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Hypogammaglobulinaemia associated with thymoma is known as Good's syndrome. Whilst most thymomas present as an anterior mediastinal mass they seldom occur within the lung parenchyma.
A woman aged 72 had for 10 years experienced recurrent chest infections and left-sided pleuritic chest pain. She was now breathless and had a temperature of 398C. On auscultation of the chest she had coarse bilateral inspiratory crackles and diminished breath sounds at the left base. A chest radiograph showed extensive shadowing in the lower half of the left hemithorax. Sputum culture yielded a heavy growth of Pseudomonas aeruginosa. Her white cell count was raised at 14.16109/L and C-reactive protein was 515 mg/L. Blood urea, electrolytes and liver function tests were normal. Serum immunoglobulin concentrations were low with IgG 1.2 g/L (normal 7–16), IgA 0.47 g/L (0.7–4) and IgM 50.05 g/L (0.4–2.3). Thoracic CT revealed a 12.8 cm mass in the left lower lobe with associated pleural effusion (Figure 1a). There was no evidence of an anterior mediastinal mass. A needle biopsy of the mass showed typical mixed cortical and medullary pattern thymoma. It was felt that the immune deficiencies identified were sufficient to explain her clinical condition, so more complex tests of immune status, such as B cell response to protein (tetanus) and polysaccharide (pneumococcal polysaccharide) antigens, were not performed; nor did we assess antibody responses to test immunizations.
The patient was treated with intravenous antibiotics and started on immunoglobulin replacement therapy. Surgical resection of the thymoma was considered but her general condition and lung function were poor. She was therefore offered a course of radiotherapy and received 2000 cGy in five daily fractions. Repeat CT eight weeks later showed that the tumour had halved in volume and was more liquid in consistency (Figure 1b).
Thymomas, which have an incidence of 0.15 per 100 000,1 can be associated with various clinical syndromes including myasthenia gravis, red cell aplasia, pancytopenia, collagen vascular disease and endocrinopathies.2 The parathymic syndrome of hypogammaglobulinaemia known as Good's syndrome2 is characterized by susceptibility to infection by encapsulated bacteria, viruses and fungi; chronic bronchial sepsis is commonly a feature. In contrast to antibody deficiency disorders such as common variable immunodeficiency and X-linked agammaglobulinaemia Good's syndrome includes defective T-cell function—hence susceptibility to cytomegalovirus, herpes simplex, varicella zoster, HHV-8 and other virus infections. The proportion of thymomas associated with hypogammaglobulinaemia has been estimated as 6–11%.3,4 Because of the T-cell defect, the use of live vaccines in patients with Good's syndrome poses a significant risk. For example, a survey of complications associated with yellow fever immunization showed that 4 out of 23 vaccinees who developed vaccine-associated viscerotropic disease had an underlying thymoma (and, we presume, Good's syndrome).5 Most thymomas are slow growing with a tendency to recur locally; they seldom metastasize and can usually be cured by surgical resection.6 Primary intrapulmonary thymoma without an associated mediastinal component, as seen here, is exceptionally rare.7 These tumours arise from ectopic embryonic tissue. As far as we are aware, this is the first reported case of hypogammaglobulinaemia associated with such a tumour.