Malignancy-associated Hypercalcemia as the Initial Manifestation of Pulmonary Mucosa Associated Lymphoid Tissue Lymphoma

Abstract

Aims: Hypercalcemia is a frequent metdabolic disturbance in oncology, yet exceedingly rare in indolent lymphomas such as pulmonary mucosa-associated lymphoid tissue (MALT) or bronchus-associated lymphoid tissue (BALT) lymphoma. We aim to present a rare case of pulmonary BALT lymphoma initially manifesting with severe hypercalcemia successfully treated with denosumab in the context of renal dysfunction. Presentation of Case: A 75-year-old woman with a pulmonary lesion followed conservatively for 10 years was admitted with fatigue and poor oral intake. Laboratory evaluation revealed calcium 15 mg/dL and acute kidney injury. Imaging demonstrated a 9 × 9 cm centrally located pulmonary mass with high FDG uptake. Histopathology confirmed BALT lymphoma. Bisphosphonates were contraindicated due to impaired renal function, and denosumab (60 mg, subcutaneously) was administered, achieving rapid normalization of serum calcium. The patient was subsequently treated with rituximab–bendamustine. Discussion: Pulmonary MALT/BALT lymphomas usually follow an indolent course, often warranting a “watch-and-wait” strategy. However, this case highlights that life-threatening metabolic complications may occur. Hypercalcemia is well described in aggressive B-cell lymphomas but is exceedingly rare in marginal zone lymphomas. Denosumab is a guideline-endorsed option for hypercalcemia of malignancy, particularly in patients with renal impairment. Conclusion: This case emphasizes the need for vigilance regarding metabolic complications in indolent pulmonary lymphomas. Denosumab offers an effective alternative when bisphosphonates are contraindicated, and systemic therapy should be initiated upon development of significant complications.