Final Diagnosis -- Toxoplasmosis



The immunohistochemical study was positive for Toxoplasma gondii demonstrating positive staining for the bradyzoites within the cysts and pseudo-cysts as well as individual tachyzoites in the necrotic tissue. Histopathological diagnosis of toxoplasmosis could be difficult due to the fact that cysts are difficult to recognize. These cysts may resemble those seen in other infections such as Leishmania donovani, Trypanosoma cruzi, Sarcocystis, Besnoitia and so on (1) Immunohistochemical stains now reveal the true nature of the microorganism, although electron microscopy can be used. Toxoplasmosis is a common CNS infection in AIDS patients (2,3). The characteristic lesion is a necrotizing acute abscess (1). Toxoplasmosis is well known as an intrauterine infection with devastating consequences but it is far more rare in settings outside of these. Although reported in post-transplanted patients, there have been virtually no reports of CNS toxoplasmosis in patients with diabetes mellitus. Only two cases related to patients suffering from diabetes mellitus have been recorded: One case in 1985 was reported in the Portuguese Literature (4) and another case in a Clinical Conference reported by the John Hopkins Hospital (5), the last in a renal-transplanted diabetic patient. Retinochoroiditis due to toxoplasma infection has been described in association with diabetes mellitus and Hepatitis C in HIV-negative patients (6). A case of cerebral toxoplasmosis associated to PML has been described in a patient with no immunodepression (7). Our patient presented a normal blood analysis and no risk factors for AIDS were recorded. Several studies demonstrated that neurons and other CNS cells are HIV-1 target cells (8) The PCR study in the present case did not demonstrate amplification of HIV-1 virus DNA "pol" region. It has been described that nested PCR is an extremely sensitive technique that can detect less than 10 viral copies in crude lysates (9). Zimmerman (10) showed that viral RNA can appear to be detected in only one out of 100,000 non infected cells. RNA viral copies in CNS samples were not demonstrated in this case. We can conclude that our patient has not been infected by HIV, as DNA HIV copies were not found.


  1. Greenfield's Neuropathology. J.Hume Adams, Ed. 6th. Ed Edward Arnold, 1997.
  2. Snider, WD; Simpson DM; Nielsen, S; Glold, W; Metroka, CE; Posner JB. Neurological complications of AIDS: Analysis of 50 patients. Ann Neurol 14: 403-18, 1983.
  3. Zelman, IB; Mossakowski, MJ; Opportunistic infections of the Central Nervous System in the course of Acquired Immune Deficiency Syndrome (AIDS). Folia Neuropathol, 36: 129-44, 1988.
  4. Cavallazzi LO. Toxoplasmosis of the Central Nervous System in a diabetic patient. Arquivos de Neuro-Psiquiatria 43 (3): 319-21, 1985.
  5. Watson AJ; Yang A; Olson JL; Bastacky SI. A 37 year-old man with diabetes mellitus, renal transplant, fever, pulmonary infiltrates and mental status alterations. Clinicopathologic conferences at Johns Hopkins. Maryland Medical Journal 42: 51-9, 1993.
  6. Johnson, MW; Greven, GM; Jaffe, GJ; Sudhalkar, H; Vine, AK. Atypical severe toxoplasmic retinochoroiditis in elderly patients. Ophthalmology. 104(1): 48-57, 1997.
  7. Bertrand, E; Lewadowska, E; Nerurkar, V; Bratosiewicz, J; Yanagihara, R; Zaborski, J; Liberski, PP. Progressive multifocal leukoencephalopathy (PML) and Cerebral Toxoplasmosis in an adult patient with no symptoms of underlying immunosuppressive illness. Folia Neuropathol 36(4): 229-234, 1998.
  8. Price, RW; Brew, B; Sitdi, J; Rosemblum, M; Scheck, AC; Clearly, P. The brain in AIDS: Central Nervous System HIV-1 infection and AIDS dementia complex. Science 239: 586-592, 1988.
  9. Albert, F; Fenyo, EM. Simple sensitive and specific detection of human immunodeficiency virus type 1 in clinical specimens by polymerase chain reaction with nested primers. J Clin Microbion. 18: 1560-64, 1990.
  10. Zimmerman, K; Pischinger, K; Mannhalter, JW. Rapid nonradioactive detection of HIV-1 RNA from a single-cell equivalent by reverse transcription PCR with nested primers. Bio Techniques 15(5): 807-8, 1993.

Contributed by F. Alameda, M. Natcher; MJ. Guardiola, MD, E. Galito, MD, I. Moysset, MD, S. Serrano, MD and F. F. Cruz Sanchez, MD

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