Combined effect of thymectomy on myasthenia gravis in patients with concomitant auto-immune diseases: a 22-year single-center experience

Myasthenia gravis (MG) is an autoimmune disease (AD), and patients with MG often have other types of ADs. We analyzed the prognosis of patients with MG complicated by AD after thymectomy. A retrospective analysis was performed for patients with MG complicated by ADs treated surgically in our center over the past 22 years, and their general condition and follow-up data were collected and analyzed. 33 patients were included totally. 28 patients displayed improvement or even complete recovery of MG, and 23 of 36 ADs revealed improvement or even complete recovery. The prognosis of MG is significantly correlated with the duration of postoperative follow-up time (p = 0.028), and in patients with thymoma, the larger the tumor diameter, the better the prognosis of MG (p = 0.026). Thymic hyperplasia patients were predominantly female (p = 0.049) and young (p < 0.001). The most common concomitant AD in this study was a thyroid-associated AD, which was associated with thymic hyperplasia (p < 0.001), Osserman type I MG (p < 0.001), and young age (p < 0.001). Thymectomy had a good therapeutic effect on MG complicated by AD, and there was a close correlation between surgery, thymus, MG, and ADs.

Modified unilateral video-assisted thoracoscopic extended thymectomy for myasthenia gravis using 5-mm incisions: A case report

RATIONALE

Myasthenia gravis (MG) is the most common cause of acquired neuromuscular junction disorder. Thymectomy has been established as an effective therapy for MG, as it attenuates the natural course of the disease and may result in complete remission.

PATIENT CONCERNS

We report the case of a 22-year-old female with a 6-year history of MG presented with bilateral ptosis, diplopia, and intermittent dysphagia. She denied shortness of breath, dysarthria, and fatigue.

DIAGNOSES

She had been diagnosed with MG 6 years previously at the Neurology Department of our hospital. A computed tomography (CT) scan revealed thymic hyperplasia INTERVENTIONS:: She was treated with modified unilateral VATET that minimized incision size.

OUTCOMES

Unilateral VATET was performed using two 5-mm incisions to minimize pressure on intercostal soft tissues/nerves and reduce postoperative pain.

LESSONS

The lesson learnt from this case report is that this modified VATET method could be a useful approach to the management of non-thymomatous MG. The ability to achieve complete dissection with good cosmetic results may lead to wider acceptance of this technique by patients with MG and their neurologists for earlier thymectomy and improved outcomes. Additional studies are needed to determine the superiority of this approach to established methods.

[An enlarged thymus associated with Graves' disease]

BACKGROUND

Thyrotoxicosis and orbitopathy are the best-known expressions of Graves' disease. There are also rarer and less-known phenomena, such as thymic hyperplasia. Identification of these is important in order to avoid potentially unnecessary invasive interventions.

CASE DESCRIPTION

In the case of two young women with lung embolisms, CT pulmonary angiography also revealed an enlarged thymus. This turned out to be caused by as of yet unknown Graves' disease. Since pathological examination of a thymus-biopsy sample was unable to rule out thymoma, thymectomy was performed on the first patient. Pathological examination of the entire thymus revealed hyperplasia. Additional FDG-PET/CT scan of the second patient revealed diffuse hyperactivity in the diffusely enlarged thymus. In this case, we opted for expectant treatment. A follow-up FDG-PET/CT scan 1 year later, revealed a non-abnormal thymus.

CONCLUSION

An enlarged thymus caused by thymic hyperplasia is a less well-known manifestation of Graves' disease. In case additional abnormalities develop in patients with Graves' disease, it is important to consider that these might be related to the disease before diagnosing an additional new condition.

[VATS THYMECTOMY IN MYASTHENIA GRAVIS TREATMENT--A CASE REPORT]

Myasthenia gravis (MG) is a chronic autoimmune disease characterized by weakness of skeletal muscles, specifically ocular. Relationship between the thymus gland and MG is not fully understood yet. Thymectomy is recommended for individuals with thymoma, but should be considered in all patients under 60 years of age with generalized MG in cases with no thymomatous tissue. We report a 27-year-old female patient with ocular type myasthenia gravis and radiological findings of anterior mediastinal mass, treated by VATS thymectomy. The intervention was carried out by 3-portal right-sided thoracoscopic approach. Single-lung ventilation and carbon-dioxide insufflation provided working space, and harmonic scalpel was used for the dissection and ligation. The patient's postoperative course was uncomplicated and the patient was discharged on the third postoperative day. The aim of our case report is to stress the importance of VATS technique in faster recovery and better cosmetic effect than in sternotomy procedures.

