Pitfalls in diagnosis of the pituitary stalk lesion: infundibulo-neurohypophysitis or germ cell tumor?

Salvatore Raia; Antonella Giampietro; Tommaso Tartaglione; Carmelo Caldarella; Mario Rigante; Marco Gessi; Liverena Lauretti; Pierpaolo Mattogno; Marinis Laura De; Alessandro Olivi; Alfredo Pontecorvi; Francesco Doglietto; Antonio Bianchi; Sabrina Chiloiro

doi:10.1530/endoabs.99.P139

Introduction: Infundibulo-neurohypophysitis (INH) is an uncommon inflammatory disorder. Because of the location of inflammation, it selectively affects the neuropituitary and pituitary stalk. The differential diagnosis remains often challenging with neoplastic lesions, such as germ cell neoplasia, Langerhans cell histiocytosis, Erdheim-Chester Disease, metastasis. Our clinical case is emblematic for pitfalls in diagnosis of the pituitary stalk lesion

Case Report: A 18 years-old male patient was observed at our Center for Pituitary disease in July 2023, for pan-hypopituitarism due to a pituitary stalk lesion. The patient was also affected from Klinefelter syndrome. The patient medical history had started when he was 10 years-old with polyuria/polydipsia. On may 2021, the patient was admitted to another hospital, for asthenia, pubertal delay and persistence of polydipsia/polyuria. Pituitary hormone tests documented pan-hypopituitarism and diabetes insipidus. Hormonal replacement therapy with hydrocortisone, levothyroxine and desmopressin acetate was prescribed. Campimetry evaluation proved a bilateral hemianopsia. A pituitary and brain contrasted MRI proved a sellar and suprasellar lesion, suggestive for a germinoma. Pituitary biopsy was performed, resulting undiagnosed. Therefore, on June 2021, a second pituitary biopsy was conducted, with the detection of inflammatory infiltration of immune cells (B CD20+ and T CD3+), histiocytes and negative immunohistochemistry for c-Kit, PLAP, CD1a, SI 00, MPO, CD30, CD15. The patient was diagnosed for INH. On April 2022, the patient referred to another endocrinology department, where G4 immunoglobulins were dosed resulting normal, antinuclear antibodies were positive, and pituitary MRI showed unchanged the pituitary stalk lesion, and the empty sella due to previous pituitary biopsies. An 18- fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET-CT) showed a suprasellar tracer hyperaccumulation (SUV 23.2). Patient was treated with high dose corticosteroid therapy without a clinical and neuroradiology improvement. On October 2022, a pituitary MRI showed a reduction in size of the tissue sited in the suprasellar space, in absence of resolution of the campimetry deficit. The patient was referred to our Pituitary centre for an additional neurosurgical evaluation, for considering a third neurosurgical debulking. An endocrine evaluation confirmed the pan-hypopituitarism, the pituitary MRI showed unchanged the pituitary stalk lesion but a neuroradiological evaluation together with 18F-Fluorocholine PET-CT was suggestive for a germ cell tumor, then confirmed by histology.

Conclusion: Our case confirms the difficult in the differential diagnosis of pituitary stalk lesions, underlining the need of a multidisciplinary approach, through the application of clinical, molecular, pathology and imaging techniques, also considering the emerging role of functional imaging.

Endocrine Abstracts

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