Abstract: Lynch syndrome is an autosomal dominant hereditary cancer syndrome characterized by germline mutations in DNA mismatch repair genes. Lynch syndrome-associated small cell neuroendocrine carcinoma of the prostate is an extremely rare extracolonic tumor associated with Lynch syndrome. This article reports the case of a 54-year-old male with Lynch syndrome who developed a prostate tumor pathologically confirmed as small cell neuroendocrine carcinoma of the prostate, accompanied by a loss of MSH1 and PSM2 protein expression. This article reviews the clinical features and imaging findings of this disease to enhance clinical awareness and provide insights for early diagnosis of this condition.