Dumbbell-shaped primary CNS lymphoma involving the hypothalamus and pituitary gland

Background: Primary central nervous system lymphoma (PCNSL) involving the hypothalamus and pituitary gland is extremely rare. Therefore, no case to our knowledge has been reported to date. Objective: We described our findings in a 48-year-old immunocompetent man, who presented with four months progressive diabetes insipidus (DI) and two months subsequent headache. Methods and Results: A radiological study and magnetic resonance imaging (MM) suggested a homogeneous enhancing dumbbell-shaped lesion, 2.4 x 1.2 cm in size, involving both the hypothalamus and pituitary gland. A brain biopsy was conducted through a transnasal transsphenoidal approach, and a final histopathological diagnosis of the tumor was confirmed as diffuse large B-cell malignant lymphoma. After extensive tumor surveys, including computed tomography, MRI, ultrasound, bone marrow biopsy, lumbar puncture, and positron emission tomography (PET), no evidence of other lesions found. Subsequently, he received six cycles of intravenous high-dose methotrexate-based chemotherapy followed by one cycle of whole-brain radiotherapy. The progressive DI and headache completely resolved and he was in good health 11 months later. Conclusion: Clinicians should consider the possibility of PCNSL in non specific clinical presentations.