Clinical progression of multiple myeloma presenting as parotid gland plasmacytoma

Abstract

Plasmacytomas are tumors of plasma cells which can be divided into medullary or extramedullary type depending on the site where they arise. Parotid gland plasmacytoma is rarely described entity as initial presentation of multiple myeloma [1, 2]. Here we describe a patient who had clinical progression of multiple myeloma as parotid gland plasmacytoma. To our knowledge this is the first case described in literature where parotid gland plasmacytoma presented as clinical progression of multiple myeloma since parotid plasmacytoma was discovered before the diagnosis of multiple myeloma in all previous cases [3, 4]. Our patient is a 62-year-old female who was diagnosed with IgG kappa multiple myeloma 8 years ago and was previously treated with multiple chemotherapies including thalidomide, bortezomib and VAD (vincristine–adriamycin–dexamethasone) regimen, came to hematology clinic with slowly growing, painless mass in front of her right ear from past 3 months. On examination, this swelling was firm in consistency with smooth margins, non-tender, about 2 9 2 cm in size and appeared to be originating from parotid gland. No adenopathy was noted and examination of head and neck was otherwise unremarkable. A CT scan of soft tissue of neck was performed which showed a solid mass in right parotid gland which measured 2.5 9 2.0 cm with smooth margins and normal left parotid gland. Subsequently, a right superficial parotidectomy with conservation of facial nerve was performed. Histopathologic examination revealed glandular tissue with attached fibro-connective tissue with sheets of innumerous plasma cells consistent with extramedullary plasmacytoma (Fig. 1). Immunohistochemical studies for CD138, IgG and Kappa were strongly positive and were negative for IgM, IgA and Lambda consistent with previously diagnosed IgG kappa multiple myeloma (Fig. 2). Patient’s blood tests including immunoelectrophoresis and quantitative immunoglobulins did not show any significant differences when compared to the blood tests which were conducted 7 months ago. A total body skeletal survey was performed which showed generalized osteopenia, endosteal scalloping and wedge deformities in multiple vertebrae, but there was no evidence of bony lytic lesion or any other bony progression. This patient did not undergo chemotherapy or radiotherapy after parotidectomy as there was neither biochemical nor bony progression of multiple myeloma. Multiple myeloma can be present as plasmacytoma at the time of diagnosis [4] or at the time of subsequent relapse during the course of disease. Disease recurrence is commonly seen in medullary sites, but extramedullary sites are increasingly becoming common. To our knowledge this is the first case described in literature where parotid gland plasmacytoma presented as clinical progression of multiple myeloma. This case also reiterates the importance of physical exam in patients with hematological malignancies.