Splenic rupture (SR) is a rare adverse event observed in patients treated with G-CSF as a peripheral hematopoietic stem cell (PHSC) mobilizing agent, mostly in myeloma multiple and amiloidosis; to date, to our knowledge, it has not been previously described in plasma-cell leukemia (PCL). We report a case of a woman with PCL, who presented a SR after PHSC mobilization with Cyclophosphamide+G-CSF. The spleen removed showed hematopoietic foci and amiloid material. In the course of a second mobilization, 2 months after, the patient died from sepsis. We considered it important to report this case, in order to keep in mind the possibility of SR in patients with malignant gammopathy.