A 77-year-old Japanese man presented to the author's department with diarrhea and weight loss (8 kg in the past 3 months). Vital signs were normal. Furthermore, abdominal examination was normal, and no skin lesions were observed. Esophagogastroduodenoscopy and total colonoscopy confirmed the absence of malignancy and inflammation; however, contrast-enhanced computed tomography revealed left inguinal lymphadenopathy. Laboratory evaluation showed white blood cell counts and serum lactate dehydrogenase (LDH) level were elevated at 16,500 /μL (range ≤8,500) and 272 IU/L (range ≤229), respectively.