Non-hodgkin's lymphoma

(NHL), (Thomas Hodgkin, 17981866, English physician), a diverse group of diseases varying in radiological findings, clinical presentation and prognosis. In comparison to Hodgkins disease (HD), NHLs occur in older patients and are less common causes of thoracic disease. The histological classification of the NHLs has often been modified and is submitted to constant discussion. The Working Formulation for Clinical Usage that is the most recent classification, divides the NHLs on morphologic grounds, into three grades that correspond to prognosis: low, intermediate and high (Table 1). The dividing lines are not clearcut, and conversion from one grade to a more malignant grade often occurs. Intrathoracic disease is found at presentation in less than 50% of adult patients with NHLs.

Non-Hodgkin's lymphoma (NHL), Table 1. Working formulatoin classification of NHL.

The NHLs vary greatly in their initial presentation and aggressiveness. Low-grade NHLs occur mainly in older patients and produce widespread adenopathy at initial diagnosis. The patient frequently has no systemic symptoms. These lymphomas are relatively nonaggressive. Treatment may induce a temporary remission but these tumours generally recur. Some may progress to a more aggressive form. Others may undergo spontaneous remission. Intermediate and high-grade NHLs both present with enlargement of lymph nodes but frequently show extranodal disease. They occur in younger patients with localized disease. Most are treated for cure or at least long-term control, but unfortunately many of these lymphomas relapse within 2 years of initial treatment. NHLs may occur in immunocompromised patients, particularly transplant recipients and patients with AIDS. These lymphomas tend to be aggressive and to involve the central nervous system.

Radiologically, the appearance of intrathoracic involvement in NHLs is generally similar to that of Hodgkins disease (HD) (Fig.1). Chest wall involvement is much more common in NHLs as a result of direct extension of disease from the mediastinum. Occasionally, the chest wall is the primary site of extranodal lymphoma. It usually appears as a destructive lesion of a rib or vertebral body with a surrounding soft tissue mass. The pleura may be involved by a direct extension from a contiguous chest wall mass or pulmonary disease. The lung parenchyma is a common site of involvement by extranodal NLHs (see pulmonary lymphoma). In contrast to patients with Hodgkin's disease, the abdomen, pelvis and neck must be scanned in all patients with NHL as noncontiguous spread is common. Imaging techniques are also helpful in the posttreatment follow-up (see sterilized lymphoma and lymphoma recurrence thoracic).

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