Radiotherapy in Extramedullary Plasmacytoma of the Tongue with Nodal Involvement: A Case Report with One-Year Follow-Up

Abstract

Tongue extramedullary plasmacytoma (EMP) with regional lymph node metastases is a very rare pathology. Despite being a rare entity, extramedullary plasmacytoma should be considered a differential diagnosis in cases of a mass or ulcer in the tongue. A 60-year-old lady presents with an ulcerative lesion over the right lateral border of the tongue with dimensions 3.5 × 2 cm for one year. Initially, on histopathological examination, a possibility of plasma cell neoplasm was suspected; on further IHC, serum protein electrophoresis, and radiological investigations, a definite diagnosis of solitary EMP of the right lateral border of the tongue with regional nodal metastases was confirmed. The patient received radiotherapy for the primary disease along with the involved neck nodal sites.

Introduction

Solitary plasmacytoma and extramedullary plasmacytoma (EMP) are rare malignancies, accounting for about three percent of all plasma cell neoplasms. While they can originate at any extramedullary site, EMPs account for 4% of all upper respiratory tract non-epithelial tumors [1]. The diagnosis of EMP is made by excluding multiple myeloma and by the absence of monoclonal protein in the serum or urine in conjunction with normal findings on both radiological evaluation and bone marrow biopsy. The risk of regional lymph node metastases in solitary EMP is very rare. Radiotherapy plays a pivotal role in the treatment of extramedullary plasmacytoma, even though the role of elective lymphatic irradiation is still a matter of debate. A five-year local control rate after radical treatment range between 80 and 95% has been reported to date; with an overall survival of 90 to 100% [2].

In a literature review, by Xiaoli Zhu et al. 22 patients with EMP were reported among which 17 patients were having primary EMP in the head and neck region with none of the patients having locoregional lymph node metastases [3]. According to Quian Zhu et al., about 10–15% of EMP are associated with regional lymphadenopathy and it is associated with poor prognosis [4].

We report a case of solitary EMP of the tongue with regional lymph node metastases who received radiotherapy to the primary site and involved nodes and showed complete response after treatment.

Case

A 60-year-old woman presented with a two-year history of recurrent pain in the right side of her tongue and an associated loss of taste sensation. During the previous three months, she developed tongue ulceration with surrounding induration. Her family history was unremarkable. Physical examination revealed a tender, superficial, erosive ulceration on the right lateral border of the anterior tongue with normal tongue movements while the rest of the physical examination was normal. An incisional biopsy and histopathologic examination revealed a dense inflammatory infiltrate comprising predominantly of plasma cells and mature lymphocytes. Immunohistochemistry demonstrated light-chain restriction. The tumor cells were negative for CD20, and positive for kappa light chains, lambda light chains, and CD38. These findings were consistent with a diagnosis of a plasma cell neoplasm. A complete workup for multiple myeloma was carried out. The investigation included a Positron-emission tomography (PET) scan (Fig. 1a), bone marrow biopsy, serum, and urine protein electrophoresis, and measurements of the erythrocyte sedimentation rate and levels of β2-microglobulin, quantitative immunoglobulins, and Bence Jones proteins in the urine. Positron-emission tomography (PET) detected a lesion over the right lateral border of the anterior tongue with bilateral level II cervical lymphadenopathy. Fine needle aspiration cytology (FNAC) from the level II cervical node showed plasma cells.

Fig. 1.

a Pre-radiotherapy PET CT image showing primary disease with involved lymph nodes b Post radiotherapy PET CT image showing complete metabolic response

She was treated with three-dimensional conformal radiotherapy with a total dose of 50 Gy in daily fractions of 2 Gy five days a week for a total of five weeks (Fig. 2a and b). Lymph node metastasis had been found, so we performed nodal irradiation. At the end of treatment, the patient exhibited acute Radiation Therapy Oncology Group (RTOG) grade two mucositis with edema of the tongue and grade one dry desquamation of the cheeks; these conditions resolved within a week with appropriate medications.

Fig. 2.

a Contouring section on CT scan CTV (Clinical Target Volume) primary (Pink), CTV nodal (Blue) b CTV taken for the radiotherapy treatment

After three months of follow-up, the ulcerations on the right side of the tongue had disappeared and the patient showed no sign of systemic myeloma or local recurrence. On further follow-ups at 6, 9, and 12 months, no clinic radiological evidence of disease is found (Fig. 1b).

Discussion

Plasma cell neoplasms account for approximately 1–2% of human malignancies, the incidence of solitary bone plasmacytoma (SBP) is 40% more than EMP, with SPB constituting 2 to 5% of all plasma cell malignancies and EMP constituting 4% of all plasma cell malignancies [5]. Typical clinical signs are focal submucosal masses or swelling. Given the limitations of physical examination, MRI and computed tomography can help delineate the extent of lesions, and PET can help show lymphatics or distant metastasis.

Diagnosis of plasmacytoma is based on histology and immunohistochemistry results. Histology shows a dense and uniform infiltration of plasma cells. Amyloid deposits have been observed in 15–38% of extramedullary plasmacytoma cases [6]. Immunohistochemical findings are important in differentiation because reactive plasma cell infiltrates are histologically similar to plasmacytoma. Confirmation of the diagnosis of extramedullary plasmacytoma requires exclusion of the diagnosis of multiple myeloma by serum protein electrophoresis, urine Bence Jones protein analysis, skeletal examination, and bone marrow biopsy.

Localized extramedullary plasmacytoma is highly sensitive to radiation. According to published guidelines, the recommended first-line treatment for extramedullary plasmacytoma is definitive radiation therapy, which is the recommended first-line treatment for extramedullary plasmacytoma to achieve local control. Due to the small number of patients in the reported series and the low local failure rate, there is no firmly established dose–response relationship. Tsang et al. At 35 Gy achieved local control in 13 of 14 patients (92.9%) [7]. One of the patients who failed radiotherapy had a primary tumor larger than 5 cm. Jyothirmayi et al. achieved local control at doses of 35–45 Gy in 6 of 7 patients (85.7%) (Median: 40) delivered in 20 fractions [8].

The optimal target for radiation therapy volume is equally controversial. Extramedullary plasmacytoma of the upper aerodigestive system (> 80% of cases) has a very low chance of metastasizing to the cervical lymph nodes [9]. The inclusion of draining cervical lymph nodes in the radiation field increases the likelihood of acute and late morbidity, especially xerostomia. Favorable results have been reported in series that included cervical lymph nodes only when clinically relevant. So elective nodal irradiation in node-positive plasmacytoma tongue can be omitted.

Conclusion

Extramedullary plasmacytoma of the tongue with cervical lymph node involvement is very rare. It may be misdiagnosed as either a benign reactive process or a lymphoma. Awareness of this entity may help prevent misdiagnosis and avoid its progression to multiple myeloma and consequent loss of curability. In our patient, irradiation to the primary site with involved nodes achieved local control without causing significant morbidity.

Declarations

Conflict of Interest

The authors report no conflicts of interest related to this study.