Expansive cerebral lesion caused by cryptococcus in an immunocompetent patient: a diagnostic challenge

Abstract

Case Presentation: A 62-year-old patient, previously healthy and immunocompetent, presented with speech difficulty that began three weeks earlier, characterized by slowed speech and word-finding difficulty, associated with reduced strength in the right hemibody. On neurological examination, the patient showed mild motor aphasia, grade IV right hemiparesis, and increased ipsilateral deep tendon reflexes, without meningeal signs. Laboratory tests showed leukocytosis (11,200/mm³) with neutrophil predominance, elevated C-reactive protein (1.8 mg/dL), and preserved renal and hepatic function. Serology for HIV and hepatitis B and C was negative. Brain magnetic resonance imaging revealed an intra-axial expansive lesion in the left frontal lobe, with heterogeneous peripheral enhancement after contrast and mild adjacent vasogenic edema. The patient underwent surgical resection of the lesion. Histopathological examination showed a granulomatous inflammatory process with encapsulated yeasts compatible with cerebral cryptococcoma. In the postoperative period, lumbar puncture was performed, revealing clear cerebrospinal fluid, normal opening pressure, cellularity of 12 cells/mm³ (predominantly lymphomononuclear), protein level of 68 mg/dL, and glucose of 58 mg/dL. Cryptococcal antigen testing in the CSF was positive, with negative culture. Treatment with amphotericin B was administered for 23 days, with favorable clinical evolution and progressive improvement of motor and language deficits. The patient was discharged for outpatient follow-up in infectious diseases and neurology. Discussion: Cryptococcoma is an uncommon manifestation of Cryptococcus infection, consisting of an encapsulated lesion composed of immune infiltrate and pathogen. Its most frequent locations are the basal ganglia, thalamus, and cerebellum. In the central nervous system, it may mimic neoplastic diseases or pyogenic abscesses; therefore, clinical history, contrast-enhanced magnetic resonance imaging, and cerebrospinal fluid analysis with cryptococcal antigen testing are the main diagnostic tools. Although more frequently associated with immunocompetent individuals, serologic testing for HIV and other causes of immunosuppression is necessary. Early recognition is essential because this infection has been associated with neurological sequelae, the need for neurosurgical intervention, and delayed or inadequate therapeutic response. Treatment includes induction therapy with amphotericin B for 4–6 weeks, followed by a consolidation phase with antifungal agents for a prolonged period, which may be guided by serial neuroimaging. Reduction of edema with glucocorticoids, aggressive management of intracranial pressure, and surgical resection when feasible are also important components of therapeutic management. Final Comments: This case highlights the importance of considering cryptococcoma in the differential diagnosis of expansive lesions of the central nervous system, even in immunocompetent patients, to avoid diagnostic and complications.