Introduction
Plasma cell tumor is a rare plasma cell neoplasm that manifests as solitary or multiple masses within the axial skeleton or soft tissue structures, with no systemic involvement. It represents an early-stage plasma cell malignancy and is considered an intermediate stage between monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) [ 1 ]. According to the International Myeloma Working Group, plasma cell tumors can be classified into two primary categories [ 2 ]: solitary plasmacytoma and multiple solitary plasmacytomas (MSP). Furthermore, solitary plasmacytoma can be subdivided based on the origin of the plasma cells: solitary bone plasmacytoma (SBP) when originating from bone marrow plasma cells, and extramedullary plasmacytoma (EMP) when arising from plasma cells located on mucosal surfaces.
The etiology of plasmacytoma remains ambiguous [ 3 ]. Nevertheless, it is hypothesized that EMP might be induced by inhalation of chemicals, chronic irritation, excessive irradiation, viral infection, and genetic disorders within the reticuloendothelial system [ 4 ]. Plasmacytoma is a rare disorder, with the annual incidence of solitary plasmacytoma being lower than 450 cases. EMP constitutes 4 % of all plasma cell malignancies [ 5 , 6 ]. It is more prevalent among the elderly, with an average age of 55 years, and predominantly affects men, with a male-to-female ratio of 3:1 [ 5 ]. EMP can occur in any part of the body, with 80 %–90 % emerging in the head and neck as well as the respiratory and digestive tracts [ 7 ]. It mainly occurs in the oral cavity, tonsillar fossa, nasal cavity, and paranasal sinuses, presenting as headache, rhinorrhea, dysphagia, sore throat, epistaxis, and nasal congestion. Nevertheless, it can also arise in the gastrointestinal tract, breast, testis, skin, and lungs. EMP occurring in the lungs is referred to as primary pulmonary plasmacytoma (PPP) [ 8 ].
PPP is regarded as an extremely rare tumor [ 9 ] and can originate from different sections of the airway, such as the trachea, bronchi, or lung parenchyma. Patients typically present with non-specific symptoms related to the size and location of the tumor, such as dyspnea, cough, and hemoptysis. The literature on intrabronchial plasmacytoma is limited [ 10 ], and few cases have been documented. Surgical resection is typically the first-line therapeutic approach. Additionally, radiotherapy serves as an adjunct or standalone treatment in some cases.
In this report, we present a case of a 69-year-old female diagnosed with intratracheal plasmacytoma, who manifested respiratory distress and was successfully diagnosed and resected via endoscopy. She received local radiotherapy after the surgery, and there was no evidence of local recurrence during the follow-up. This case report has been presented in accordance with the CARE (CAse REport) reporting guidelines.
Case report
A 69-year-old female patient with a history of hypertension but no smoking history presented to our hospital with progressive dyspnea over a 2-year period and acute exacerbation within the preceding day. On admission, she was in severe respiratory distress with an oxygen saturation level of 85 %. An urgent chest computed tomography (CT) scan ( Fig. 1 A–D) was immediately performed, revealing a nodular lesion within the trachea measuring approximately 15 mm in diameter, characterized by prominent calcification. The boundary between the lesion and the tracheal wall was indistinct, and the lesion demonstrated mild to moderate enhancement following contrast administration.
Fiberoptic bronchoscopy ( Fig. 2 A–D) revealed that the lesion was located approximately 5.7 cm from the glottis, with a longitudinal diameter of approximately 2.0 cm, and the tracheal lumen was narrowed by approximately 90 %. Urgent endoscopic tumor ablation was performed using techniques such as electrocautery snaring, electrocautery resection, argon plasma coagulation, and laser ablation of calcified lesions to remove the affected tissue. Two endoscopic tumor debulking procedures were conducted at one-week intervals. Postoperatively, fiberoptic bronchoscopy demonstrated that the degree of bronchial lumen stenosis was reduced to approximately 10 %, and the patient's dyspnea symptoms were significantly alleviated.
The pathological and immunohistochemical findings of the fiberoptic bronchoscopy biopsy are summarized as follows ( Fig. 3 A–D): Diffuse proliferation of plasma cells with uniform morphology was observed. Immunohistochemical analysis revealed the following markers: CD38 + , CD138+, μ+, λ-, MUM-I+, OCT-2+, BOB-1+, Ki-67 (5 %), EMA+, CD3 − , CD20 − , CD79a-, CD43 − , CI56-, IgG+, VIM+, Cyclin D1-, CD34 − , P63-, CD21 − , IgG4-, IgM (scattered +), IgD-, Kappa+, Lambda+, Congo red staining (+), and in situ hybridization for EBER (−). Based on these immunohistochemical results, extramedullary plasmacytoma cannot be excluded.
