An Endotracheal Plasmablastic Lymphoma

• Tracheal tumours encompass a small proportion of respiratory tract neoplasms, and tracheal lymphomas are very rare.

• Endotracheal plasmablastic lymphoma has never been described.

• Plasmablastic lymphomas can involve the trachea.

• Macroscopically, endotracheal plasmablastic lymphoma is indistinguishable from other more common causes of tracheal tumour occurrence.

Tracheal tumours encompass a small proportion of respiratory tract neoplasms, accounting for only about 2% of airway malignancies and with an incidence of 0.1 per 100,000 people per year [1]. Squamous-cell carcinoma is the most common tracheal tumour, followed by adenoid cystic carcinoma [1]. Symptoms are usually attributable to the intraluminal component of the tumour causing obstruction of the airway with stridor, dyspnoea, wheezing, haemoptysis, and cough.

The true incidence of secondary tracheal tumours, defined as tumours within the trachea but which do not originate from the trachea, is unknown. Tracheal involvement may occur because of direct invasion, or hematogenous or lymphatic spread, and the most common aetiologies are thyroid cancer, oesophageal tumour, and squamous-cell carcinoma of the lung [2].

Endotracheal lymphoma, albeit rare, has been reported, particularly polypoid nodules secondary to mucosa-associated lymphoid tissue (MALT) lymphoma [3].

A 40-year-old male smoker without any significant medical history presented with a 2-month history of a soft-tissue swelling of the right maxillary area, which persisted after teeth extractions. He was found to have a large ulcerative lesion involving the right maxillary alveolar ridge, with associated cervical lymphadenopathy. A biopsy of the maxillary lesion showed plasmacytic differentiation, with tumour cells exhibiting strong immunoreactivity, variable positivity with B cell markers, cytoplasmic κ light chain restriction, and the presence of Epstein-Barr virus (EBV, Fig. 1), all compatible with a diagnosis of high-grade B cell non-Hodgkin lymphoma (NHL), in particular plasmablastic lymphoma.

The patient was referred to our institution and subsequently found to be positive for human immunodeficiency virus (HIV) with a CD4 count of 69 cells/mm³. He was anti-retroviral therapy (ART)-naïve.

Routine staging positron emission tomography computed tomography (PET-CT) was performed and showed intense ¹⁸F-labelled fluoro-2-deoxyglucose (FDG) uptake in the known right maxillary tumour (Fig. 2a), with associated bony destruction. An endotracheal tumour measuring 14 × 11 mm (Fig. 2b), with less intense FDG uptake, was also noted. In view of the differential FDG uptake, a biopsy was advised.

The tumour appeared to be well-circumscribed and vascularised at bronchoscopy, with an appearance compatible with a primary tracheal tumour (Fig. 2c). Conventional fine-needle aspiration of the tumour did not yield diagnostic material (on rapid on-site evaluation), and forceps biopsies were subsequently cautiously obtained.

The histology of the endotracheal lesion also showed plasmacytic differentiation, with tumour cells exhibiting strong immunoreactivity with plasma cell-associated antigens as noted in the maxillary tumour, variable positivity with B cell markers, and the presence of EBV, all compatible with a diagnosis of plasmablastic lymphoma (Fig. 3). Of interest is the fact that the endotracheal tumour cells were more mature, with plasmacytic differentiation.

The levels of bone marrow aspirate, trephine, and serum calcium as well as renal function were normal, and the serum protein electrophoresis revealed a small polyclonal band. The patient was commenced on combination chemotherapy and ART, and has had a good clinical response to date.

Of people living with HIV, up to 40% will develop malignancy, with approximately 10% developing NHL [4, 5]. The most common systemic NHL subtypes seen in HIV-positive individuals are diffuse large B cell lymphoma (75%) and Burkitt lymphoma [6].

Plasmablastic lymphoma accounts for <3% of NHL seen in HIV-positive patients [7, 8]. It is a rare form of NHL that usually occurs in the oral cavity and these individuals are often positive for EBV [9, 10]. Involvement of the paranasal sinuses, skin, soft tissue, larynx, lung, and anorectal region have been described [11]. Tracheal involvement is exceptionally rare, and, to the best of our knowledge, has never been described.

Co-infection with Human herpesvirus 8 has also been reported in plasmablastic lymphoma, with a prevalence ranging from 17 to 100% [12, 13]. Another rare genetic subtype of plasmablastic lymphoma has rearrangements of the ALK tyrosine kinase gene.

A review of 157 cases of plasmablastic lymphoma reported that early clinical stage and complete response to chemotherapy are associated with a better outcome. The best approach to therapy remains unclear, and standard CHOP (cyclophosphamide,hydroxydaunorubicin [Adriamycin], vincristine [Oncovin], and prednisone or prednisolone) is considered an inadequate therapy [14]. The American National Comprehensive Cancer Network guidelines recommend a more intensive regimen, as at least 1 study has suggested better outcomes using more aggressive chemotherapy such as that used for Burkitt lymphoma [15].

In conclusion, plasmablastic lymphoma is an extremely rare form of HIV-related lymphoma, and endotracheal involvement is with plasmablastic lymphoma is not typically seen, which makes this possibly the first properly documented case.

We acknowledge the contribution made by Dr Candice Sher (Consultant Pathologist at Stellenbosch University) in the interpretation of the histology.

Written informed consent was obtained from the patient.

The authors have nothing to declare.

There was no funding.

E.M.T.B. and C.F.N.K. wrote the manuscript, which was then reviewed by all co-authors.