Rare Case of CNS Toxoplasmosis Seen in Patient With Myasthenia Gravis

A patient with myasthenia gravis (MG) who presented with a rare case of central nervous system toxoplasmosis was the subject of a recent report in ID Cases.

The 78-year-old male presented to an emergency department (ED) in Iowa with an altered mental status, and he was found to have a medical history of non-Hodgkin’s lymphoma and MG, for which he was taking chronic mycophenolate mofetil (MMF). He also had a history of coronary artery disease and type 2 diabetes.

“Cerebral toxoplasmosis has been rarely reported in patients with hematologic malignancies or in those receiving immunosuppressive agents,” the report’s authors wrote.

The current case emphasizes the need for “a high degree of suspicion for T gondii in individuals who do not have HIV and are on immunosuppressants drugs including MMF,” they added.

T gondii, a parasitic infection, was a key pathogen during the 1980s HIV/AIDS pandemic and can exist in skeletal muscle, the eyes, and brain, and in cyst form.

The patient underwent 6 cycles of chemotherapeutic treatment for B-cell lymphoma, which he completed 6 months before his current presentation. Repeat CT showed a near complete resolution of his lymphoma, the authors wrote.

Three weeks before the presentation, the patient also began having right-sided visual hallucinations, according to his wife. Following a steady worsening of his condition, he was taken to the ED where he had a dry cough, was vomiting, and had a temperature of 100.5 °F.

“A noncontrast CT scan of the head showed a large area of evolving cerebral infarcts with involvement of the left frontal, parietal, and occipital lobes; there was no intracranial hemorrhage,” the researchers said. An MRI of the brain was subsequently carried out and showed lesions in both the left frontal and occipital lobes.

He began taking intravenous dexamethasone and was thought to have metastatic lymphoma to the brain. The patient’s MMF for MG was also reduced at this time.

Once in a tertiary care unit, he underwent an image biopsy and microscopic examinations that revealed “microorganisms consistent with Toxoplasma gondii,” the authors wrote. Serum testing for T gondii also turned up positive.

He began treatment with oral pyrimethamine, sulfadiazine, and leucovorin, along with levetiracetam for seizure prophylaxis. The patient’s mental state began to improve following treatment for toxoplasmosis.

He was eventually discharged to a rehabilitation facility but began to regress and sustained a fall.

Two months following his initial diagnosis, he presented again to an ED with an altered mental status. At this time, “a CT scan of the brain showed worsening chronic subdural hematoma, which was likely the cause of the patient’s acute cognitive decline.”

While in the hospital, he had pneumonia, a Clostridioides difficile colitis infection, myocardial infarction, and persistent pancytopenia, but he was eventually discharged. However, 2 months later he returned with increasing weakness and was eventually intubated and put on mechanical ventilation. He was ultimately transitioned to comfort care and died 5 months after his initial diagnosis.

“While our patient did not have HIV/AIDS, he was on high-dose immunosuppressant medication, which is a risk factor for reactivation of latent T gondii,” the authors wrote. In addition, “his history of extranodal unclassified B-cell lymphoma complicates his immune status.”

Fewer than 10 cases implicating MMF in cerebral toxoplasmosis development among patients without HIV have ever been published, they added.

Overall, “more studies need to be done to ascertain optimal testing strategies in this population and to evaluate the utility of chemoprophylaxis in the prevention of reactivation,” the researchers concluded.

Reference

King R, Sekar P, Patel H, et al. CNS toxoplasmosis, a rare presentation in a patient with Myasthenia Gravis. IDCases. Published online May 16, 2023. doi:10.1016/j.idcr.2023.e01780