Extraosseous Plasmacytoma of the Parotid Gland: a Case Report and Literature Review

Objectives: Myeloma is a neoplasm of plasma cells that causes painful, bone-destructive lesions. It may present as a solitary lesion (plasmacytoma), or involve multiple sites (multiple myeloma). Extraosseous plasmacytoma is an uncommon malignant tumor that is characterised by the monoclonal proliferation of abnormal plasma cells in soft tissue. Although the majority of extraosseous plasmacytoma lesions occur in the head and neck, plasmacytoma of the parotid gland is extremely uncommon.

Methods: In this paper, we describe a very rare case of a male with parotid gland plasmacytoma which extended into the parapharyngeal space and to the condylar process of mandible.

Results: The biopsy was performed and the specimen was submitted for histopathological examination. An immunohistichemical study revealed monotypic κ light chain restriction. Therefore, a diagnosis of κ plasmacytic plasmacytoma was determined. To differentiate between plasmacytoma and myeloma, a systemic workup was performed. The patient was referred to the Oncology Department for further treatment.

Conclusion: A plasmacytoma is a solitary mass of neoplastic mono¬clonal plasma cells, which can arise in any area of the body. Soft tissue plasmacytomas of the head and neck tend to involve the nasal cavity or nasopharynx, rather than the oral cavity. Although patients with parotid enlargements are commonly observed in everyday clinical practice, extraosseous plasmacytoma arising in the parotid gland is extremely rare. Fine needle aspiration cytology, histopathological examination, immu¬nohistochemical analysis aid in providing an accurate diagnosis and treatment. Extraosseous plasmacytoma should be considered in the differential diagnosis of parotid tumors.