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Background:Solitary plasmocytoma is a rare tumour that represents around 2 to 5% of all plasma cell dyscrasias. It normally affects soft tissu but rarely the bone. Diagnosis is based on histology, the absence of bone marrow involvement.Objectives:To drag attention to think of solitary plasmocytoma of bone when dealing with a vertebral fracture in the absence of the CRAB criteria of multiple myeloma.Methods:We report a rare case of a vertebral fracture of the 4th lumbar vertebra (L4) revealing a solitary plasmocytoma of bone.Results:A 67-year-old female patient presented to our rheumatology department with back and left radicular pain of brutal onset, 15 days prior to her visit. Pain was severe and awakened her at nights. On examination, mobilities of the spine were unchanged but on palpation she had exquisite pain of L4. Laboratory tests showed a normal sedimentation rate of 15mm the first hour, a negative c-reactive protein, normal calcemia and kidney tests. X-rays of lumbar spine showed a vertebral fracture with a destruction over 50% of the vertebral size and cortical rupture. MRI of the spine showed the absence of other lytic lesions or other fractures or spinal cord compression and showed the total destruction oft he anterior vertebral body of L4 (Figure 1). Protein electrophoresis was in normal range and 24h urinary proteinuria was negative. Other tests rules out gynecological, thyroid, and renal neoplasms. Sternal puncture showed a rich bone marrow of normal cells without further infiltration. Bone biopsy of the detected lesion showed tumour cells made of mature plasmocytes confirming the diagnosis of solitary plasmocytoma of the bone. The patient was treated with radiation therapy. The evolution after 24 months showed a stabalised lesion and the absence of progression to multiple myeloma.Figure 1.T2 weighted MRI showing the vertebral fracture of L4Conclusion:It is important to keep in mind the diagnosis of solitary plasmocytoma of bone when facing a solitary lesion or vertebral fracture despite relatively non agressive radiological signs. It is also important to note the possible evolution to multiple myeloma and keep a hawk-eyed guard.References:[1]Masmoudi K, Elleuch E, Akrout R, et al. Le plasmocytome solitaire osseux: à propos de 3 cas et revue de la littérature. Pan Afr Med J; 25. Epub ahead of print 6 December 2016. DOI: 10.11604/pamj.2016.25.219.10933.Disclosure of Interests:None declared