Management challenges of a rare case of the primary parotid gland non-Hodgkin lymphoma: A case report and review of the literature

Abstract

Diffuse large B-cell lymphoma is the most prevalent subtype of non-Hodgkin lymphoma (NHL), which makes up the majority of malignant lymphomas of the head and neck region. Lymphoma of the salivary gland is extremely rare. Most patients present with a unilateral, hard, non-tender mass that gradually enlarges over time. A thorough evaluation is necessary for a precise diagnosis because its clinical presentations are nonspecific, increasing the risk of misdiagnosis, leading to an inappropriate treatment plan, and ultimately delaying the optimal treatment of the disease. Imaging techniques like computed tomography scans and magnetic resonance imagings are part of the initial workup. Prior to biopsy, it can be challenging to differentiate NHL of the parotid gland from other tumors. Histological analysis and subsequent immunohistochemistry are essential for the definitive diagnosis. Systemic chemotherapy is the mainstay of treatment, while surgery and radiation may be necessary in some circumstances. Herein, we describe a 60-year-old man who had a steadily growing mass in his right parotid region. The pathology results confirmed it to be NHL, diffuse large B-cell lymphoma subtype. No similar lesions were found on clinical examination and subsequent radiological imaging. The patient received R-CHOP chemotherapy with impressive treatment outcomes. To date, at least 12 months of regular follow-up have passed since the patient completed oncological care; he remains free from signs and symptoms of the disease. This case points out the importance of considering lymphoma in the differential diagnoses when examining parotid neoplasms.

Keywords: Management challenges; NHL; head and neck tumors; parotid lymphoma.

Figure 1.

Photographs of the patient showing a huge right parotid mass before treatment (green arrow) (A), the mass extends inferiorly to the upper neck (green arrow) (B), presentations of the patient after oncological care (blue arrows) (C,D).

Figure 2.

The head and neck CT scans highlight a huge lobulated heterogeneous enhancing soft tissue tumor centered on the right parotid gland, extending to neck inferiorly (A). The huge mass is abutting the adjacent sternocleidomastoid, scalene and trapezius muscles giving the clinical impression of parotid gland malignancy (B). CT: computed tomography.

Figure 3.

Photomicroscopy of a fine-needle aspiration cytology smears from the parotid mass demonstrate scattered large atypical lymphoid cells with vesicular chromatin and prominent nucleoli, consistent with a large cell lymphoma, hematoxylin and eosin (H&E) staining at 40 x original magnification (A), histopathology of the biopsy from the parotid mass shows atypical lymphoid cells invading salivary gland tubules, H&E staining at 20 x original magnification (B); complete effacement and replacement of the salivary gland tissue by diffuse population of large atypical lymphocytes with vesicular nuclei, H&E staining at 20 x original magnification (C), diffuse strong membrane immunostaining of the tumor by CD20, IHC at 10 x original magnification (D).