[Thymectomy and antibodies to acetylcholine receptors (AChR) in patients with myasthenia gravis in the early postoperative period]

Thymectomy and removal of the hyperplastic thymus have been performed in 21 patients with myasthenia. In 14 patients, thymectomy is performed through thoracoscopic access (TA), while in 7 cases through thoracotomic access (TT). The serum levels of antibodies to acetylcholine receptors (AChR) determined before and after surgery were increased in both groups of patients. Thus, thymectomy, regardless of the degree of clinical improvement in early post operative period, significantly increases the level of anti-AChR antibodies in the serum of patients in the early postoperative period compared to baseline. These changes may reflect the immune response to a stressful situation related to the traumatic surgery. It should be noted that the level of anti-AChR antibodies was significantly higher in a group of TT that may be related with a larger volume of the removed tissue.

Clinical features, diagnostic approach, and therapeutic outcome in myasthenia gravis patients with thymectomy

PURPOSE

Thymectomy has been widely employed in the treatment of myasthenia gravis (MG). However, little data exist in Iran demonstrating the efficacy and morbidity of thymectomy. The aim of this study was to determine the clinical features, diagnostic approach, and therapeutic outcome in patients with MG who underwent thymectomy.

METHODS

This historical cohort study was conducted in 3 university hospitals in Tehran. Preoperative and operative indices of 61 patients with MG who had been treated with thymectomy in these hospitals from September 2000 to July 2005 were reviewed. Among them, 20 patients were followed during one year after operation for determination of postoperative complications and one year mortality rate.

RESULTS

The most common manifestations of MG were ptosis (77.0%) and upper limbs weakness (70.4%). CT scans of the thymus showed thymus enlargement, thymoma and thymus hyperplasia in 51.5% (22/43), 11.6% (5/43) and 2.32% (1/43) of patients, respectively. The postoperative complications were found in 13.1% of patients and one year mortality rate of thymectomy was 6.6%.

CONCLUSION

Regarding to high one year mortality rate of thymectomy in patients of MG in this study, the assessment of the factors related to the mortality and outcome of patients who underwent thymectomy in Iran are necessary.

[Myasthenia gravis]

Myasthenia gravis is a rare, auto-immune neuromuscular junction disorder. Prevalence rates is about 50/1,000000. The disease results from circulating auto-antibody attacks against post-synaptic targets (acetylcholine receptor [AChR] in 80% cases) on the endplate region of the postsynaptic membrane. The diagnosis is supported clinically by transient weakness, increased by activity that can affect eye movements, swallowing, speech, upper and lower limbs, and trunk. There are generalized or focalized forms (as ocular myasthenia). The course is variable and evolved either with attacks or more chronically. Helpful tests for diagnosis are serologic antibodies detection against AChR, decrement of muscle action potential after repetitive nerve stimulations, identification of thymus gland abnormality (frequently associated with myasthenia) by chest computed tomography. Myasthenia gravis treatment is based on oral form of cholinesterase inhibitors, corticosteroids and other immunosuppressive drugs in severe forms. During myasthenia crisis, intraveinous immune globulines or plasma exchanges can be used. Thymectomy is proposed in case of thymus abnormality.

Gigantic enlargement of the thymus gland

True massive thymic hyperplasia is a very rare entity, characterized by an increase in the size and weight of the thymus gland, without an apparent cause. Surgery has been required in patients with severe respiratory distress. We present an idiopathic true massive thymic hyperplasia in a 5-month-old boy.

