CASE 10839 Published on 26.03.2013

Simultaneous abdominal histoplasmosis and cerebral toxoplasmosis in an AIDS patient

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Quaglia FM, Rossi P, Cosottini M, Caramella D, Bartolozzi C.

Diagnostic and Interventional Radiology,
University of Pisa, Italy.
Patient

24 years, male

Categories
Area of Interest Abdomen, Neuroradiology brain ; Imaging Technique CT, MR
Clinical History
A 24-year-old transsexual man, with a history of HIV infection, presented with fever, weight loss, flank pain and hepatosplenomegaly. His tendon reflexes were exaggerated. He had a deficit of the VII right cranial nerve and dysarthria.
Imaging Findings
Abdominal CT (Fig. 1) showed a hypodense mass around the hepatic ilus. There were multiple mesenteric and retroperitoneal lynphoadenopathies suspect for lymphoproliferative disorder. Laparoscopic biopsy revealed granulomatous mesenteric lymphadenitis due to histoplasma capsulatum.
Bacause of the neurological symptoms cerebral CT (Fig. 2) was performed showing a spheric hypodense lesion in the left globus pallidus. MRI (Fig. 3) showed a hyperintense lesion with hypointense core on T2-W images, with periferal ce on T1-W images, suggestive of toxoplasmosis, but clinicians started the administration of Itraconazole and Amphotericin B, as if cerebral histoplasmosis. There was improvement of the abdominal disease (Fig. 4) but cerebral images showed enlargement of the prior lesion and appearance of another one with the same imaging features in the right medial frontal gyrus (Fig. 5). Administration of anti-toxoplasma therapy (Pirimetamin and Atovaquone) determined improvement of neurological conditions and reduction in lesions size on TC images (Fig. 6).
Discussion
Histoplasmosis is an opportunistic fungal infection, common in patients with advanced AIDS. It is caused by inhalation and haematogenous spread of histoplasma capsulatum (found in pigeon and bat feces) [1]. Malaise, fever and cough are common clinical presentation. In patients with disseminated histoplasmosis the abdomen is commonly affected, but abdominal Histoplasmosis is rarely recognised clinically due, in part, to nonspecific manifestations like abdominal pain, moderate hepatosplenomegaly and weight loss [2]. Central Nervous System (CNS) involvement is recognised in 5%-10% of cases of disseminated histoplamosis and results in diffuse meningitis or in focal granuloma/abscess formation [3]. Identification of specific organism is needed for diagnosis but imaging can be useful too. Best diagnostic clue are meningeal enhancement or enhancing non-specific ring-like appearing lesions in brain and/or spinal cord in immunosuppressed patient. If treatment (Itraconazole and Amphotericin B) is delayed for more than 2 weeks, prognosis is poor [1].

Another opportunistic infection that occurs in immunocompromised, especially HIV+ patients, is acquired toxoplasmosis. CNS toxoplasmosis affected 3-40% of AIDS population and is the most common cause of focal lesion in HIV+ [4]. Toxoplasma Gondii is an obligate intracellular protozoan which can cause necrotising, organising or chronic abscess. Toxo-encephalitis has an initial focus in a parenchymal abscess with necrosis and surrounding inflammation [1].
CT findings are hypo/iso dense lesions, usually with surrounding oedema and mass effect with thin, smooth rim or solid nodular enhancement.
The best imaging tool is MR which shows:
• Solitary or multiple lesions, most common acutely, with nodular or ring enhancement often with surrounding hypointensity (oedema) on T1-W images. These enhancing lesions are most common in periventricular white matter and in basal ganglia.
• Multiple hypointense foci on T2 often with an eccentric target sign.
• DWI restriction variable: often lesions lack restricted diffusion, unlike most abscesses.
• Basal ganglia calcification, especially post-therapy.
Response to specific therapy (Pyrimethamine and Atovaquone) is high (70-95%) but it is also Highly Active AntiRetroviral Therapy that improves prognosis [1].
Differential Diagnosis List
Cerebral toxoplasmosis in a HIV+ patient with abdominal histoplasmosis
Ring-enhancing solitary lesions in HIV+ patients:
Metastases
Glioblastoma multiforme
Abscess
Intracerebral haematoma
Neurocysticercosis
Primary CNS Lymphoma
Fungal and Parasites diseases
Tuberculosis
Final Diagnosis
Cerebral toxoplasmosis in a HIV+ patient with abdominal histoplasmosis
Case information
URL: https://www.eurorad.org/case/10839
DOI: 10.1594/EURORAD/CASE.10839
ISSN: 1563-4086