Beyond Heart Failure: Unmasking Metastatic Prostate Adenocarcinoma Through Marked Alkaline Phosphatase Elevation

An 85-year-old man presented with progressive dyspnea and chest tightness after several months of worsening lower back pain.Initial evaluation showed hypoxemia, peripheral edema, an elevated pro-B-type natriuretic peptide level, cardiomegaly, and small bilateral pleural effusions; CT pulmonary angiography showed no pulmonary embolism.He was treated for presumed acute heart failure, but his dyspnea improved only mildly over the first hospital days.Further evaluation demonstrated a markedly elevated alkaline phosphatase (ALP) level of 2,152 U/L and a prostate-specific antigen level reported as 725 ng/mL.The CT showed diffuse skeletal sclerosis, and PET imaging demonstrated extensive osseous lesions with pelvic and retroperitoneal lymphadenopathy.The CT-guided biopsy of a left iliac bone lesion showed adenocarcinoma consistent with a prostatic primary.This case highlights the importance of reassessing an initial working diagnosis when the clinical course is incompletely explained and considering an underlying malignancy when progressive skeletal pain, marked ALP elevation, and sclerotic bone lesions occur together.