[Pulmonary nocardiasis with abscesses spreading to cerebrum, cerebellum and orbits]

Subtentorial cerebral nocardiosis in immunocompetent patients: CT and MR imaging findings

PURPOSE

To describe the clinical presentation and computed tomography (CT) and magnetic resonance imaging (MRI) appearances of subtentorial nocardia cerebral abscesses developing in immunocompetent patients.

PATIENTS AND METHODS

The clinical findings and the results of CT and MRI examinations of three immunocompetent patients with nocardiosis located initially only in the subtentorial region were studied. Three patients underwent CT examination and two patients had MRI.

RESULTS

Clinically, two patients had cerebellar syndrome and the third had meningism with fever. The diagnosis of nocardiosis was bacteriologically confirmed by demonstrating the organism in lumbar puncture fluid in one patient and by an aspiration biopsy of the abscess in the other two. Two of the patients improved under targeted antibiotic therapy whereas the third patient died. The main imaging features of the lesions were a multiloculated appearance with peripheral enhancement after intravenous administration of iodinated contrast material on CT and a multicystic appearance on MRI, with a peripheral hypointense rim on T2-weighted images, a relatively minor mass effect and a multiloculated appearance on gadolinium-chelate enhanced T1-weighted images.

CONCLUSION

The clinical presentation of cerebral nocardiosis is relatively non-specific. A microcystic lesion surrounded by hypointensity on T2-weighted MR images with a multiloculated pattern after gadolinium chelate administration on T1-weighted MR images in association with a relatively minor mass effect should suggest this diagnosis even if the lesion is single and in the absence of immunosuppression.

[Infections in organ transplantations]

Infections play a crucial role in organ transplantations as possible complications. Viruses, bacteria, fungi and parasites are potential agents. The relevance of individual diseases depends on the organ transplanted. Morphology of the inflammatory reaction is given by the agent involved, but often several reactions can be caused by the same agent and different agents can also lead to the same reaction. Histology therefore provides concrete identification of the causal agent only in some cases, such that additional microbiological diagnostics are necessary. Results from these investigations should be transferred to the pathologist to distinguish between infection-associated changes and transplant rejection.

Cerebellar nocardiosis and myopathy from long-term corticosteroids for idiopathic thrombocytopenia

Infection of the central nervous system with Nocardia sp. usually manifests as supratentorial abscesses. Supratentorial and cerebellar abscesses from infection with Nocardia sp. following immunosuppression with long-term corticosteroids for idiopathic thrombocytopenia (ITP) have not been reported. An 83 years-old, human immunodeficiency virus (HIV)-negative, polymorbid male with ITP for which he required corticosteroids since age 53 years developed tiredness, dyspnoea, hemoptysis, abdominal pain, and progressive gait disturbance. Imaging studies of the lung revealed an enhancing tumour in the right upper lobe with central and peripheral necrosis, multiple irregularly contoured hyperdensities over both lungs, and right-sided pleural effusions. Sputum culture grew Nocardia sp. Neurological diagnostic work-up revealed dysarthria, dysphagia, ptosis, hypoacusis, tremor, dysdiadochokinesia, proximal weakness of the lower limbs, diffuse wasting, and stocking-type sensory disturbances. The neurological deficits were attributed to an abscess in the upper cerebellar vermis, myopathy from corticosteroids, and polyneuropathy. Meropenem for 37 days and trimethoprime-sulfamethoxazole for 3 months resulted in a reduction of the pulmonary, but not the cerebral lesions. Therefore, sultamicillin was begun, but without success. Long-term therapy with corticosteroids for ITP may induce not only steroid myopathy but also immune-incompetence with the development of pulmonary and cerebral nocardiosis. Cerebral nocardiosis may not sufficiently respond to long-term antibiotic therapy why switching to alternative antibiotics or surgery may be necessary.