Neurohypophyseal germinoma with abundant fibrous tissue.

We report an unusual case of neurohypophyseal germinoma with abundant fibrous tissue and clival invasion that was initially misdiagnosed as lymphocytic hypophysitis. A 40-year-old woman presented with diabetes insipidus and panhypopituitarism after delivering her second son and which lasted for 4 years. Magnetic resonance imaging showed the intrasellar mass extending to the suprasellar region with enlarged pituitary stalk. The mass was heterogeneously enhanced and invaded the clivus. Biopsy of the intrasellar mass was performed via the trans-sphenoidal route, and histological examination revealed marked fibrous tissue and infiltration of lymphocytes, with no evidence of tumor cells. Lymphocytic hypophysitis was the initial diagnosis, and corticosteroid therapy was begun. Despite intensive treatment, the lesion enlarged and clinical symptoms worsened 2 weeks after surgery. Subtotal removal of the mass was performed, and a second histological examination revealed typical findings of the germinoma. Subsequently, the patient underwent chemoradiotherapy, and complete remission was achieved. Histological diagnosis is sometimes incorrect in fibrous tumors at the sellar region, and biopsy from several points is strongly recommended for this entity.