1/78. Pseudo-myasthenia gravis and thymic hyperplasia in Graves' disease. BACKGROUND: Diagnostic confusion between thyroid disease and myasthenia gravis (MG) can arise because the two may have similar clinical features, and also because of the more frequent coexistence of these autoimmune disorders in the same individual. In MG, autoantibodies directed against the acetylcholine receptor result in muscle weakness. Thymic pathology is well recognized in MG, with thymic hyperplasia frequent in early onset MG and thymoma more common in later onset MG. In Graves' disease, autoantibodies against thyroid antigens result in hyperthyroidism. A seldom-recognized feature of Grave's disease is the occurrence of an enlarged thymus (thymic hyperplasia) on chest CT, or of thymic lymphoid hyperplasia pathologically. CASE STUDY: This report describes a case in which the discovery of a mediastinal mass during imaging of the thyroid, and the presence of myasthenic-like symptoms, in a patient with Graves' disease prompted investigations into whether the patient also had MG. RESULTS: Despite symptoms which strongly suggested MG, subsequent investigations did not confirm the diagnosis, and treatment of Grave's lead to a resolution of the symptoms and regression of the thymic enlargement seen on CT. CONCLUSIONS: The case study highlighted clinical similarities between Grave's disease and myasthenia gravis which might cause diagnostic confusion, and also the investigations which are useful in order to differentiate the two diseases. In addition to common clinical features, the autoimmune diseases Grave's disease and myasthenia gravis may both produce radiological thymic enlargement. ( info) |
2/78. Recurrent massive hyperplasia of the thymus. Differentiation of massive thymic hyperplasia from malignant lesions requires early resection. We report a case in which thoracoscopic thymectomy was performed for massive hyperplasia recurring 16 years after steroid therapy. This case provides additional information on the natural history, surgical management and histology of the disease. ( info) |
3/78. Massive true thymic hyperplasia. A case of massive true thymic hyperplasia in a child of eleven months is described. This rare disorder must be included in the differential diagnosis of a mediastinal mass in children. diagnosis and management are discussed and the relevant literature is reviewed. ( info) |
4/78. Rebound thymic hyperplasia after chemotherapy in a patient treated for pulmonary metastases. A 38-year-old patient presented with an anterior mediastinal mass after chemotherapeutic and surgical treatment for lung metastases from a malignant histiocytoma. Because of the risk for tumour recurrence the thymic mass was resected. Thymic hyperplasia was found on pathological examination. In this case thymic hyperplasia is a rebound phenomenon aflcer chemotherapy. It appears to atrophy during the administration of chemotherapy and regrow afterwards. Surgical resection provides the definitive diagnosis and treatment. ( info) |
5/78. Respiratory distress in a neonate with an enlarged thymus. Thymic hyperplasia, although not a rare condition in infancy, is usually asymptomatic. We describe an infant presenting in the perinatal period with marked tachypnoea. An enlarged thymus, demonstrated on chest radiograph and CT, was associated with small-volume, non-compliant lungs. Other causes of pulmonary malfunction and maldevelopment were excluded. CONCLUSION: Thymic enlargement is unusually associated with neonatal respiratory distress but should be considered in the differential diagnosis. ( info) |
6/78. Cytologic diagnosis of true thymic hyperplasia by combined radiologic imaging and aspiration cytology: a case report including flow cytometric analysis. True thymic hyperplasia (TH) is an age-dependent increase in size and weight of the thymus gland, which by definition maintains a normal histologic architecture. TH can mimic other important diseases, including lymphofollicular hyperplasia, thymoma, lymphoma, and germ-cell tumors. Traditionally, separating these entities has required a formal surgical biopsy. Given that many of these conditions occur in children, this can be a traumatic experience for both the patient and family members. Fine-needle aspiration biopsy has the distinct advantage of being able to obtain diagnostic material without requiring general anesthesia. We are aware of only one previously reported case of an enlarged thymus being subjected to aspiration cytology. We therefore present a case of thymic hyperplasia in a 5-mo-old child diagnosed by combined radiologic and cytologic parameters, including flow cytometric analysis. ( info) |
7/78. Thymic hyperplasia as a source of ectopic ACTH production. A 26 year-old man with suspected Cushing's disease underwent transsphenoidal exploration of the pituitary without any evidence of microadenoma or hyperplasia. Progressive hypercortisolism necessitated bilateral adrenalectomy. Postoperatively, skin pigmentation gradually developed with a marked elevation of plasma ACTH levels, and CT scanning uncovered a thymic mass. Following removal of the thymic mass, skin pigmentation disappeared and plasma ACTH levels fell to normal. The excised mass was found to be a benign thymic hyperplasia without epithelial or carcinoid tumor cells. However, gel chromatography showed that the thymic tissue extract contained high ACTH content comparable to that of ectopic ACTH-producing tumors with a major component corresponding to ACTH(1-39). Northern blot analysis and in situ hybridization revealed the expression of proopiomelanocortin transcripts in lymphocytes of thymic hyperplasia. This report suggests that lymphocytes in thymic hyperplasia are the most likely site of deregulated ACTH expression causing ectopic ACTH syndrome. ( info) |
8/78. Malignant lymphoma of the thyroid following irradiation. A case of primary lymphocytic lymphoma of the thyroid is presented occurring in a 19-year-old woman. The young age of this patient, as well as the possibility of thymic radiation therapy as an infant, being a predisposing factor makes this case unique. The association with Hashimoto's thyroiditis has been previously reported. ( info) |
| We report a case of non-Hodgkin's lymphoma of Burkitt's type with thyrotoxicosis and thymic hyperplasia in a 27-year old man. As far as we are aware this is the first reported case of Burkitt's lymphoma, thymic hyperplasia and thyrotoxicosis occurring in the same patient. ( info) |
10/78. Airway compression following thymus hyperplasia in an infant with Pierre Robin sequence and congenital diaphragmatic hernia. A female infant with respiratory embarrassment due to external compression of the tracheobronchial tree by the thymus is presented. After successful intrauterine drainage of pleural effusions, she was born with a diaphragmatic hernia and Pierre Robin sequence, which required long-term mechanical ventilation and several surgical interventions, including tracheostomy, until she breathed spontaneously. At age 7 months, she was rehospitalized in respiratory failure because of pneumonia. At this time, thymus hyperplasia was first diagnosed, which had caused tracheobronchomalacia and displacement of the tracheobronchial tree. weaning from the ventilator was unsuccessful for 8 weeks. She underwent thymectomy, following which impairment of breathing resolved immediately. Different manifestations of thymus enlargement and their relation to impaired breathing are discussed. ( info) |