Endocrine Abstracts

Introduction: Pituitary adenomas, more recently referred to as pituitary neuroendocrine tumors (PitNets) from other organs, are common neoplasms comprising 10 to 20% on intracranial tumors. Null cell adenoma is a diagnosis of exclusion that requires immunonegativity for all adenohypophyseal hormones and a lack of cell type-specific transcription factors. It represents 0,6% of all pituitary tumors.

Case: A 55 years old women with a history of treated thyroid vesicular carcinoma in remission currently. Followed for a geant agressif adenoma discovered following a headaches and a progressive decline in visual acuity associated with visual impairment (diplopia). The MRI (magnetic resonance imaging) of the sellar region had shown a voluminous endosellar process measuring 55x44x32mm, partially encysted with haemorrhagic changes, compressing the optic chiasm and invading the left cavernous sinus (KNOSP03). Hormonal workup revealed a serum prolactin level of 192ng/ml and gonadotropic deficiency. The ophthalmic examination found bitemporal hemianopia. The patient was then started on dopamine agonist (cabergoline) with a gradual increase in doses up to 3,5mg/week for two months. Then the patient only consulted a year later while having kept the same therapy. The MRI reveals a slight increase in the side of the process becoming KNOSP4. She had a transphenoidal adenemectomy. The histological analysis confirmed after three attempts a null cell adenoma (IHC for pituitary hormones and transcriptor factors). Four months later, the ophthalmic examination shown a stability and the MRI of the sellar region had shown the persistence of a voluminous tumor remnant discreetly lateralized on the left almost completely filling the optochiasmatic cistern, measuring 24x19 mm in the transverse axes, extended over a height of 32 mm, hyposignal in T1 and hypersignal in T2 wiehgted image, heterogeneous, enhanced discreetly and peripherally after injection of gadolinium salts.

Conclusion: Null cell adenoma represents a challenging diagnostic group of tumors. Close collaboration of the “pituitary team” is essential for a precise diagnosis and will contribute to the optimal treatment of the patient. New classifications, novel prognostics markers, and emerging imaging and therapeutic approaches will need to be evaluated to better serve this unique group of patients.