Extranodal non-Hodgkin lymphoma of the head and neck.

Non-Hodgkin lymphoma (NHL) is the second most frequent malignant tumor in the head and neck, squamous cell carcinoma being the most frequent. NHL often appears in extranodal localisations. In the head and neck, two distinct extranodal sites are recognised: extranodal lymphatic localisations or involvement of the ring of Waldeyer, and extranodal extralymphatic localisations. In this study we reviewed the imaging features of 55 patients who showed extranodal NHL-localisations to investigate whether we could find specific imaging characteristics. There are no pathognomonic signs. However, if more than one extranodal mass is detected, if the mass appears huge without necrosis or ulceration, if the mass is associated with large, non-necrotic nodes, the diagnosis of non-Hodgkin lymphoma can be suggested; however, it is usually not possible to exclude other pathological processes with absolute certainty.