Ectopic Germinoma: A Delayed Diagnosis With Serial Magnetic Resonance Imaging Features.

Mohd Imree Azmi,Nurul Hafidzah Rahim,Sellymiah Adzman,Sarawana Chelwan Muniandy,Yee Ping Ang

doi:10.7759/cureus.20760

Abstract

Germinoma arising from intracranial off-midline structures is considered ectopic. Although basal ganglia germinoma is a rare occurrence, it is more commonly seen in the Asian population, particularly among boys. Here, we report a case of an adolescent boy who presented with hemiplegia and delayed diagnosis of basal ganglia germinoma with progression on serial magnetic resonance imaging (MRI). Several signal changes have been described during the early stage of the disease such as T2-weighted patchy hyperintense signal, cerebral hemiatrophy, and signal change on susceptibility-weighted imaging. 11C-methionine positron emission tomography is an additional imaging technique that can reveal ectopic germinoma. Follow-up MRI revealed small cystic changes, and the latest imaging showed progression into a large multicystic lesion with mass effect. The patient underwent surgery, and histopathological examination revealed basal ganglia germinoma. We highlight the serial MRI changes that were suggestive of basal ganglia germinoma in this case.

Highlights

Intracranial germ cell tumors (GCT) are rare tumors that typically occur in midline structures, namely, the pineal gland and the neurohypophyseal region of the brain
Several signal changes have been described during the early stage of the disease such as T2-weighted patchy hyperintense signal, cerebral hemiatrophy, and signal change on susceptibility-weighted imaging. 11C-methionine positron emission tomography is an additional imaging technique that can reveal ectopic germinoma
Germinoma arising from the basal ganglia is very rare and is considered ectopic with an estimated occurrence ranging between 4% to 20% of all intracranial germinoma

Summary

Introduction

Intracranial germ cell tumors (GCT) are rare tumors that typically occur in midline structures, namely, the pineal gland and the neurohypophyseal region of the brain. We report the case of a patient with a delayed diagnosis of ectopic germinoma with serial imaging findings from the onset of symptoms to a large solidcystic basal ganglia mass. Non-enhanced computed tomography (CT) was normal (Figure 1) On his first magnetic resonance imaging (MRI) in 2017, abnormal signal changes were noted in the left cerebral peduncle and left basal ganglia. There was persistent mild asymmetry of the lateral ventricle, along with a slightly larger left lateral ventricle (not shown) Due to his right-sided hemiplegia and abnormal signal in the left basal ganglia, the patient was diagnosed as having an arterial ischemic stroke. His magnetic resonance angiography (MRA) showed no stenosis or abnormal signals in his intracranial vessels (Figure 3). The fibrovascular septae are infiltrated by lymphocytes. (B) The germinoma cells show membranous staining with CD117 (100×)

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Disclosures