前列腺癌被广泛认为是中年和老年男性高发的一种癌症，并且骨转移是其主要的转移部位。然而，50岁以下的患者很少患前列腺癌，颈部肿胀也很少是其最初的症状。在此我们报告了一例初步诊断为来源不明的多发淋巴结和骨转移的47岁日本男性患者，最终确诊为差异化差的前列腺癌。该患者已开始进行内分泌治疗，目前未见进展。在研究来源不明的男性患者时，需要考虑到前列腺癌的可能性，确认血清前列腺特异抗原水平，并进行局部前列腺评估。© 2023. BioMed Central Ltd., part of Springer Nature.

Prostate cancer has been well known to have a high prevalence among middle-aged and older men, with high incidence of metastases to the bone-the main metastatic site. However, prostate cancer among those less than 50 years of age is extremely rare, and neck swelling is seldom the initial symptom.We herein report case of a 47-year-old Japanese male with poorly differentiated prostate cancer that had been initially diagnosed as a cancer of unknown primary with multiple lymph node and bone metastases before reaching a definitive diagnosis. The patient has been started on endocrine therapy and is currently alive without progression.When locating the primary lesion in men with cancer of unknown primary, it is important to consider the possibility of prostate cancer, confirm serum prostate-specific antigen levels, and perform local prostate evaluation.© 2023. BioMed Central Ltd., part of Springer Nature.