{"doi":"10.1210/jcemcr/luaf031","title":"Treatment of Extraosseous Giant Cell Tumor of Bone and Calcitriol-Mediated Hypercalcemia With Denosumab in Paget Disease","abstract":"Abstract Extraosseous giant cell tumor of bone (GCTB) associated with Paget disease of bone (PDB) is rare. We report a patient aged in their 70s with polyostotic PDB involving the skull, spine, and pelvis, previously treated with bisphosphonates, who presented with symptomatic hypercalcemia (calcium 14.8 mg/dL [3.7 mmol/L]; reference range [RR], 8.6-10.5 mg/dL [2.1-2.6 mmol/L]), kidney injury (creatinine 2.6 mg/dL [230 μmol/L]; RR, 0.4-1.1 mg/dL [35-97 μmol/L]), and a 17.5 cm pelvic mass. Testing showed elevated calcitriol or 1,25-dihydroxyvitamin D (1,25(OH)2D) (57-108 pg/mL [137-259 pmol/L]; RR, 18-72 pg/mL [43-173 pmol/L]), but normal parathyroid hormone and bone-specific alkaline phosphatase (BSAP), arguing against parathyroid autonomy and active osseous PDB. Histopathology showed osteoclast-like giant cells and stromal mononuclear cells without atypia, necrosis, or mitoses. A one-time dose of denosumab 120 mg resulted in normalized calcium (9.0 mg/dL [2.2 mmol/L]) and 1,25(OH)2D (24 pg/mL [57 pmol/L]) and reduced tumor size. Denosumab was continued at a dose of 60 mg every 6 months. After 20 months, calcium and 1,25(OH)2D remained normal, with no tumor regrowth, and BSAP stayed low. This is the first report of 1,25(OH)2D-mediated hypercalcemia in extraosseous GCTB. It responded well to denosumab. Long-term management options are discussed in the context of existing literature.","journal":"JCEM Case Reports","year":2025,"id":550326,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9535,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":470170,"name":"Clemens Bergwitz","orcid":"0000-0002-7518-249X","position":1,"is_corresponding":false},{"id":1445597,"name":"Oyunbileg Magvanjav","orcid":"0000-0002-2426-9157","position":0,"is_corresponding":true}],"reference_count":31,"raw_metadata":null,"created_at":"2026-07-19T02:54:16.596730Z","pmid":"40110572","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}