Solitary plasmacytoma of bone with oncogenic osteomalacia: recurrence of tumour confirmed by PET/CT. A case report with a review of the radiological literature

We describe a case of oncogenic osteomalacia secondary to solitary plasmacytoma of the vertebral body of T3. The patient presented with symptoms of hypophosphataemia. Following the initial diagnosis, the lesion was surgically resected with good results, although several follow-up procedures, including bone grafting, were necessary to stabilize the thoracic spine. The lesion recurred almost 15 years after its initial resection, again presenting with hypophosphataemia and neurological symptoms suggestive of local tumour recurrence. A variety of radiological examinations were performed in an attempt to confirm and localize recurrent tumour, including bone scintigraphy, (111)indium octreotide scintigraphy, high-resolution CT and MRI of the thoracic spine, but these yielded only negative or equivocal results owing, in part, to the presence of extensive post-operative changes, and also to a difference in the MR signals of the recurrent and original tumours. Positron emission tomography (PET/CT) demonstrated a solitary focus of intense fluorodeoxyglucose uptake in the T3 vertebral body, enabling a definitive diagnosis of recurrent plasmacytoma. This case illustrates the diagnostic value of PET/CT in the setting of challenging post-operative changes in the surrounding tissue and in the appearance of the tumour itself. Relevant related imaging literature is also reviewed.