4), and these organs had an associated inflammatory infiltrate composed of lymphocytes, plasma cells, and macrophages. Many had undergone endosporulation (Figure 2), in which the sporangia had wedge-shaped, radially arranged, angular endospores (daughter cells) divided by septations.
case_images: Brain histology. Algae and associated inflammation line and bulge into ventricles; H&E, 20x and 200x (inset).
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case_images: fig3
case_images: Algal organisms were most numerous in the heart and brain (Figures 2, 3, and 4), and these organs had an associated inflammatory infiltrate composed of lymphocytes, plasma cells, and macrophages.
case_images: Brain histology. Algae infiltrate and expand the choroid plexus; H&E, 200x.
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case_images: fig4
case_images: Algal organisms were most numerous in the heart and brain (Figures 2, 3, and 4), and these organs had an associated inflammatory infiltrate composed of lymphocytes, plasma cells, and macrophages.
case_images: Heart histology. (A) Organisms stain positively with Grocott's methenamine silver and (B) periodic acid-Schiff with diastase, compatible with Prototheca infection.
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case_images: PMC11333125_01_CRIVEM2024-1402828.005.jpg
case_images: fig5
case_images: Moreover, organisms stained with Grocott's methenamine silver (GMS), periodic acid-Schiff (PAS), and periodic acid-Schiff with diastase (PAS-D) (Figure 5). Whereas Chlorella has PAS-positive diastase-sensitive cytoplasmic starch granules, our test confirmed that the organisms in this case were PAS-positive with diastase-resistant endospores, consistent with Prototheca spp. (Figure 5).