Primary pituitary lymphoma successfully treated with Bruton’s tyrosine kinase inhibitor monotherapy: case report

Introduction: Primary pituitary lymphoma (PPL) is a rare disease characterized by lymphoma confined to the sella or parasellar region without systemic involvement. The clinical symptoms of PPL may include headache, hypopituitarism, visual field disturbance and visual impairment. To date, there is no established standard treatment for this condition. Here, we present a case of successful treatment with a Bruton’s tyrosine kinase (BTK) inhibitor. Case report: A 78-years-old man with a history of severe left renal insufficiency caused by retroperitoneal fibrosis, and sequential right nephrostomy, underwent brain magnetic resonance imaging (MRI) due to the altered hormonal status. An enlarged pituitary stalk was noted and led to a diagnosis of lymphocytic hypopituitarism. Six months later, visual field disturbance and visual acuity deterioration developed, and an MRI revealed a neoplastic lesion and further enlargement of the stalk and the pituitary itself, with an obvious optic nerve compression. Expedited transsphenoidal partial resection was performed to relieve the compression. Pathohystology led to the diagnosis of the large B-cell lymphoma of the germinal center origin. Because of the patient’s poor renal function, high-dose methotrexate therapy was not an option; rather, the patient was treated with a BTK inhibitor - tirabrutinib. Symptoms improved within a week, and a follow-up MRI confirmed a marked reduction of the pituitary lesion. Conclusion: BTK inhibitors may be considered as a first-line treatment option for PPL, especially in patients with contraindications for other treatment protocols.