To further clarify the diagnosis, immunofixation electrophoresis was performed on the patient, revealing normal IgG, IgM, IgA, K, and λ polyclonal bands. Serum protein electrophoresis results were as follows: albumin 51 %, α1-globulin 3.2 %, α2-globulin 12.6 %, β-globulin 13.8 %, and γ-globulin 19.8 %. Urinary Bence-Jones protein testing demonstrated the following: urinary immunoglobulin light chain K < 7.16 mg/L, urinary immunoglobulin light chain λ < 3.94 mg/L, with a urinary K/λ ratio of 1.82. Bone marrow puncture analysis revealed a karyotype of bone marrow cells as 46,XX [20]. Immunophenotyping for multiple myeloma showed no evidence of cells with abnormal immunophenotypes. Whole-body PET-CT ( Fig. 4 A–B) revealed symmetrical increased glucose metabolism in the bilateral palatine tonsils, with a maximum SUV value of approximately 4.1, considered physiological uptake. Post-surgical evaluation of the tracheal lesion demonstrated localized soft tissue density within the inner wall of the trachea at the surgical site, accompanied by a high-density shadow and increased 18F-FDG uptake, with a maximum SUV value of 3.6. Multiple lymph nodes were observed in the mediastinum, some with slightly higher density; the largest measured approximately 11.8 mm in long diameter, with clear boundaries and no increased 18F-FDG uptake, suggesting inflammatory lesions. Based on the comprehensive findings from all auxiliary examinations, the patient was definitively diagnosed with isolated extramedullary plasmacytoma of the trachea.
One month later, the patient underwent a follow-up chest computed tomography (CT) scan, which demonstrated residual lesions with no significant increase compared to the postoperative state. To further manage the condition, local radiotherapy was administered at the lesion site. Simulation-enhanced CT was used for precise positioning, and the target area was carefully delineated. The gross tumor volume (GTV) included the tracheal wall lesion and intratracheal involvement. The clinical target volume (CTV) was defined as GTV extended by 1 cm superiorly and inferiorly and 0.5 cm anteriorly, posteriorly, and laterally (with adjustments based on anatomical relationships), while the planning target volume (PTV) was expanded from CTV by an additional 0.5 cm margin. The prescribed dose was 95 % of the PTV at 45 Gy delivered in 25 fractions of 1.8 Gy each. Normal tissue doses remained within acceptable limits. A total of 24 radiotherapy sessions were completed, and the patient tolerated the treatment well. Grade I radiation-induced tracheitis was observed during the course of therapy. Following the completion of radiotherapy, a follow - up lung computed tomography (CT) examination revealed a notable reduction in the lesion. The size of the tumor decreased from 1.5 × 2.0 cm 2 prior to treatment to 0.3 × 1.0 cm 2 . The patient recovered satisfactorily from both the respiratory interventional procedure and radiotherapy. Regular follow-up examinations were conducted over a period of approximately 24 months ( Fig. 5 A–D), with routine monitoring. No evidence of recurrence or metastasis was detected during this time.
Discussion
Solitary extramedullary plasmacytoma (EMP) of the trachea is an exceptionally rare condition. As reported in the literature [ 11 ], due to its anatomical origin and location, it is often associated with airway obstruction or irritation, manifesting as coughing, shortness of breath, or dyspnea. However, some patients may remain asymptomatic, leading to potential misdiagnosis as bronchial asthma due to overlapping clinical features. Pulmonary plasmacytomas are predominantly managed through surgical resection, radiotherapy, or palliative bronchoscopic interventions. In this case report, we present a solitary intratracheal EMP detected in a 69-year-old female patient. The lesion was maximally debulked via bronchoscopy and subsequently treated with localized radiotherapy at the lesion site. During follow-up, no evidence of recurrence was observed.
When plasma cell neoplasms are suspected, the following markers should be considered for detection: CD3, CD20, CD38, CD138, MUM-1, Ki-67, κ (Kappa), and λ (Lambda). In most cases, plasma cell neoplasms do not express CD20 but typically exhibit expression of CD38, CD138, and MUM-1. Among these markers, CD138 demonstrates relatively high specificity, although its sensitivity is somewhat limited. In certain tumors with plasma cell differentiation, it is possible to observe a scenario where CD3, CD20, CD38, and CD138 are all negative, while only MUM-1 shows diffuse and strong positivity. Therefore, the importance of MUM-1 detection in the differential diagnosis of plasma cell neoplasms should not be underestimated. Typically, the Ki-67 index in classical plasma cell neoplasms is relatively low, ranging from 10 % to 30 %. In contrast, the Ki-67 index in anaplastic plasma cell neoplasms and plasmablastic lymphomas generally exceeds 50 %. To differentiate between proliferative or reactive plasma cell conditions, the clonality of plasma cells can be assessed by detecting the ratio of κ (Kappa) and λ (Lambda) light chains. A polyclonal distribution suggests a reactive lesion, whereas a monoclonal distribution indicates a plasma cell neoplasm.
