Endocrine Abstracts

Introduction: Cushing’s Disease results of corticotrophin (ACTH) hypersecretion from pituitary which increases cortisol production. WHO classified pituitary tumors as typical adenoma, atypical adenoma and carcinoma. Diagnostic criteria for an atypical adenoma include invasive growth, elevated mitotic index, Ki-67 labeling index greater than 3% and extensive p53 immunoreactivity.

Case Report: Sixty-eight years-old man presented to our consult with history of visual complaints, brain MRI showing a 15 mm invasive pituitary macroadenoma and with hormonal testing revealing ACTH 100 pg/ml (9–52), urinary free cortisol (UFC) 591 μg/24 h (10–136) and hypogonadotropic hypogonadism. He repeated UFC that was positive and made a low dose dexamethasone test (LDDST) with no suppression. The results of the high dose dexamethasone test and the CRH test were not suggestive of CD. Inferior petrosal sinus sampling for ACTH was performed only on the right side with no central/peripheral gradient. Neck, chest and abdomen CT showed no significant alterations. He was submitted to transsphenoidal resection due invasive macroadenoma with compressive symptoms, including left ptosis worsening. Tumor pathology showed epithelial neoplasia type with atypia and frequent mitoses. There was diffuse ACTH staining and almost diffuse p53 expression. Ki67 labelling index was 25%. After surgery ACTH 73.6 (<63.3 pg/ml) and LDDST suppression. The patient began treatment with ketoconazole and was proposed for radiotherapy.

Conclusions: Dynamic noninvasive tests were not suggestive of CD, however these tests have poor negative predictive value. Carcinoma is defined by the presence of metastases, who this patient did not reveal. This clinic case illustrates an example of a pituitary tumor with a pathological and immunohistochemical studies indicating a highly proliferative activity, aggressive growth and malignant potential, even so it is classified as atypical tumor. These tumors must have a tight follow-up for early detection of recurrence and/or metastasis.