High Grade Lymphoma Mimicking Advanced Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma represents the most common malignancy of the nasopharynx and central skull base, but the differential diagnosis of a nasopharyngeal mass should be broad. Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma, accounting for 30-40% of the 55,000 new cases of adult NHL diagnosed each year.1,2,3 Common head and neck sites of DLBCL include: Waldeyer’s ring, the nasal cavity, the paranasal sinuses, the thyroid and salivary glands, and the orbit while bone marrow involvement is a late finding.4 Typically lymphoma presents as a rapidly enlarging symptomatic mass at a single lymph node, however 10% of patients with NHL present with extranodal disease in the head and neck region.5 Lymphoma therefore must be considered in cases of extranodal or extralymphatic disease, even in the absence of nodal disease. In all, there are fewer than 30 reported cases of lymphoma presenting with isolated diffuse infiltration of the skull base.6,7,8 The peak incidence of DLBCL is in the seventh decade of life, but the process can occur at any age.4 Currently, there exists no effective screening modalities and patients are diagnosed only after they present with associated symptoms, such as lymphadenopathy. A CT scan in addition to a PET scan should be obtained to aid in staging and prognosis.9 Immunohistological staining is typically positive for CD 19, CD 20, CD 22, CD 45, and CD 79a, but negative for CD 3 and CD 5. Molecular rearrangements involving bcl-2 and bcl-6 are often seen in DLBCL.3,10 Analysis of gene expression profiles has enabled the identification of two molecularly distinct forms of DLBCL: germinal center B cell-like DLBCL, associated with significantly higher survival and activated B cell-like DLBCL (ABClike).3,11 A lesser studied third subgroup, Type III, serves to unify cases that do not express genes characteristic of either of the two more studied groups.3 Untreated, diffuse B-cell lymphoma is rapidly fatal (on the order of months) because of its aggressive progression. Surgical biopsy is imperative for diagnosis and is favored over fine-needle aspiration or large bore-needle biopsies because of the quantity of tissue needed for proper diagnosis.9 R-CHOP or cyclophosphamide, hydroxydaunomycin (doxorubicin), vincristine (Oncovin) and prednisone (CHOP) combined with rituximab, is the most commonly administered chemotherapy for DLBCL.1,2,9 Radiation therapy is adjunctive in cases of limited-stage disease.9 Prompt diagnosis and initiation of treatment often can reverse the cranial nerve palsies associated with primary lymphoma of the skull base and can be life saving. This case demonstrates the importance a broad differential diagnosis and thorough evaluation of the nasopharyangeal mass. Expeditious and accurate tissue diagnosis of a mass mimicking advanced nasopharyngeal carcinoma can be achieved safely in a minimally invasive endoscopic manner, as shown by this case. Although relatively uncommon, the nasopharyngeal mass requires a thorough evaluation. In an adult, the differential diagnosis is broad. Expeditious and accurate diagnostic studies and tissue diagnosis can have critical prognostic implications. We present the case of a man with high-grade lymphoma mimicking advanced nasopharyngeal carcinoma. The presentation, diagnosis and management of diffuse large B-cell lymphoma (DLBCL) in the head and neck are reviewed along with recent literature pertaining to the diagnosis and treatment of this aggressive lymphoma. INTRODUCTION