Hodgkin's disease, (Thomas Hodgkin, 1798 - 1866, English physician), is separated from the more common and more frequently fatal non Hodgkins lymphoma, by the presence of a distinctive histological feature, the Sternberg - Reed giant cell, a large reticulum cell with a tendency to form large, densely staining nuclei. Hodgkin's disease is classified into four subtypes in the Reye classification :
- Lymphocyte predominance (less than 5%) is characterized by the most favourable prognosis and an early stage disease presentation.
- Nodular sclerosis, the most common type (less than 75%) is associated with abundant fibrous tissue stroma. It is characterized by a less favourable prognosis than the lymphocyte predominant type. The mediastinum is usually involved.
- Mixed cellularity, the second most frequent type involves older patients and is characterized by a less favourable prognosis than the nodular sclerosis type. At presentation the stage of the disease is usually more advanced than nodular sclerosis.
- Lymphocytic depression, uncommon (less than 5%), is a variety with the worst prognosis. It involves older patients presenting commonly systemic symptoms and advanced disease.
Clinically, most patients present in their second or third decade with a secondary peak in the fifth or sixth decade. The currently accepted system of classification is the Cortwold's staging classification (Table 1).
Hodgkin's disease, Table 1. Cortwold's staging classification of Hodgkin's disease.
Involvement of a single lymph node region or lymphoid structure
Involvement of two or more lymph node regions on the same side of the diaphragm (the mediastinum is considered as a single site, whereas hilar lymph nodes are considered bilaterally); the number of anatomical sites should be indicated by a subscript (e.g. II3)
Involvement of lymph node regions or structures on both sides of the diaphragm
With or without involvement of splenic, hilar, coeliac or portal nodes
With involvement of para-aortic, iliac and mesenteric nodes
Involvement of one or more extranodal sites in addition to a site for which the designation "E" has been used (see below)
Designations applicable to any disease stage
Fever (temperature >38°C), drenching night sweats, unexplained loss of > 10% of body weight within the preceding 6 months
Bulky disease (a widening of the mediastinum by more than one third, or the presence of a nodal mass with a maximum dimension greater than 10 cm)
Involvement of a single extranodal site that is contiguous or proximal to the known nodal site
Pathological stage (as determined by laparotomy)
At initial presentation there is usually lymph node enlargement on either physical examination or the plain chest radiograph. The cervical nodes are the most frequently affected at initial presentation followed by the nodes of the groins. The enlarged nodes are firm and nontender on palpation. Systemic symptoms may include fever, night sweats, anorexia, fatigue, weight loss, pruritus or bone pain following alcohol intake. The presence of such systemic symptoms is classified by the modifier "B" in the staging system and are often associated with extensive intra-abdominal disease. HD spreads predictably from one lymph node group to the next contiguous group. Direct invasion from affected nodes into a visceral organ or musculoskeletal system is another characteristic form of spread. The majority of Hodgkin's patients have localized stage I or stage II disease at presentation. Long-term survival approximates 75% when only radiotherapy is used. Additional chemotherapy may reduce the rate of recurrence. Combination of both radiation therapy and chemotherapy is usually reserved for patients who have advanced stage disease or massive mediastinal involvement. Approximately 85% of patients have an intrathoracic involvement, the most common location in the chest being mediastinal and hilar lymph nodes.
Radiologically, the cardinal sign is a lymph node enlargement on chest radiography and CT scans which can be accompanied by pulmonary or pleural involvement. CT is usually required for the staging of patients with HD. Multiple nodes groups are commonly enlarged. The prevascular and paratracheal lymph nodes are the most commonly involved (Fig. 1). Other sites include hilar, subcarinal, paracardiac, internal mammary and posterior mediastinal nodes. Enlargement of a single node group can be seen in some patients, most commonly in the prevascular mediastinum. Direct extension of lymphoma from the mediastinum to the lung, the pleura or the chest wall is common with large mediastinal masses (see pulmonary lymphoma, pleural lymphoma) (Fig.2). Primary pulmonary HD is extremely uncommon. Enlarged lymph nodes are of homogeneous soft-tissue attenuation in the majority of cases on CT scans. They can be well-defined and discrete, or associated with diffuse mediastinal infiltration. Areas of low attenuation or necrosis following contrast enhancement are not uncommon for large nodal masses. Cystic and necrotic appearing enlarged lymph nodes may also be seen. Rarely, nodes show fine flecks of calcification, before any treatment. Involvement of the thymus is present in association with mediastinal lymph node enlargement in approximately 30% of cases (Fig.1).
Chest radiographs are usually used for monitoring patients in the months and years following treatment. CT is usually obtained 2-4 months following treatment to assess the completeness of response and to provide a baseline for subsequent studies in patients who develop radiographic abnormalities.
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Hodgkin's disease, Fig.1 (a)
Hodgkin's disease, Fig.1 (b)
Hodgkin's disease, Fig.2
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