ESPE Abstracts

Background: Patients who present with clinical and laboratory findings of pituitary dysfunction and whose MRI findings reveal increased pituitary size or thickening of pituitary stalk, pose a diagnostic challenge. The differential diagnosis mainly includes dysgerminoma, histiocytosis, and hypophysitis. A non-invasive approach is often non-diagnostic.

Objective and hypotheses: To present two patients with similar clinical picture and positive MRI findings, in whom transphenoidal biopsy of the pituitary lesion, led to prompt accurate diagnosis and further therapeutic management.

Method: Patient 1: Prepubertal girl 8 years of age, presented with the main complaint of slow growth rate. Detailed history revealed polydipsia and polyuria. Growth curve evaluation revealed a change of percentile from the 50th to the 15th percentile in the previous 3 years. Physical exam was unremarkable and she was prepubertal. MRI of the hypothalamo-pituitary region revealed enlargement of the anterior pituitary lobe and thickening of the pituitary stalk, enhancing with gadolenium. Displacement of the optic chiasma was appreciated. Skeletal survey, chest X-ray and abdominal US were normal, HCG blood and CSF levels were low as well as CSF cell count/protein. A transphenoidal biopsy of the lesion revealed dysgerminoma. Patient 2: Adolescent girl 15.5 years old, presented with a history of diabetes insipidus, of 2 years duration, and irregular menses. Physical exam was unremarkable and she was fully pubertal. MRI revealed thickening of the pituitary stalk 3.8 mm. Follow-up MRI revealed further enlargement up to 5.4 mm. Skeletal survey, chest X-ray, and abdominal US were normal, HCG blood and CSF levels were low as well as CSF cell count. Transphenoidal biopsy revealed dysgerminoma.

Conclusions: Ttissue biopsy provides the definitive diagnosis and the transphenoidal approach appears to be optimal for certain patients. Inconclusive imaging appearance, negative markers, and slow progression cannot exclude the diagnosis of germinoma.