Cryptococcoma

Cryptococcomas are a rare complication of infection by the Cryptococcus genus of invasive fungi, where a discrete, encapsulated lesion of immune infiltrates and pathogen forms. Cryptococcus gattii is most often isolated but Cryptococcus neoformans may also form cryptococcomas.

Epidemiology

In general, cryptococcosis occurs secondary to AIDS-related immunodeficiency and so the incidence is higher in countries afflicted by HIV infection, namely Sub-Saharan Africa. Cryptococcus has been isolated, globally ¹. Interestingly, cryptococcoma are more commonly found in the immunocompetent, as Cryptococcus gattii infections are more frequent in healthy hosts ². Case reports of cryptococcoma have been published from a variety of countries, including India, Australia, New Zealand and Uganda ^2-5. 

Clinical presentation

Sporadic infection in the immunocompetent is most often reported ^2,4. The presentation of cryptococcoma depends on which organ is affected - of note, multi-organ involvement may be observed. In the CNS, hydrocephalus and symptoms of raised intracranial pressure are common; pulmonary infection may present with pleuritic chest pain and fever ⁵; a case of intra-abdominal cryptococcoma presented as chronic abdominal pain, intestinal thickening, lymphadenopathy and perforation ⁶.

Diagnosis is made following biopsy, is considered on the basis of multiple lesions consistent with cryptococcosis or assumed in the context of historical cryptococcosis. Interestingly, cryptococcoma formation has been reported to occur following AIDS-associated CNS cryptococcosis and up to 70 days following treatment with both anti-fungal and antiretroviral therapy ³. 

Pathology

Etiology

The two Cryptococcus species implicated in cryptococcoma are Cryptococcus gattii and Cryptococcus neoformans ^7,8. Both species find their natural habitat in the decaying tree bark of a number of tree species and have been isolated from soil, air and avian excreta ⁹. It is thought that human infection occurs following inhalation, penetration of the lung parenchyma and hematological dissemination ⁴. Multiple organs are therefore vulnerable to infection. 

Radiographic features

MRI

• T1: hypointense ^10,4
• T2: hyperintense, with or without vasogenic edema, depending on size ^10,4
• T1 C+ (Gd): contrast-enhancing rim may be seen

Treatment and prognosis

Clinical Practice Guidelines for the Management of Cryptococcal Disease: 2010 recommends fluconazole treatment for 12–18 months, with a minimum course duration of 6 months ⁴. Corticosteroids may be required for the control of surrounding edema, particularly in CNS disease ⁴. Prognosis is poor as lesions may be resistant to treatment, particularly in the immunocompromised ⁴.

Differential diagnosis

CNS lesions can be mistaken for neoplasms, especially in the context of an immunocompetent host ^4,11.