Intravascular malignant lymphomatosis (IML) is characterized by proliferation of malignant lymphoid B cells within the lumens of small vessels. Common symptoms include general weakness and central neurological and cutaneous signs. Only histopathological analysis can confirm the diagnosis. We report on a 69-year-old man hospitalized for general weakness, inflammatory syndrome, and hemophagocytic syndrome (HS). Our observation shows that histopathological signs may be observed on a muscular biopsy without clinical or biological signs of muscular involvement.