A Rare Case of Primary Pituitary Diffuse Large B-Cell Lymphoma

Primary pituitary lymphoma represents a very rare malignant condition, with as few as 40 cases reported in the largest series published to date. We present the case of a 66-year-old patient diagnosed with primary pituitary DLBCL. The patient first presented in August 2023 with frontal headache and right-side palpebral ptosis. Cerebral imaging studies revealed a sellar and suprasellar mass with sinusal extension, measuring 15 mm in diameter. A surgical excision was performed, with the initial histopathological report indicating a pituitary adenoma with areas of pituitary apoplexy. Given the lack of clinical improvement and the persistence of the tumour on repeated cerebral imaging, a second interpretation of the histological slides was solicited, which determined the diagnosis of DLBCL. A whole-body CT scan found no other localisation of the disease, supporting the diagnosis of primary pituitary lymphoma. The patient received R-CHOP immunochemotherapy with clinical improvement of his symptoms, followed by the apparition of secondary cerebral lesions shortly after treatment completion. Primary pituitary lymphoma is a rare form of malignancy which predisposes to diagnostic errors. Accurate diagnosis requires the integration of imaging and histopathological data within the clinical context, while the treatment strategy needs to address the unique challenges raised by this particular tumour localisation.