Germinomas are highly immunogenic
tumors eliciting a strong peri-tumoral immune response that can spillover into the surrounding healthy tissues. This phenomenon can also occur in intracranial
germinomas, manifesting as secondary
hypophysitis. Herein, we report a case of 12-year-old-girl presenting with
polyuria and polydispsia. She had
central diabetes insipidus (CDI) and
panhypopituitarism. Imaging revealed a sellar-suprasellar mass with infundibular stalk thickening. Transphenoidal biopsy revealed epithelioid
granulomas with immunostaining negative for germinomatous cells. Other causes of
hypophysitis were ruled out. Accordingly, she was diagnosed as primary granulomatous
hypophysitis and treated with high-dose
corticosteroids. Three years later she again presented with
headache,
vomiting and diminution of vision. Imaging showed a heterogeneous, solid-cystic peripheral rim-enhancing lesion at the same location with involvement of hypothalamus, ependyma and pineal gland. Cerebrospinal fluid beta-
human chorionic gonadotropin was markedly elevated, confirming the diagnosis of an intracranial
germ cell tumor. She was started on
chemotherapy; however, she succumbed to
febrile neutropenia. We performed a literature search and found 18 anecdotal cases of secondary
hypophysitis associated with intracranial
germinomas. There was a slight male preponderance (male:female 5:4). Two-thirds of the cases were below 18 years of age.
Polyuria was the most common presenting manifestation (83%). CDI and
panhypopituitarism were seen in 89 and 78% cases, respectively. Imaging evidence of pituitary stalk thickening was seen in 12 cases (67%), while pituitary enlargement and/or sellar mass were reported in 11 cases (61%). Pineal involvement was extremely rare, being reported in only 1 case, implying the predilection of suprasellar (rather than pineal)
germinomas in causing secondary
hypophysitis. Histologically, 82% had
lymphocytic hypophysitis, while 18% had granulomatous
hypophysitis. Initially, the diagnosis of
germinoma was missed in 60% of the cases who were wrongly treated with
corticosteroids. To conclude, physicians should make it a dictum that all children and adolescents presenting with CDI and pituitary stalk thickening should be rigorously screened for an underlying intracranial
germinoma before labeling them as primary
hypophysitis.