DIAGNOSIS: DIFFUSELY INFILTRATING GERMINOMA
ADDITIONAL TREATMENT AND CLINICAL PROGRESS:
After the lesion was diagnosed as a germinoma, the patient was treated with whole brain irradiation in fractions of 1.6 Gy, to a total dose of 44.8 Gy. Follow-up MRI showed disappearance of the enhancement and her condition improved, although focal deficits remained present. Three years after treatment she had a relapse which was treated with chemotherapy (bleomycin-etoposide-cisplatin) with good respons. One year later a second relapse occurred.
Germinomas are tumors of germ cell origin and represent the brain counterpart of testicular seminoma. They are relatively rare and represent 0.4-3.4% of all primary intracranial tumors, although in Northeast Asia this is significantly higher, up to 9% (4). Like other extragonadal germ cell tumors, germinomas occur primarily in the midline, with the region of the pineal gland being the most common site, followed by the suprasellar compartment (8). They occur predominantly in children with a peak incidence around 12 years of age (4).
Depending on anatomical localization, patients with a germinoma may present with a range of neurological, endocrine and psychiatric symptoms. Pineal region tumors often compress the cerebral aqueduct, resulting in progressive hydrocephalus, and invade the tectal plate, producing a paralysis of upward gaze and convergence known as Parinaud syndrome. Suprasellar germ cell tumors compress the optic chiasm, resulting in visual loss, and present with endocrinopathy due to pituitary failure with diabetes insipidus, retarded growth and sexual maturation (8). Cure rates for this tumor exceed 90% at 10 years, and limitation of treatment-related late morbidity is therefore essential (7).
In this case, the characteristic radiological features of a germinoma were absent (3, 5). There was no mass effect, i.e. compression of pre-existent anatomical structures by growth of a solid tumor, and no enhancement after gadolinium administration. Instead, the tumor was diffusely infiltrating the surrounding tissue and followed the contours of the ventricular system. In addition, the marker placental alkaline phosphatase (PLAP) usually present in germinomas (2) was negative and diagnosis was made on nuclear OCT3/4 staining, which has proven to be a valuable marker in diagnosis of germ cell tumors (6, 1).
Contributed by Jeroen de Jong, MD, Hans Stoop, Martin van den Bent, MD, Johan M. Kros, MD, PhD, Prof. J. Wolter Oosterhuis, MD, PhD, Prof. Leendert H.J. Looijenga, PhD