Case history

A 30 year old student presented to an accident and emergency department with peluritic chest pain of six days' duration. He was previously well with no medical or surgical history. He was on no medication. Examination was unremarkable. An electrocardiogram was performed and this was normal. Figures 1 and 2 show the chest x ray film and the computerised tomography scan that were subsequently performed.

Questions

(1) What does figure 1 show?
(2) What is the differential diagnosis?
(3) What does figure 2 show and how can a definitive diagnosis be reached?

Answers

(1) Figure 1 shows mediastinal widening, most prominent in the superior mediastinum.
(2) For descriptive convenience, mediastinal masses are conventionally divided into three compartments: anterior, middle, and posterior. The first step in evaluating a mass is to place it in one of these compartments. For example, lymphoma and sarcoidosis can look very similar. However, the presence of anterior mediastinal nodes distinguishes the former from the latter. The most common lesions in the anterior compartment are thyroid masses, thymomas, lymphomas, and teratomatous neoplasms. In the middle compartment lymph node enlargement (due to infection, autoimmune disease, metastases, granulomatous disease, lymphomas), vascular masses, and pleuropericardial and bronchogenic cysts are the most abundant lesions. Neurogenic tumours, paravertebral abscesses, paravertebral tumour extension, oesophageal lesions, and aortic aneurysms form the bulk of the masses seen in the posterior compartment.
(3) This is a computerised tomography scan of the chest showing mediastinal lymphadenopathy. The definitive cause of the lymphadenopathy can be established using percutaneous fine needle aspiration biopsy, or mediastinoscopy with biopsy of the mediastinal lymph nodes. On this occasion mediastinoscopy with biopsy was performed which showed Hodgkin's lymphoma.

Discussion

The lymphomas are malignant proliferations of cells of the immune system. They are relatively uncommon, accounting for about 5% of all malignant disease in adults. Their aetiology is largely unknown although associations with infectious agents (for example, Helicobacter pylori, Epstein-Barr virus), immunodeficiency states (for example, HIV infection), autoimmune disorders, ionising radiation, carcinogenic chemicals, and inherited disorders (for example, ataxia, telangiectasia, xeroderma pigmentosum) have been established.

They are historically divided into Hodgkin's and non-Hodgkin's lymphomas. Hodgkin's disease is a rare malignancy with Caucasians showing incidence peaks in early adulthood and old age. Non-Hodgkin's lymphoma is a much commoner heterogeneous group of malignant diseases. The Ann Arbor system is used for staging both types of lymphomas, although it is less relevant for the latter because the prognosis is based more on histological type than on stage. Non-Hodgkin's lymphoma is usually divided, according to histologic appearance, into low grade and high grade disease. The former is indolent and while responsive to treatment is incurable. The latter is much more aggressive but is very responsive to treatment and is potentially curable. For both types of lymphoma, increasing age, presence of systemic symptoms (fever of 38^oC or more, weight loss of more than 10% of body weight, drenching sweats), and higher stage confer a poorer prognosis.

Compared with Hodgkin's disease, non-Hodgkin's lymphoma tends to present with a higher stage, to have a non-contiguous pattern of spread, and to affect older patients. Histological examination of a biopsy sample is needed to definitively distinguish between the two types of lymphoma. Multinucleated Reed-Sternberg cells are a diagnostic feature of Hodgkin's disease.

In Hodgkin's disease radiotherapy alone or in combination with chemotherapy is used for local disease and chemotherapy for disseminated disease. The five year survival is 50-90%, depending on stage and histological type. Non-Hodgkin's lymphoma is usually more generalised and thus treated with chemotherapy, although radiotherapy may be used for localised disease. The five year, disease free survival of patients with high grade non- Hodgkin's lymphoma depends on the histological subtype and varies from 30-60%. Stem cell or bone marrow transplantation may be used in some patients. Though low grade lymphomas respond to chemotherapy and radiotherapy, the disease cannot be eradicated. But median survival generally approaches 10 years because of the indolent nature of the disease.