A massive swelling of the neck mimicking parotid tumour

Clinical History

A 48-year-old male patient complained of a swelling on the left side of the face for the past 3 years. It was progressively increasing in size. The swelling was approximately 20x20 cm in size, firm to hard, non-tender and non-fluctuant extending from the left parotid region to the left supraclavicular region.

Imaging Findings

An ill-defined, heterogeneous enhancing soft tissue lesion (measuring 11.1x18.6x16.7 cm) with necrotic areas is seen in the left cervical region. Superiorly the lesion extends up to the level of the mastoid process and external auditory canal with upward displacement of the parotid gland. Inferiorly the lesion extends to the supraclavicular region with compression of the left subclavian artery and vein. Medially the lesion abutts and displaces the left lobe of the thyroid. The lesion extends into the submandibular region with compression and infiltration of the submandibular gland. The interface with the masseter and medial pterygoid muscles is ill-defined. The left common carotid artery is medially displaced by the lesion with encasement of internal and external branches and the left internal jugular vein is compressed. The left sternocleidomastoid muscle is infiltrated by the lesion and the interface with trapezius and splenius capitis muscles is ill-defined. Posteriorly the lesion is extending into paravertebral soft tissues.

Discussion

Lymphomas are a heterogeneous group of disorders resulting from malignant transformations in the lymphocyte cell lines [1, 2]. Lymphomas generally originate either from stem B cells, T cells or histiocytic cells [1].They are the second most common tumours in the head and neck region [3] and second most common site for extranodal lymphoma. They can involve orbit, paranasal sinuses, Waldeyer's ring, salivary glands and thyroid [4]. 50% of all lymphomas occur in the head and neck region [2]. The lymphomas are mainly classified as Hodgkin’s (HL) or Non-Hodgkin’s (NHL) type, either of B-lymphocyte or T-lymphocyte origin [2], however, WHO have classified both HL and NHL in subtypes. HLs involve the lymph nodes predominantly and only approximately 5% arise in extranodal sites whereas 30% of NHLs present in extranodal sites. HL is most commonly located in the lymph nodes of the neck and mediastinum [5]. Malignant lymphomas occur in both sexes but predominantly in men [6]. The pathological hallmark of Hodgkin's lymphoma is Reed-Sternberg cells. NHL is five times more frequent than HL in the head and neck region [7]. The diffuse large B-cell lymphoma (DLBCL) is the most common type of primary oral and para-oral NHL [8] encountered in the paranasal sinuses, mandible, maxilla, and Waldeyer ring [5]. Lymph nodes of HL and NHL are homogeneous and vary in size from 2 to 10 cm [5]. Computed tomography and bone marrow biopsy is the mainstay of staging for oropharyngeal lymphoma and other nodal lymphomas, however, positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) and computed tomography (PET/CT) is a useful method for staging and assessment of therapeutic response [9]. Lymphomas are isodense to muscle on CT and circumscribed with distinct margins that display extranodal extension with less-well-defined margins and areas of necrosis within the tumour matrix. On MRI, T1-weighted images of lymphomas shows low signal intensity and low to high signal intensity on T2-weighted images with mild enhancement after injection of Gadolinium-DTPA (Gd-DTPA) contrast material [5]. In our case the diagnosis was established on the basis of both imaging findings and histopathology of the biopsied tissue from the lesion.

Differential Diagnosis List

Final Diagnosis

Hodgkin's lymphoma

URL:	https://www.eurorad.org/case/11922
DOI:	10.1594/EURORAD/CASE.11922
ISSN:	1563-4086