Right parietal cryptococcoma in a young immunocompetent patient: illustrative case.

backgroundCryptococcoma is a rare form of CNS cryptococcosis, typically associated with immunocompromised patients. However, cases reported in immunocompetent individuals have been increasing in recent years and are often initially misdiagnosed. OBSERVATIONS: A 39-year-old previously healthy male patient presented with progressive headache, left-sided hemiparesis, and tonic-clonic seizures. Imaging studies revealed a right parietal expansive lesion with perilesional edema, initially suggestive of a neoplasm. Because of the diagnostic uncertainty, resection of the lesion was performed, and histopathological analysis confirmed the diagnosis of cryptococcoma. The patient received antifungal therapy with amphotericin B and fluconazole and showed improvement in symptoms postoperatively. LESSONS: CNS cryptococcosis presents with variable clinical manifestations depending on the patient's immune status. In immunocompetent individuals, cryptococcomas are primarily characterized by granulomatous reactions. The mean age of incidence is 56 years, and the clinical course tends to be insidious. Etiological diagnosis can be challenging as imaging findings may mimic brain neoplasms, and laboratory tests often have low sensitivity in cases of parenchymal involvement. Thus, resection may be crucial for both diagnosis and treatment. Cryptococcoma should be included in the differential diagnosis of expansive brain lesions, even in immunocompetent patients. Early recognition and appropriate management are essential to prevent complications and improve prognosis. https://thejns.org/doi/10.3171/CASE25713.