Contributed by Stephen E. Mason MD,1 Nathaniel D. Dueker MD,2 Charles W. Stratton MD,1 William O. Whetsell, Jr. MD1
1Departments of Pathology
2Radiology, Vanderbilt University Medical Center, Nashville, TN
An 80-year-old man was transferred to our institution with worsening heart failure. His past medical history was significant for Type-2 diabetes mellitus, hypertension, coronary artery disease, chronic obstructive pulmonary disease, emphysema, chronic renal insufficiency and recurrent exacerbations of congestive heart failure. In addition, approximately 5 weeks prior to this admission, he presented at another institution with acute onset of left hemiplegia. Radiographic imaging at the time revealed a right thalamic lesion interpreted to represent acute ischemic changes. He received thrombolytic therapy but showed little improvement in neurological symptoms. He was transferred to a rehabilitation program but there also showed no improvement in neurological symptoms. While in rehabilitation, recurrent heart failure required hospitalization and transfer to this institution. His cardiopulmonary function improved with treatment, but his neurologic status remained unchanged until hospital day ten when he exhibited progressive mental status deterioration. Magnetic resonance imaging (MRI) of the brain showed a ring-enhancing lesion similar to that seen six weeks earlier but now observed to extend into the right basal ganglia and medial temporal lobe with right cerebral hemispheric edema, right-to-left midline shift and asymmetric ventricles (Figure 1, The image has been inverted vertically to correlate with the gross pathologic specimen). These changes were interpreted to be characteristic of a cerebral abscess, but because of the lack of systemic findings, a high-grade intracerebral neoplasm was also considered. Because of his poor clinical status, the patient's family declined a brain biopsy. He died on the eleventh hospital day.
GENERAL AUTOPSY FINDINGS:
An autopsy, performed within 4 hours of death, showed acute bronchopneumonia involving all lung lobes in the setting of marked emphysematous changes. Lung cultures demonstrated coagulase-positive staphylococcus. The examination of the heart showed moderate-to-severe calcific atherosclerosis in all major coronary arteries. There was a remote myocardial infarction involving the anterior left ventricular wall and the anterior two-thirds of the interventricular septum, extending from apex to base.
NEUROPATHOLOGIC AND MICROBIOLOGIC FINDINGS:
Gross examination of the brain demonstrated generalized cerebral edema and mild uncal grooving bilaterally. At the time of autopsy, the right parietal lobe was incised sterilely to reveal a 3.5 cm gray-white, hemorrhagic abscess cavity with shaggy walls in the right cerebral deep white-matter and right basal ganglia (Figure 2). This cavity contained green-gray necrotic debris and purulent material. Fungal and bacterial cultures were taken. Subsequent examination of the formalin-fixed brain showed this cavity to extend into the anterior thalamus with multiple sub-centimeter satellite lesions. Microscopic examination of hematoxylin and eosin stained sections of the abscess cavity showed abundant pigmented fungal hyphae invading the surrounding brain tissue (Figure 3). Gomori methenamine silver stain highlighted the irregularly swollen hyphae and conidia and demonstrated vascular invasion (Figure 4).
Microbiological studies revealed moderate growth of a black mold with a velvety appearance on Sabouraud's dextrose agar. There was good growth at 30, 37 and 42 degrees Celsius. Both the surface and the reverse side of the plate appeared jet-black (Figure 5). Dissecting microscope exam of the plate showed hyphae made up of sparsely branched wavy chains of smooth oval conidia branching at several angles.