464 Local Extension of a Solitary Extra Medullary Nasal Plasmacytoma into the Orbit

Abstract Aim Extramedullary plasmacytoma are rare neoplasms, which mainly occur in the head and neck, the most common site being the nasal cavity or septum. Patients may present with epistaxis, nasal obstruction, or rhinorrhoea. Extension into the orbit is rare but can lead to visual disturbances. Method This case report pertains to a 69-year-old female patient who initially presented with a 6-week history of recurrent sinusitis, with left sided cheek pain and diplopia. Results A CT and MRI scan was performed, which showed opacification of the left maxillary, ethmoid and sphenoid sinuses with bony destruction of the medial and anterior maxillary walls and into the anterior soft tissues. The mass was completely obstructing the left nasal cavity extending into the inferomedial orbit. Staging CT scans also showed nodal disease in the neck. Biopsy with histology was positive for CD138, with diffuse proliferation of plasma cells of varying maturity and atypia. Additionally, mono IgG kappa was also positive as was CD45 suggestive of a lymphoid neoplasm. Bone marrow biopsy and PET scan confirmed there was no systemic involvement. Radiotherapy was initiated after the patient recovered from COVID -19. A repeat MRI scan 6 weeks post radiotherapy showed a partial response with reduction in the size of the tumour, resolution of the intra-orbital extension and disappearance of paraprotein. Conclusions This case report illustrates need for earlier consideration of EMP diagnostically to reduce the risk of conversion of the plasmacytoma to multiple myeloma, which is a known possibility and to ensure minimal delay in the commencement of treatment.