Hypercalcaemia as the first clinical manifestation of follicular lymphoma

Hypercalcaemia is a common biochemical complication of malignancy, affecting 20%-30% of patients with cancer. Hypercalcaemia of malignancy (HCM) can be driven by multiple different pathological mechanisms, each with variable associations and frequencies across different malignancy types.HCM in indolent lymphomas is exceptionally rare, with only isolated case reports citing its occurrence, and it rarely emerges as the first clinical manifestation. In the case report, we describe a patient with low-grade follicular lymphoma who presented acutely with HCM. This case underscores the importance of identifying the specific mechanism driving HCM to guide timely, targeted treatment and reminds clinicians that, although uncommon, hypercalcaemia can be the initial manifestation of a low-grade lymphoma.