Antigen-specific T-cell activation in hyperplastic thymus in myasthenia gravis

In order to determine whether antigen-specific T-cell activation by dendritic cells (DCs) is accelerated in thymuses exhibiting lymphofollicular hyperplasia (TLFH) among patients with early-onset myasthenia gravis (EOMG), we investigated the expression levels of phosphorylated protein kinase C (PKC)theta and the local relationship between the presence of phosphorylated PKCtheta and the homing receptor CD44 or CD83, a marker for mature DCs, in samples taken from EOMG patients with early improvement following thymectomy, in remnant thymuses from late-onset MG patients, and in non-MG control thymuses. Antigen-specific T-cell activation was markedly accelerated in TLFH from EOMG patients. Activated T cells and adjacent DCs appeared to be components of a CD44(high) cell population circulating from the blood to the thymus. Although there is no convincing evidence that thymectomy is of benefit in MG, in some EOMG patients with early improvement following thymectomy, blockade of CD44-associated circulation mechanisms is probably the cause for the early benefits of thymectomy and is a potential alternative to thymectomy.

Myasthenia gravis and scleroderma: Two cases and a review of the literature

Myasthenia gravis is uncommon in patients with scleroderma, and when diagnosed is usually associated with previous use of d-penicillamine. Clinically, both myasthenia and scleroderma may present with fatigue, weakness and bulbar symptoms, so one of diagnoses may be delayed. We report two new cases and review clinical features of 12 other reported cases of co-existing scleroderma and myasthenia gravis, unrelated to previous d-penicillamine therapy. Co-occurrence of myasthenia and scleroderma was reported almost exclusively (13/14) in women with a mean latency of 7.03 years. Most patients (10/11) had seropositive generalized myasthenia, and there were no cases with exclusively ocular symptoms. Three patients with pre-existing myasthenia were safely treated with d-penicillamine. Myasthenia and scleroderma occur in the context of an underlying autoimmune diathesis, but their co-occurrence could be underreported as the recognition of either disorder may be delayed by overlapping clinical symptoms. Our findings also suggest that d-penicillamine may be cautiously used in selected patients with pre-existing scleroderma and myasthenia, when potential benefits outweigh the risk of possible myasthenia exacerbation.

A combination of total intravenous anesthesia and thoracic epidural for thymectomy in juvenile myasthenia gravis

Juvenile myasthenia gravis is the acquired form of the disease in children and presents with ocular signs, fatigability, weakness and bulbar problems. The majority of patients demonstrate thymic hyperplasia and have been shown to benefit from thymectomy. The main considerations for the anesthesiologist are the degree of muscle weakness, the muscle groups involved and sensitivity to neuromuscular blocking drugs and volatile agents. Total intravenous anesthesia (TIVA) with epidural analgesia is probably the anesthetic technique of choice, although the latter is often avoided, because of the risk of a very high block. Two cases of thymectomy are presented where anesthesia was provided using a combination of TIVA and thoracic epidural analgesia. Both patients tolerated the technique well and had an uncomplicated perioperative course.

The distribution of parenchyma, follicles, and lymphocyte subsets in thymus of patients with myasthenia gravis, with special reference to remission after thymectomy

OBJECTIVE

We sought to examine the distribution of parenchyma, follicles, and lymphocyte subsets in the thymus of patients with myasthenia gravis and to identify determinants of remission after thymectomy.

METHODS

Sixty patients with myasthenia gravis who underwent thymectomy were examined. The thymus was divided into upper, middle, and lower parts. The upper part was defined as the superior horn, the lower part as the inferior horn, and the middle part as tissue located between the 2 horns. The percentage of parenchyma was measured morphometrically. The degree of follicular hyperplasia was classified into 5 grades. The densities of CD3+, CD4+, and CD8+ lymphocytes were classified into 5 grades. The remission of myasthenia gravis after thymectomy was examined with those variables in each part of the thymus.

RESULTS

The middle part had the highest percentage of parenchyma, the highest grade of follicular hyperplasia, and the highest density of CD3+, CD4+, and CD8+ lymphocytes among the 3 parts (P < .001-.05). The grades of follicular hyperplasia in the middle and lower parts were significantly higher in patients with improvement of myasthenia gravis than in those without (P < .05). The densities of CD3+, CD4+, and CD8+ lymphocytes in the cortex of the middle part were significantly higher in patients with improvement than in those without improvement (P < .01-.05).

