Solitary plasmocytoma is a rare tumour that belongs to the myeloid dysplasia group. The authors present an unusual evolution of this pathology through a clinical case. A 42-year-old patient was diagnosed with solitary nasosinusal plasmocytoma following biopsy of the right nasal fossa process; several weeks after this the tumour spontaneously regressed. Extramedullar plasmocytoma is a myeloid dysplasia that seldom evolves into multiple myeloma. Spontaneous regression has been described for some malignancies, implying immunological factors, but not previously for extramedullary plasmocytoma.
Solitary plasmocytoma is a rare malignant tumour, characterized by neoplastic proliferation of differentiated B-cells. Two entities have been reported: solitary plasmocytoma of bone (90%) and extramedullary plasmocytoma (10%) preferentially reaching the submucosa of the upper airway, such as the nasal cavity or posterior oropharynx.
The authors report an original case of nasosinusal solitary plasmocytoma, which regressed spontaneously after incisional biopsy. They are not aware of any other reports of spontaneous regression of extramedullary plasmocytoma.
A 42-year-old man, presented to the authors’ department with a 2-month history of headache and permanent right nasal obstruction without epistaxis or rhinorrhoea. On examination, the right nasal airflow was absent. Nasal endoscopy showed a budding tumour of the right nasal cavity. Initial biopsy revealed a light chain plasmocytoma. A CT scan of the head showed a mass on the right maxillary sinus and right nasal cavity ( Fig. 1 ). A systemic workup to assess dissemination of tumour cells was normal; it included bone marrow aspiration, skeletal radiography, abdominal ultrasound, complete blood count, serum biochemistry, and monoclonal immunoglobulin levels of serum and urine. A diagnosis of solitary extramedullary plasmocytoma was confirmed. The patient was listed for a surgical treatment and radiotherapy, but just before it was due to start the authors could find no sign of active disease. An endoscopy control 4 weeks later revealed a sub-normal mucosa and no mass in the right nasal cavity or sinus. No treatment was administrated to the patient during that period. A CT scan control showed total regression of the tumour ( Fig. 2 ).
The diagnosis of plasmocytoma was reconfirmed with several histopathological findings including proliferation of plasma cells, positive immunoreactivity for CD38, and expression of the lambda restricted light chain ( Figs 3 and 4 ). The patient is seen at regular follow ups. One year after diagnosis, the patient had no evidence of disease.