Pineoblastoma: A case of good response to radiotherapy

Clinical History

A 43-year-old gentleman presented with neurological symptoms and CT of the head was abnormal with signs of hydrocephalus. Endoscopic third ventriculostomy relieved the pressure symptoms of hydrocephalus and biopsy confirmed the diagnosis. Further neurosurgery was not possible and the patient underwent radical radiotherapy with good response.

Imaging Findings

The differential diagnosis of masses in the region of pineal gland includes (their distinguishing radiological features are given in brackets) [1];

• Pineal cyst (well circumscribed fluid density lesions)

• Primary Pineal tumours (radiological features vary depending upon grade of the lesion. Low grade pineocytomas are better defined and high grade pineoblastomas are poorly defined. As these originate from pineocytes, the masses are usually calcified)

• Germ cell tumours (contrast enhancing soft tissue density masses and intrinsic calcification is uncommon, these tend to engulf normal pineal gland calcification)

• Secondary metastases (in the majority of cases there is evidence of primary disease elswhere)
• Vascular lesions (radiographically distinct lesions with no soft tissue mass effect with possible associated dilated vessels or vascular aneurysms)

Discussion

A 43-year-old previously fit and healthy gentleman presented with progressively worsening symptoms of early morning headaches, nausea, dizziness and vision blurring. CT examination showed space occupied lesion. MRI revealed enhancing pineal mass with signs of hydrocephalus. He underwent endoscopic third ventriculostomy, and a biopsy was taken. Symptoms of hydrocephalus resolved and the pathology confirmed WHO grade IV Pineoblastoma (Ki67 >40%).

Futher surgical resection was not feasible due to operative risks. MRI of the spine did not show any abnormality and lumber puncture revealed highly suspicious for malignant cells – Chang stage M3. Serum tumour markers, AFP and HCG levels were normal. A diagnosis of high grade pineoblastoma was made and the patient was offered craniospinal irradiation. He received 40.8 Gray in 24 fractions to cranio-spinal axis and 15.3 Gray in 9 fractions as a boost to the pineal tumour. He developed alopecia and grade 1 scalp erythema. Soon after completion of his tumour, he was admitted with sepsis secondary to bilateral pneumonias which was treated accordingly. He made a full recovery. Post treatment, he was also found to have low cortisol and increased ACTH levels. Endocrinology opinion was obtained and it was felt that the picture was consistent with partial hypoadrenalism likely secondary to exogenous use of steroids. There was no significant evidence of hypopituitrism. He was commenced on steroid replacement and recovered very well. Repeat MRI three months after completion of radiotherapy showed good response to the treatment.

Pineal region tumours are rare, <1% of all intracranial tumours (in children, 3-8%) [2]. Germ cell tumours are more common in this region. Pineocytomas are more common than Pineoblastoma, which are extremely rare. Maximum possible surgery is treatment of choice. Radiotherpay is used adjuvantly and radically in case of residual disease post surgery [3]. In case of metastasis (like in this case as CSF was positive for malignant cells), craniospinal irradiation (CSI) is treatment of choice. It is associated with side effects e.g. tiredness, emesis, skin reaction, alopecia, bone marrow suppression, headaches, sleep and memory disturbance. It can also affect the pituitary function due to some unavoidable dose to the pituitary gland. The patient needs to be under regular follow up with surveillance images. The prognosis depends on histological type, size of the tumour and extent of disease at presentation [4]. Surgical resection followed by adjuvant radiotherapy results in median survival of 20 months [2].

Differential Diagnosis List

Final Diagnosis

Pineoblastoma

URL:	https://eurorad.org/case/10128
DOI:	10.1594/EURORAD/CASE.10128
ISSN:	1563-4086