CONCLUSIONS

The thymus has a heterogeneous distribution of parenchyma, follicles, and lymphocyte subsets. The middle part had the largest parenchyma, the highest grade of follicular hyperplasia, and the highest densities of CD3+, CD4+, and CD8+ lymphocytes among the 3 parts of the thymus. The grade of follicular hyperplasia and the density of these lymphocyte subsets are predictive of improvement in myasthenia gravis after thymectomy.

Eile mit Weile

Ein 36-jähriger Portugiese wurde wegen eines diffusen Krankheitsgefühls, eines Gewichtsverlusts von 25 kg im letzten halben Jahr sowie wegen Nachtschweißes auf Zuweisung eines Hausarztes bei uns im Spital abgeklärt. Im CT des Thorax und Abdomens fand sich nebst einer bis nach retrosternal reichenden Struma eine Raumforderung im vorderen oberen Mediastinum. Gleichzeitig wurde die Diagnose einer Hyperthyreose vom Typ eines Morbus Basedow gestellt. Diese wurde mittels Carbimazol thyreostatisch behandelt. Aufgrund der unklaren Dignität wurde die Raumforderung im vorderen oberen Mediastinum thorakoskopisch entfernt. Histologisch handelte es sich um eine Thymushyperplasie mit Begleitthymitis ohne Zeichen der Malignität. Die Assoziation von Morbus Basedow und Thymushyperplasie ist in der Literatur beschrieben, bei Internisten und auch Endokrinologen jedoch wenig bekannt. Die Thymushyperplasie ist unter thyreostatischer Therapie regredient. Rückblickend hätten wir bei unserem Patienten auf die Thymektomie verzichten sollen.

Unusual Remnant Thymic Tissue in an Adult Mimicking Malignant Neoplasm: Escape From Age-Related Involution

Here we report on a 55-year-old man with an abnormal anterior mediastinal shadow and multiple nodules in the thymus, which increased in size over a period of 15 months. He was diagnosed with early prostatic cancer, and treated with chemotherapy. Although no definite preoperative diagnosis was obtained, surgery was performed because of the possibility of malignant neoplasm or metastasis. Extended thymectomy was performed and pathological examination revealed that the nodules were remnant thymic tissue and not malignant lesions. Although the cause of this unusual remnant thymic tissue remains unclear, it may have been related to autoimmune or endocrinological disease.

[Is pure red cell aplasia a new extra digestive manifestation of celiac disease?]

INTRODUCTION

Celiac disease is an autoimmune enteropathy that appears on a predisposed genetic background. Its clinical presentation has been extended those last years by varied extradigestive manifestations.

EXEGESIS

This is a case report of a twenty-year-old woman who presented simultaneously a celiac disease and pure red cell aplasia. The IgA and IgG antigliadin antibodies as well as antinuclear, anti-DNA, anti-SSA and anti-SSB antibodies were detected, without any clinical symptom supporting the diagnosis of systemic lupus erythematosus or Sjögren syndrome. Thoracic CT-scan reveals a thymus enlargement and biopsy concludes to thymus hyperplasia at histological examination. Pure red cell aplasia regressed after gluten-free diet, corticoid therapy and thymectomy.

CONCLUSION

This observation, added to the three others paediatric cases previously published in the literature concern an uncommon association between pure red cell aplasia and celiac disease. However, they are not enough to conclude to a direct link between these two disorders. Pure red cell aplasia could represent un new dysimmune manifestation occurring in celiac disease, but this will need to be confirmed with others cases.

Multilocular thymic cyst associated with follicular hyperplasia: clinicopathologic study of 4 resected cases

We report here 4 cases of multilocular thymic cysts (MTCs) with reactive lymphoid follicular hyperplasia. They were admitted to our hospital to examine anterior mediastinal masses demonstrated on chest computed tomographic scans. Three patients presented high-grade intermittent fever, and 2 patients were associated with Sjogren syndrome with elevated serum antinuclear antibody levels. All patients were subjected to extended thymectomy. Interestingly, their fever disappeared immediately after surgery. Histologically, the lesions were characterized by several cystic spaces separated by various thick walls with dense lymphoid tissue containing large reactive germinal centers. The inner cyst walls were lined by flattened cuboidal epithelia in some portions. Columnar epithelia with focal cilia were partially observed in 2 cases. These pathological findings led to a diagnosis of MTCs that were thought to result from cystic transformation of medullary duct derivatives by acquired inflammatory processes. The pathological findings, together with clinical courses of our cases, suggest that inflammation accompanied by autoimmune diseases may play, in part, an important role in the development of MTCs.

