Isolated Central Nervous System Relapse After 10 Years in a Case of Primary Testicular Lymphoma Detected on 18F-FDG PET/CT

Abstract

A 51-year-old male patient with a past history of right-sided primary testicular non-Hodgkin lymphoma (NHL) in 2003 was referred to our department with a clinical suspicion of relapse in the brain. The patient was previously managed with bilateral orchiectomy, targeted chemoimmunotherapy with R-CHOP regimen as well as neuroprophylactic chemotherapy with intrathecal methotrexate and cytarabine in 2003. He later started developing episodes of dull headache 10 months back. The patient was referred to our department for 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for restaging purpose. 18F-FDG PET/CT in this patient revealed a metabolically active hyperdense mass (Fig. 1a–g, arrows), involving the corpus callosum as well as the adjacent brain parenchyma on either side associated with peri-lesional oedema, giving an appearance identical to that of a butterfly glioblastoma [1]. There was no evidence of any other focus suggestive of metastasis within the neural axis including the meninges. Also, the rest of the scan was otherwise normal, with no evidence of disease relapse elsewhere. The patient underwent magnetic resonance imaging (MRI) of brain for further characterisation of the brain lesion, which revealed a hypointense, enhancing mass involving the splenium and body of the corpus callosum on either side of the midline with involvement of adjacent brain parenchyma and associated with mild-to-moderate vasogenic oedema suggestive of secondary central nervous system (CNS) lymphoma. Based on the antecedent history of testicular lymphoma and a serum lactate dehydrogenase (LDH) of 394 U/l (125–243 U/l) in this patient, a diagnosis of CNS relapse of the testicular lymphoma was made. As the tissue diagnosis procedure of the brain lesion to assess the clonal variance could not be performed, a distant possibility of a second primary lymphoma affecting the CNS cannot be ruled out in this patient. Subsequently, the patient has been instituted on chemotherapy and the treatment will be subsequently tailored as per the response of the patient to the therapy, which shall be evaluated through periodic PET/CT scans.