Rare tracheal tumor: Solitary plasmacytoma.

Primary tracheal tumors are rare and trachea is an exceedingly rare site of extramedullary plasmacytoma (EMP). We report a case of solitary tracheal plasmacytoma causing symptoms of airway obstruction in a 59-year-old man. Flow/volume loop indicated the fixed central airway obstruction. Computerized tomography and bronchoscopy demonstrated a sessile tumor on posterior tracheal wall obstructing 80% of the lumen. Partial tracheal resection with T-T anastomosis was performed. Pathologic analysis of resected mass revealed EMP. Additional investigations excluded multiple myeloma. There are no signs of disease recurrence after 7-year follow-up.

Introduction

The extramedullary plasmacytomas (EMPs) are rare plasma cell tumors that arise outside of the bone marrow. They constitute around 4% of all plasma cell neoplasms and in 80% of cases occur in the upper aerodigestive tract-nasal cavity, paranasal sinuses, and oronasopharynx.[123] Trachea is a very rare site of plasmacytoma. Less than twenty cases were reported in the medical literature until 2013.[45] Durris et al. reviewed 18 cases of tracheobronchial plasmacytoma with tracheal location in 13 of them.[6] Others were single case reports. We report a case of solitary tracheal plasmacytoma causing symptoms of airway obstruction in a 59-year-old man.

Case Report

A 59-year-old male ex-smoker was admitted to our clinic with a 4-month history of nonproductive cough, stridor, and exertional dyspnea. Other constitutional symptoms and a laboratory workup were unremarkable. Flow/volume loop flattened in inspiratory and expiratory phases which indicated the fixed central airway obstruction. Chest X-ray was without pathologic finding. Thin-section multislice computerized tomography (MSCT) revealed an intraluminal polypoid mass, 15-mm in diameter, arising from the membranous part of the middle-third of the trachea occluding approximately 80% of the lumen. This exophytic tumor was sharply bordered and grew in contact with the tracheal cartilage, without evidence of cartilage invasion [Figure 1a]. Coronal and sagittal reformation showed the longitudinal extent of tumor; upper part was 3.5 cm distal to vocal cords [Figure 1b and c]. No lymph node enlargement was observed within the mediastinum. Virtual bronchoscopy demonstrated the severity of the airway narrowing [Figure 2]. Bronchoscopy confirmed MSCT finding-sessile tumor on posterior tracheal wall, starting from the third tracheal ring. Pathology report of tumor biopsy was not conclusive. The patient underwent surgery after adequate preoperative assessment and preparation. Partial tracheal resection 2.5 cm in length with termino-terminal anastomosis (interrupted sutures, prolen 3-0) was performed. The immediate postoperative course has been uneventful, with adequate anastomotic healing. Transient inferior laryngeal nerve palsy and dysphonia were present during several months after surgery. Pathologic analysis showed that infiltration was predominantly located in outer layer of tracheal wall, respiratory epithelium was reactively changed. No lymphoepithelial lesion was seen [Figure 3a]. Richly vascularized tumor nodule contained well-differentiated plasma cells as the major cell population [Figure 3b]. Plasmacytic origin of infiltration was confirmed by CD38 [Figure 4a] and CD138 [Figure 4b]. Monoclonality of plasma cells was confirmed by kappa light chain immunoglobulin expression [Figure 4c]. At the same time, lambda light chains of immunoglobulins were not expressed in the same cells [Figure 4d]. Based on tumor immunoprofile, a definite diagnosis of plasmacytoma has been established. Consequently, complete multiple myeloma (MM) workup was done. There were no lytic bone lesions on skeletal conventional X-ray examination. The results were normal for serum electrophoresis, and urine was negative for Bence Jones protein. Bone marrow aspirate and bone marrow biopsy showed normal morphology. Correlating the morphology, immunostaining of the tumor and clinical parameters, the diagnosis of MM was excluded, and solitary EMP was confirmed. Seven years after surgery, the patient is well, without dysphonia and symptoms, and signs of disease recurrence.

