Endocrine Abstracts

JOINT3442

Introduction: Granular Cell Tumors (GCTs) are exceptionally rare neoplasms arising in the posterior lobe of the pituitary gland (or neurohypophysis). Typically benign and slow growing, these tumors may present with symptoms related to mass effect or hypopituitarism. Due to their nonspecific radiological features, they are often indistinguishable from other sellar lesions, with definitive diagnosis requiring histopathological confirmation. Here, we present a case of GCT with a four-year follow-up, contributing to the limited literature on this entity.

Case Report: A 78-year-old woman presented with insidious visual disturbances. Initial evaluation by ophthalmology revealed a diagnosis of cataracts, but there was no improvement after phacoemulsification surgery. Further assessment revealed bitemporal hemianopsia and cranial MRI identified a 17x15x12mm tumor with suprasellar extension compressing the optic chiasm and contacting with the internal carotid arteries. The lesion exhibited isointensity on T1-weighted imaging and diffuse contrast enhancement. Hormone evaluation revealed hypogonadotropic hypogonadism (FSH 5.1mUI/ml [RR>34], LH 1.2mUI/ml [RR>25]), low TSH (TSH 0.31uUI/ml [RR 0.40-4.00], FT4 1.0ng/dl [RR 0.7-1.5], under levothyroxine treatment), secondary adrenal insufficiency (cortisol 4.2ug/dl [RR 5-25], ACTH<5.0pg/ml [RR 9-52]) and a slight prolactin elevation (45.5ng/ml [RR 5.2-26.5]); IGF1 was normal (161ng/ml [RR 81-225]). Hydrocortisone replacement therapy was initiated. The patient underwent decompressive transsphenoidal surgery, achieving only partial resection of the lesion due to its proximity to critical structures and hypervascularity. Postoperatively, pituitary dysfunction worsened (FSH <1.0mUI/ml, LH <1.0mUI/ml, prolactin 2.4ng/ml, TSH <0.004uUI/ml, FT4 0.70ng/dl, cortisol 1.0ug/dl, ACTH<5.0pg/ml, GH <1.0mg/l, IGF1 39ng/ml). Histopathological examination documented a grade I CGT of the sellar region, with a Ki-67 index of 3%. Immunohistochemistry showed TTF-1 positivity and other pituitary hormone markers were negative. Postoperative imaging revealed a residual sellar and suprasellar lesion measuring 12x13mm, causing obliteration of the suprasellar cistern and inferior molding the optic chiasm. Neuro-ophthalmological assessment confirmed persistence of bitemporal hemianopsia. Four years after surgery, the lesion remains stable, and the patient reports no new symptoms.

Conclusions: GCTs are extremely rare, with just over 100 cases reported in the literature. Consistent with previous reports, this case was associated with hypopituitarism, and surgical excision was challenged by the tumor’s vascularized adherent nature and proximity to critical structures. Despite partial resection, the residual lesion remained stable over four years, highlighting the indolent behavior of these tumors. This report adds valuable insights to the limited knowledge of GCTs and underscores the importance of further studies to guide future clinical practice.