A systematic review of the literature on extramedullary plasmacytoma (EMP) [ 12 ] indicates that solitary plasmacytomas commonly occur in bone and soft tissue. Specifically, the axial skeleton is the most frequent site for bony involvement, while the head and neck region and upper aerodigestive tract (UADT) are predominant sites for soft tissue involvement. EMP predominantly affects men aged between 40 and 77 years. The primary treatment modalities for EMP include surgery, radiotherapy, and chemotherapy. When the lesion is localized and surgically resectable, surgical intervention is preferred; for smaller lesions, local radiotherapy may also be considered. For patients receiving a combination of surgery and radiotherapy, the median survival exceeds 300 months. In contrast, the median survival period is 156 months for those treated with surgery alone and 144 months for those receiving radiotherapy alone. Overall, among patients with EMP in the UADT, 61.1 % experienced no recurrence or progression to multiple myeloma (MM), 22.0 % had disease recurrence, and 16.1 % progressed to MM. Therefore, it is important to recognize that treatment with radiotherapy or surgery does not represent the endpoint of management; regular follow-up is equally critical. It is recommended that patients undergo follow-up evaluations every 3 months during the first year post-treatment, with subsequent intervals adjusted based on individual symptoms and treatment response.
This case represents a primary intratracheal extramedullary plasmacytoma (EMP). Given the patient's symptoms of respiratory distress and the location of the mass within the trachea, an urgent bronchoscopy and additional diagnostic evaluations were performed to formulate an appropriate treatment plan. The bronchoscopy demonstrated a large intratracheal mass causing near 90 % obstruction of the tracheal lumen. Subsequent biopsies confirmed the presence of a plasmacytoma. Therefore, it is essential to consider intratracheal plasmacytoma in the differential diagnosis of intratracheal masses. Due to the unique anatomical position of the tumor, failure to address it promptly may result in severe complications, including asphyxia. Consequently, lesions with significant airway obstruction should be managed as emergencies. Traditional therapeutic modalities such as surgery, radiotherapy, and chemotherapy may not be sufficient in these cases. Endoscopic tumor debulking surgery can rapidly restore airway patency and alleviate airway obstruction, playing a critical role in improving quality of life and extending survival.
The diagnosis and treatment of EMP require a thorough evaluation of the patient's clinical condition, including radiological imaging, bronchoscopic examination, and histopathological analysis. The choice of treatment modality depends on the patient's specific condition and overall health status; it typically involves either surgical resection or radiotherapy, both of which are considered effective options, particularly for elderly patients. Rigorous monitoring and systematic follow-up are essential for identifying potential recurrences and ensuring favorable long-term outcomes for patients.
In this case report, we describe a rare instance of isolated intratracheal plasmacytoma in a 69-year-old female, characterized by severe airway stenosis and progressive respiratory symptoms. This case highlights the importance of considering endobronchial plasmacytoma in the differential diagnosis of intratracheal masses, particularly in patients with obstructive symptoms and no identifiable alternative etiologies. The successful treatment of this patient via endoscopic tumor debulking resulted in significant improvement in respiratory symptoms, underscoring the efficacy of surgical intervention in such cases. Given the rarity of endobronchial plasmacytoma and its potential for severe clinical manifestations, clinicians must maintain a high index of suspicion and conduct a thorough diagnostic evaluation, including bronchoscopy, imaging studies, and histopathological analysis. The favorable outcome observed in this patient underscores the critical role of early diagnosis and timely intervention in achieving optimal management. Regular follow-up is essential for monitoring recurrence or disease progression, ensuring sustained patient health, and addressing any emerging concerns promptly.
CRediT authorship contribution statement
Man Wang: Writing – original draft, Conceptualization. Lu Liu: Investigation. Shihuan Yu: Writing – review & editing.
Statement of informed consent
All patient-related information that could lead to identification (including images, case data, etc.) included in this study was obtained with the written informed consent of the patients. Furthermore, explicit permission for its use in academic publications has been granted by the patients.
Consent to publish declaration
All co-authors have reviewed and formally consented to the academic publication of this manuscript.
Statement of the institutional review board
Not applicable.
Data availability statement
All data are available from the corresponding author upon request.
Funding
The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Wu Jieping Medical Foundation (320.6750.2021-04-22).
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment
The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Wu Jieping Medical Foundation (320.6750.2021-04-22).
Handling Editor: DR AC Amit Chopra
Contributor Information
Man Wang, Email: wangman@hrbmu.edu.cn.
Lu Liu, Email: liulu@hrbmu.edu.cn.
Shihuan Yu, Email: yushihuan2000@126.com.
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Associated Data
Data Availability Statement
All data are available from the corresponding author upon request.