Figure 1

Axial computerized tomography scan (a) shows an intraluminal mass, 15-mm in diameter, arising from the membranous part of the middle-third of the trachea and obstructing the lumen. Coronal (b) and sagittal (c) reformation showed the longitudinal extent of tumor; upper part is 3.5 cm distal to vocal cords (blue line)

Figure 2

Virtual bronchoscopy shows spherical, smooth-surfaced tumor obstructing lumen of trachea (arrows)

Figure 3

Morphology: Monotonic cell population proliferation was detected in outer layer of tracheal wall (a); on higher magnification well-differentiated plasmacytic proliferation was seen (b)

Figure 4

Immunohistochemistry: Plasma cell origin of proliferation was confirmed by CD38 (a) and CD138 (b); only kappa light chain immunoglobulin expression was found in plasma cells (c); lambda light chain immunoglobulin expression was not found, and monoclonality of plasma cells was proven (d)

Discussion

Tracheal tumors as described in this case are uncommon and constitute around 1%–2% of all respiratory tract neoplasms and 0.1% of all malignancies. Two-thirds of all primary tracheal neoplasms are squamous cell carcinomas and adenoid cystic carcinomas; the remaining third is a diverse group composed of malignant, intermediate, and benign lesions.[15] Although most of EMP arise in upper airways, they are rarely present in trachea. They usually occur in 50–70 year-old patients and affect predominantly men.[16] Tracheal plasmacytoma, likewise, other tracheal tumors becomes symptomatic when narrows over 75% of the tracheal lumen as it was in reported case. Symptoms are nonspecific such as chronic cough, stridor, dyspnea, expiratory wheezing, hoarseness, or hemoptysis. They are often misdiagnosed as asthma or sleep apnea syndrome.[13678] Clinical diagnosis of tracheal extramedullary plasmacytoma before biopsy and histologic evaluation remains a difficult task. The diagnostic approach to those tracheal tumors was significantly changed by the introduction of computerized tomography (CT). CT with contrast enhancement and multiplanar reformations in sagittal, coronal, or oblique planes is useful for assessing the location of the tumor, degree and longitudinal extent of the luminal stenosis, the distance from the vocal cords and to the central carina, the airway wall, the mediastinal structures and the possible systemic spread. Virtual bronchoscopy can show a real-like view of the tracheal tumor with an excellent correlation with conventional optical bronchoscopy.[15] The bronchoscopy allows direct visualization of tumor, tissue sampling, and disease staging.

The final diagnosis is obtained by the histological examination which demonstrates proliferation of monoclonal plasma cells. Our opinion is that solitary plasmacytoma originated from extramedullary hematopoiesis in the field of osseal metaplasia of cartilaginous part of the tracheal wall. When an extramedullary plasmacytoma (EPT) is suspected, it is mandatory to exclude an MM and some kinds of non-Hodgkin lymphomas, particularly lymphoplasmocytic lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (lymphoma).[45]

Current treatment options of tracheal plasmacytomas include surgery or radiotherapy alone and surgery followed by radiotherapy.[19] As we did not have a preoperative diagnosis and the tumor was sessile, 1.5 cm in length and 3.5 cm distant from vocal cords without extratracheal propagation, we opted for radical resection. Resection margins were disease-free. The patient did not undergo any additional treatment. Even if the rate of progression to MM is low compared to solitary plasmacytomas of the bone, patients require careful monitoring and long-term follow-up. Local recurrence or a progression to MM has been described in up to 20% of cases [Table 1].[1610]

Table 1

Review of published cases of tracheal extramedullary plasmacytoma

Author	Age/sex	Treatment	Follow-up	Outcome
Dines et al., 1965[8]	60/male	LR	ND	No data
Kober, 1979[1]	69/female	ER+RT	ND	Multiple sequential plasmacytomas without progression to MM
Kairalla et al., 1988[3]	53/female	ER + laser+RT	2 years	Without local recurrence and progression to MM
Durris et al., 2002[6]	60/male	ER + cryotherapy + RT	16 months	Without local recurrence and progression to MM
Rai et al., 2003[9]	44/male	ER + RT	1 year	Without local recurrence and progression to MM
Wang et al., 2008[7]	38/male	LR	6 months	Without local recurrence and progression to MM
Garelli et al., 2011[2]	73/male	ER	1 year	Without local recurrence and progression to MM
Cuttitta et al., 2016[5]	51/female	LR + chemotherapy	2 years	Without local recurrence and progression to MM
Sukumaran et al., 2014[4]	39/male	RT	1 year	Local recurrence and new lesion in nasal cavity without progression to MM
Reyhan et al., 2005[10]	63/female	LR	1 year	Without local recurrence and progression to MM
Our case	59/male	LR	7 years	Without local recurrence and progression to MM

LR=Local resection, ER=Endoscopic resection, RT=Radiotherapy, ND=No data, MM=Multiple myeloma

Conclusion

Although extremely rare, extramedullary tracheal plasmacytoma should be considered as a differential diagnosis in cases of sessile tracheal tumors, detected on CT and bronchoscopy. Whenever possible, pathological evaluation of tracheal tumor should be made before treatment decision. Due to small number of cases, there is still no evidence-based approach to treatment-surgery and/or chemoradiation. Regardless of treatment option, annual follow-up, and evaluation for local recurrence or progression to MM is mandatory.

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Conflicts of interest

There are no conflicts of interest.