A pineal region germ cell tumor with rapid enlargement after a long-term follow-up: case report

The natural history of pineal region germ cell tumors (GCTs) is not well known. We report a rare case of a pineal region GCT showing rapid enlargement within 2 months, after 7 years with no growth.

A boy presented with gonadotropin-independent precocious puberty at 6 years 10 months of age. Although a slight elevation of β-human chorionic gonadotropin suggested that a small pineal cystic lesion observed on magnetic resonance imaging might be an β-human chorionic gonadotropin--producing tumor, it was not clear whether the mass was truly a GCT. Accordingly, we followed up the pineal lesion and serum pituitary gonadotropin levels for approximately 7 years. After this period without essential tumor growth, the pineal tumor suddenly showed rapid enlargement, which prompted treatment. A histopathological investigation revealed a mixed GCT with a germinoma and an immature teratoma. Serum pituitary gonadotropin levels at 5 years after the first examination had increased to normal pubertal ranges. Although the pituitary gonadotropin levels had remained low during the period with no tumor growth, the gonadotropin levels were elevated and had continued to increase at least 2 years before the rapid enlargement of the tumor.

These phenomena suggest that levels of neuroendocrinological parameters such as pituitary gonadotropin at puberty might affect the enlargement of pineal region GCTs, which might account for the natural history of GCTs, ie, their frequent detection at puberty.