Abstract
Background
Extramedullary plasmacytoma is a rare plasma cell neoplasm of the soft tissues characterized by the presence of a single, discrete lesion without evidence of systemic disease. Extramedullary plasmacytoma may disseminate into multiple myeloma, a systemic plasma cell disease.
Methods
A rare case of extramedullary plasmacytoma of the cricoid cartilage with solitary plasmacytoma of the rib was reviewed.
Results
The patient was found to have two discrete lesions; one of the cricoid cartilage and one of the lateral left fifth rib. Despite the presence of multiple tumors, the patient was not diagnosed with multiple myeloma as the bone marrow appeared normal.
Conclusions
Due to the rarity of these neoplasms and the unusual localization of the extramedullary plasmacytoma tumor, a definitive diagnosis was difficult to make in this case. This case may be instructive for the differential diagnosis of laryngeal lesions.
1
Introduction
Plasma cell neoplasms can be classified into three major categories: multiple myeloma, extramedullary plasmacytoma, and solitary plasmacytoma of bone. These neoplasms represent approximately 1% of all malignancies of the head and neck region . Multiple myeloma results from abnormal B cell proliferation in the bones and bone marrow and is characterized by the presence of multiple bony lesions and plasma cell infiltration of the bone marrow . Multiple myeloma can damage multiple organ systems and lead to organ failure .
Extramedullary plasmacytomas are plasma cell tumors of the soft tissues and cartilage ; the most common sites of involvement are the aerodigestive tract and the oral cavity, although other sites have been reported . Patients with extramedullary plasmacytomas do not have evidence of multiple myeloma, although they may develop multiple myeloma as the disease progresses . Rather, these patients present with a single, discrete lesion of the soft tissue or cartilage and have bone marrow without significant plasma cell infiltration . Similarly, solitary plasmacytoma of the bone is characterized by a single bony lesion without evidence of bone marrow infiltration . These patients do not present with symptoms characteristic of multiple myeloma, such as hypercalcemia, anemia, or renal failure .
Extramedullary plasmacytoma of the cricoid cartilage is extremely rare , with fewer than 10 cases reported in the literature. Our case was particularly unusual because the patient was found to have an additional lesion in the left fifth rib, which was diagnosed as a solitary plasmacytoma of the bone. Despite the presence of multiple tumors, additional tests were non-diagnostic for systemic disease.
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Case history
A 72-year-old man presented to our voice clinic with a two-year history of progressive hoarseness and stridor. He also complained of dyspnea on exertion. Flexible fiberoptic laryngoscopy revealed bilaterally mobile true vocal cords and evidence of subglottic stenosis. No masses or other lesions were noted.
Initial computed tomography (CT) of the neck revealed an expansile lesion of the cricoid cartilage causing moderate glottic and subglottic narrowing ( Fig. 1 ). The lesion did not extend to the mucosal surface or invade the thyroid gland or cartilage. Diffuse thickening and enhancement of the posterior commissure were noted. None of the lymph nodes identified in either side of the neck met the criteria for significant adenopathy.
A core biopsy of the cricoid lesion was performed, and immunostains were performed. The biopsy revealed a few small foci of densely cellular infiltration by atypical plasma cells with perineural invasion and extension into the cricoid cartilage with accompanying necrosis. Immunohistochemical staining showed the presence of monoclonal plasma cells with kappa restriction, consistent CD138 expression, and scattered cytoplasmic IgD labeling, while IgG, IgA, and IgM were negative. All other immunostains were non-contributory.
Following core biopsy, a full-body positron emission tomography-CT (PET/CT) study was obtained. PET/CT images demonstrated the previously identified glottis mass with maximum standardized uptake value (SUV) of 7.5 ( Fig. 2 ). In addition, a fusiform expansile soft tissue lesion originating from the lateral left fifth rib, measuring 5 × 2 cm in axial cross-section with maximum SUV of 8.0, was identified ( Fig. 3 ). No other osseous or soft tissue lesions were demonstrated, and there were no radiographically significant or hypermetabolic lymph nodes. Glottic defect secondary to prior core biopsy is evident on the PET/CT images of the neck.
Subsequently, the patient was evaluated for multiple myeloma. Bone marrow biopsy revealed hypercellular marrow with tri-lineage hematopoiesis and mildly increased (5%–7%) plasma cells with kappa predominance. Blood tests did not reveal evidence of hypercalcemia, renal failure, or anemia. Serum immunoglobulin and β2 microglobulin levels were normal. Urine immunofixation showed a biclonal free kappa monoclonal protein. These results were not diagnostic for multiple myeloma. Given the imaging and pathologic findings, extramedullary plasmacytoma of the cricoid cartilage with solitary plasmacytoma of the rib is the most likely diagnosis.
Extramedullary plasmacytomas and solitary plasmacytomas of the bone are treated with surgery and/or radiation therapy . This patient was treated with two months of radiotherapy targeted to the two sites of disease involvement. He was followed up with PET/CT scans every six months and regular blood tests. A CT scan one year after presentation did not reveal any interval change in the volume of the residual soft tissue mass in the neck.
The patient has improved breathing and swallowing since completing radiotherapy. His hoarseness has also improved; however, he continues to experience some dyspnea upon exertion. He has not developed multiple myeloma at the time of publication.
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