To the Editor: Magnetic resonance imaging (MRI) is the preferred imaging modality to evaluate pituitary tumors; however a normal MRI scan has to be interpreted with caution. We present a case of pituitary germinoma with a normal MRI at presentation. A 15-y-old boy was evaluated for short stature, polyuria and polydipsia in our clinic. Family history was unremarkable. Patient’s height at 6 y was 105.6 cm (5th percentile), at 13 y 128.75 cm (3rd percentile) and, at 15 y was 133.1 cm (<3rd percentile). Physical exam showed sparse pubic hair and small testes (Tanner stage 2). Laboratory evaluation revealed low IGF-1, normal thyroid function tests, elevated sodium and low urine specific gravity. Bone agewas delayed by 4 y.MRI of the brain and pituitary was normal (Fig. 1a). Patient was diagnosed with diabetes insipidus (DI) and growth failure and started on desmopressin acetate (DDAVP) and growth hormone therapy. The patient’s symptoms resolved and he grew 13 cm. Three years later he presented with fatigue and declining school performance. Physical exam showed small testes (Tanner stage 3). Hormonal evaluation showed a low free T4 and mildly elevated TSH. Thyroid hormone replacement and short duration (3-mo) testosterone therapy were started. Repeat MRI of the brain and pituitary (Fig. 1b) showed pineal gland enlargement, pituitary stalk thickening (PST) and hyperintense lesions in the basal ganglia, internal capsule and corpus callosum. Biopsy revealed pituitary germinoma. Following 6 wk of external beam radiotherapy, repeat MRI showed near complete resolution of lesions. About 32 % of childhood DI cases are idiopathic however growth failure, presentation after age five and anterior pituitary deficiencies suggest an organic etiology of DI [1]. MRI findings in pituitary germinomas include PST, loss of posterior pituitary enhancement, and pituitary gland enlargement; however these are not sensitive or specific [2]. Mootha et al. recommended that patients presenting with apparent idiopathic DI receive pituitary MRIs every 3–6 mo for 1–2 y, then every 6 mo for 5 y to rule out a structural pituitary lesion [3]. Pituitary germinomas can be occult and nonspecific, therefore a comprehensive pituitary evaluation and follow up neuroimaging is essential for an accurate diagnosis.