Cerebellar Hypermetabolism in a Hodgkin Lymphoma Leads to Diagnosis of Paucisymptomatic Cryptococcus neoformans Meningitis

Malignancy-associated cerebellar hypermetabolism on [F-18]FDG PET/CT has 2 major causes: paraneoplastic autoimmune encephalitis and neoplasias (leptomeningeal/cerebellar metastases and primary cerebellar tumors). We present the case of a 33-year-old man with a newly diagnosed Hodgkin lymphoma and mere episodical headache, unexpectedly displaying intense cerebellar hypermetabolism on his staging [F-18]FDG PET/CT. Both neurolymphomatosis and paraneoplastic subacute cerebellar degeneration were ruled out by clinical presentation, MR, and repeated lumbar punctures. Instead, cerebrospinal fluid analysis unveiled a Cryptococcus neoformans meningitis, highlighting the possibility of paucisymptomatic central nervous system infections as differential diagnosis in malignancy-related cerebellar hypermetabolism in addition to (para)neoplastic causes.

Automated summary

Malignancy-associated cerebellar hypermetabolism on [F-18]FDG PET/CT can be caused by paraneoplastic autoimmune encephalitis or neoplasias, such as leptomeningeal/cerebellar metastases or primary cerebellar tumors. We present a case of a 33-year-old man with newly diagnosed Hodgkin lymphoma, who unexpectedly showed intense cerebellar hypermetabolism on his staging [F-18]FDG PET/CT despite having only episodic headaches. Neurolymphomatosis and paraneoplastic subacute cerebellar degeneration were ruled out, and cerebrospinal fluid analysis revealed Cryptococcus neoformans meningitis, suggesting that central nervous system infections should also be considered as a differential diagnosis in malignancy-related cerebellar hypermetabolism.