A 27-year-old immunocompetent agricultural worker presented chronic meningitis and
hydrocephalus. Despite CSF and systemic investigation no etiology was defined. Spastic
paraplegia installed 15 years later. Spinal and brain MRI are displayed in [Figures 1] and [2]. The patient developed intracranial hypertension and died days later. A diagnosis
of histoplasmosis was made at autopsy ([Figure 3]).
Figure 1 Thoracic spine MRI. A) Sagittal T2 weighted image showing a low signal central lesion
in the spinal cord at T7 level, with associated edema above and below. Sagittal T1
weighted images before (B) and after contrast administration (C) and axial after contrast
(D) demonstrate its nodular enhancement.
Figure 2 Brain MRI. A and B) axial T2 weighted images demonstrate low signal lesion located
at the anterior horn of the right lateral ventricle (arrow) and another isointense
lesion located at the right foramen of Monroe, which suggested the possibility of
a granulomatous process. Axial T1 weighted images before (C) and after contrast administration
(D) demonstrate its nodular enhancement.
Figure 3 A) Coronal section through brain showing hemorrhagic lesion distending the third
ventricle. There is also dilatation of lateral ventricles by blood clots. B) Small
subependymal lesion in anterior horn of right lateral ventricle with central caseous
necrosis surrounded by thick fibrous capsule and lymphocytic infiltrate. This may
have been the entry site for histoplasmas in the brain (primary histoplasmoma). HE,
X 40. C) Macrophage in the third ventricle lesion containing abundant microorganisms
with features of Histoplasma sp. HE, X 400. D) Small artery in third ventricle wall
surrounded and delaminated by parasite filled macrophages. Vasculitis may have caused
intraventricular hemorrhage. HE, X 100. E) Histoplasma sp. in macrophage phagosome
as small regular yeast forms. Nearly all parasites were intracellular. Grocott’s methenamine
silver, HE counterstain, X 400. F) Ultrastructure of Histoplasma sp. in a phagocytic
cell. Numerous electron dense viable fungi often with a pale vacuole, surrounded by
electron lucent capsule. Electron microscopy, X 2500.
Histoplamosis as isolated central nervous system disease is rare, being more common
in immunosuppressed patients[1],[2]. As in this case, it can be a challenging diagnosis, and should be considered in
any brain or spinal cord lesion with granulomatous pattern.
