The pituitary gland represents an uncommon site for malignant tumors and metastatic lesions. Among metastatic tumors, breast and lung cancers account for more than 50% of cases, with colon carcinoma contributing to 2%–3%. The presence of pituitary metastases significantly impacts the prognosis, and poses a risk to the patient well-being, through the induction of hypopituitarism, notably in the context of secondary adrenal insufficiency. It is noteworthy that diabetes insipidus is a predominant clinical manifestation reflecting frequent posterior lobe affection.1-3

A 68-year-old woman was admitted to a hospital following a sudden right-eye visual impairment. Her medical history included descending colon adenocarcinoma, which had been complicated by intestinal perforation and fecal peritonitis 7 months prior to the admission. This condition necessitated left hemicolectomy, with transverse colostomy and adjuvant chemotherapy treatment due to peritoneal and hepatic metastases. Upon admission, the patient reported weakness and nocturnal enuresis over the past 3 months. Physical examination revealed unilateral and painless vision loss, with the absence of other neurologic symptoms. After an ophthalmologic consultation, the patient underwent a magnetic resonance (MR) examination of the head. The MR scans revealed a polycyclic mass within the anterior cranial fossa, penetrating the sella turcica on the right side, extending into the right cavernous sinus, infiltrating the optic chiasm, and displacing the pituitary infundibulum (Figure 1A–1F). A suspicion of a metastatic lesion was raised because the morphologic characteristics of the tumor on the MR images were atypical for the most common pathologies. Laboratory investigations showed partial hormonal dysfunction of the pituitary gland, encompassing insufficiency in the gonadotropic and thyrotropic axis, alongside hyperprolactinemia. Dysfunction in the adrenocorticotropic axis could not be ruled out due to dexamethasone treatment, which was employed to mitigate edema and alleviate optic nerve compression. Due to the urgency of the case, a full diagnostic process to confirm diabetes insipidus (water deprivation test, desmopressin test) was abandoned after an endocrinologic consultation. Polyuria, low urine density, high serum osmolality, good response to desmopressin, and exclusion of other causes of nycturia confirmed the diagnosis of this disorder (Supplementary material, Table S1). Consequently, treatment with levothyroxine and desmopressin was initiated. Subsequently, the patient was qualified for transcranial tumor resection, employing the fronto-sphenoidal approach. Postoperative histologic examination identified adenocarcinoma metastasis as the cause of the patient’s symptoms. Although a follow-up MR examination confirmed decompression of the optic chiasm, the patient experienced binocular vision loss. It can be inferred that the vision loss and pituitary insufficiency were most likely secondary to the metastatic lesion, and were associated with the mass effect. The patient was referred for ongoing oncologic treatment and remains under the joint care of the ophthalmology and endocrinology outpatient clinics.

Figure 1. Two pathologic masses visible on T1-weighted fat-saturated contrast-enhanced axial (A) and T2-weighted fluid-attenuated inversion recovery images (B). Polycyclic tumor (asterisk) of the sella turcica consistent with a metastasis from the colon carcinoma invades the suprasellar region, together with the optic chiasm. The growth pattern and T2 signal are indicative of neither meningioma nor primary pituitary lesion. Another focal lesion (arrow) surrounded by edema (B) is visible in the right temporo-occipital region; the lesion presents dural tail sign and homogenous, vivid contrast enhancement, which may indicate meningioma; however, the differential diagnosis should include meningeal metastasis. Sagittal T1-weighted contrast-enhanced (C) and T2-weighted (D) high-resolution images showing suprasellar expansion of the pituitary lesion, reaching the level of the optic chiasm. On the coronal sections of T1-weighted contrast-enhanced (E) and 3-dimensional T2-weighted (F) images, encapsulation of the infundibulum is well visible; bilaterally adjacent to the cavernous sinus and the internal carotid arteries (arrows). Small T2 hyperintensity (F, arrow) in the right part of the mass is consistent with a cystic component (exhibiting low T1 signal as well; E, asterisk).

Screening tests, advanced diagnostic modalities, and enhanced therapeutic interventions have contributed to improved prognosis and prolonged survival rates among oncologic patients. Consequently, late neoplastic recurrences, after extended periods of remission, may affect uncommon organs, such as the pituitary gland. This underscores the importance of considering the pituitary gland as a potential site for metastasis, and highlights the need for clinical vigilance. Furthermore, the sudden onset of hypopituitarism in elderly individuals warrants inclusion of metastatic tumors in the differential diagnosis, particularly when the patients have a documented history of cancer.4,5