- Lymphoma is a common disease of the head and neck.
- Lymphoma most often presents as nodal disease.
- In its extranodal varieties, it takes on appearances that mimic other pathologies.
- Angiocentric and angiotropic lymphoma are forms that may commonly be mistaken for other pathology.
- Differentiation of lymphoma from reactive or proliferative but benign lymphoid processes is often difficult based on imaging findings.
Prevalence and Etiology
Lymphoma is a relatively common malignancy of uncertain precise etiology. It has associations with disorders such as HIV and Epstein-Barr virus infection but no definitive causative relationship.1,2 The disease affects all age groups but is most common in young to middle-aged adults.3
In general, it is difficult to determine the frequency of lymphoma arising primarily in, or strictly limited to, the head and neck region. Often, head and neck lymphoma is part of systemic involvement. However, the head and neck region may be the site of presenting complaints in secondary as well as primary disease. The best known presentation is probably cervical adenopathy; however, lymphoma can mimic most infiltrating highly cellular malignancies at any particular site. It is probably best to also consider the chronic leukemias in this context from a morphologic and spread pattern perspective since their nodal presentation cannot be distinguished from lymphoma, but these are not lymphomas and not part of the classification. The nodal expression of this disease is considered in more detail in conjunction with reactive and lymphomatous lymphadenopathy in Chapter 158.
The patterns of disease spread described in the following material will apply across lymphoma that involves in all anatomic regions of the head and neck.
PATTERNS OF DISEASE AND PATHOLOGY
The debate of how to classify lymphomas is well beyond the scope of this text. For a simple and reasonable approach, the fundamental separation of types used by the Lukes-Collins Revised Classification and Revised European-American Lymphoma (REAL) Classification is used here. The non-Hodgkin types are separated into T-cell and B-cell groups. Hodgkin disease is then the third major group.
Almost all of these diseases express themselves in the head and neck region often just as nodal disease. Some, like the chronic leukemias and Hodgkin disease, present almost entirely as nodal disease. Many also involve extranodal sites. It is the extranodal disease that is often most challenging to diagnosis correctly since the variable sites, morphology, and propensity for perineural and perivascular spread of some types of lymphoma make its presentation at extranodal sites protean.4 For this reason, lymphoma should enter the differential diagnosis of an infiltrating process in the head and neck when the disease morphology appears “unusual” for want of a better term or the pattern is multifocal and possibly perineural and perivascular (Figs. 27.1 and 27.2).
Immunocytochemical phenotyping and molecular genetics have altered the management of lymphoma and related necrotizing sinonasal diseases discussed in Chapter 92 as well as their differentiation from diseases such as Wegener granulomatosis or sarcoidosis. Terms like polymorphic reticulosis and lymphomatoid granulomatosis are also no longer used. The majority of these previously pathologically poorly understood entities are now known to be sinonasal lymphomas of B-cell lymphoma, T-cell lymphoma, and natural killer (NK)/T-cell lymphoma with a broad range of biologic activity depending on their immunophenotype. NK/T-cell lymphoma is strongly associated with the Epstein-Barr virus. The locoregional failure rates in these tumors are similar; however, distant failure is much more common in B-cell or NK/T-cell lymphoma than in T-cell lymphoma. T-cell lymphoma has the most favorable prognosis, and NK/T-cell has the worst.
Extranodal Disease Trends in B-Cell Lymphoma
In general, the extranodal sites of interest include the lacrimal glands (Fig. 27.3) and other contents of the orbits (Figs. 27.2 and 27.4), nasal cavity and sinuses (Fig. 27.5), the parotid glands (Figs. 27.6 and 27.7), the Waldeyer ring (Figs. 27.8 and 27.9), and thyroid gland (Fig. 27.10). Unusual sites of presentation include the canine fossa of the cheek, the buccal space, and the infratemporal fossa likely due to at least some relationship to the facial nodes and related lymphoid elements in these locations (Figs. 27.2 and 27.11), as discussed in Chapter 149. Disease in the larynx and trachea is rare (Figs. 27.12). As an example of potential uniqueness in an area where things tend to look the same, Burkitt lymphoma may be the most readily recognizable B-cell lymphoma due to its predilection for the facial bones and, particularly, the mandible (Fig. 27.13). Burkitt lymphoma also has both an extraordinary growth rate and an equally extraordinary tendency to respond quickly to chemotherapy.