Involvement of Suboccipital Muscles in Plasmacytoma of Occipital Bone

Abstract

Abstract Introduction Suboccipital muscle involvement in a plasmacytoma of occipital bone is a rare clinical event. It leads to a dilemma of categorizing it into either Solitary plasmacytoma or extra medullary plasmacytoma. A working protocol is necessary to follow up these patients to detect their progression into multiple myeloma. Clinical Presentation A 38-year-old man presented with a progressively increasing hard swelling in the occipital region of five years duration. Brain CT revealed an osteolytic SOL over the torcula extending up to the foramen magnum. Brain MRI revealed an extraxial lesion. Brain MRV revealed no involvement of the torcula. Skeletal survey for metastasis was normal. After evaluation, we performed a surgical excision of the lesion. Intraoperatively, the tumor had invaded the suboccipital muscles and parietal bone and was adherent to the dura, without any intracranial extension. Histopathology reported Plasmacytoma. Immunohistochemical analysis was positive for CD-138. Bone marrow biopsy was negative for plasma cells. Bence Jones protein was absent and M protein absent in serum electrophoresis. USG abdomen normal. The patient underwent radiotherapy and is under continuous follow-up. Conclusion Plasmacytoma of occipital bone with suboccipital muscles involvement is categorized as Solitary Plasmacytoma of the bone. This provides convenience in diagnosis, management, and follow-up. We report on this case for its rarity in presentation. The protocol followed in our institute, based on our experience with such tumors, will aid in early identification of the progression of solitary plasmacytoma of bone into multiple myeloma and will augment prompt management.

Keywords

• plasmacytoma
• solitary
• occipital bone
• suboccipital muscle involvement
• progression to multiple myeloma
• follow-up protocol