[Activity of the thyroid and sex hormones in patients with myasthenia after surgical intervention]

In 1995-2003 yrs there were operated on 55 women for various forms of myasthenia. In 20 of them myasthenia coexisted with thymoma, in 35--have been combined with the thymus hyperplasia. In all the patients the hormonal misbalance was revealed, depending on changes in the thymus structure present.

Response of thymectomy: clinical and pathological characteristics among seronegative and seropositive myasthenia gravis patients

OBJECTIVE

To identify the response to thymectomy in patients with seronegative and seropositive myasthenia gravis (SPMG). We analyzed the associated diseases, thymus histology, and the severity of symptoms between the two groups. MATERIAL AND METHODS - DESIGN: Descriptive, comparative.

STUDY UNITS

Fourteen patients with seronegative myasthenia gravis (SNMG) and 57 patients with SPMG who had a thymectomy between 1987 and 1997, with at least 3 years of follow-up. The patients were divided into four groups; (1) Remission, (2) Improvement, (3) No change and (4) Deterioration.

RESULTS

Fourteen patients (20%) were seronegative and 57 were seropositive (80%). In the group of patients with SNMG, three patients were in remission (21%), five with improvement (36%), five with no change (36%) and one with worsening (7%). In the group of patients with SPMG, 12 were in remission (21%), 17 with improvement (30%), 25 with no change (44%) and three (5%) with worsening. The patients with SNMG were older, with less associated diseases and with a lower frequency of thymomas.

CONCLUSIONS

The response to thymectomy was similar between the two groups. It has been suggested that seronegative patients have a better prognosis, but our results show no differences.

Massive benign thymic hyperplasia in a six-month-old girl: case report

A 6-month-old girl presented with respiratory symptoms with a large right-sided mediastinal mass noted on diagnostic imaging. Percutaneous biopsy revealed normal thymic tissue. Steroids were administered with no response. Right thoracotomy and complete thymectomy were performed. The specimen weighed approximately eight to ten times normal weight, and histology and flow cytometry revealed normal thymic tissue consistent with benign hyperplasia. The child has remained tumor free for a year since surgery. The rare nature of this tumor leads us to report this case and review the current literature.

[Factors which may influence the surgical outcome in myasthenia gravis]

OBJECTIVE

This study intends to assess the factors which may influence the surgical outcome in myasthenia gravis.

METHOD

52 myasthenic patients were operated on in the IIIrd surgical unit, Iaşi, undergoing extended thymectomy through a complete longitudinal sternotomy during a period of 21 years (1980-2001), the surgical outcome being variable. The following factors: age, clinical stage (Osserman classification), the history length and the histopathology of the specimen were analysed in respect with the surgical outcome which varied from complete remission and clinical improvement till no effect and death. Out of 52 patients, 28 were under the age of 30 years and 24 above 30 years of age. 5 patients were operated on in the first clinical stage, 34 in the second clinical stage, 10 in the third stage and 3 in the fourth. 21 patients had had under 1 year history of the disease, 11 patients under 2 years and 20 patients over 2 years. 40 cases presented non-tumoral pathology of the thymus gland and 12 cases presented thymomas.

RESULTS

The best surgical results were recorded in patients under 30 years of age, operated in the first and second clinical stage, with a history under 1 year and non-tumoral pathology of the thymus.

CONCLUSION

Myasthenia gravis is the only one acquired autoimmune disease in which surgical treatment offers the chance of complete remission if the following criteria are encountered: young patient, short history, initial clinical stage and non-tumoral pathology.

The thymus. Pediatric surgical aspects

Since the original description of thymic death in an infant 400 years ago, the thymus has been recognized as an important structure to practitioners caring for infants and children. The source of many cysts, masses, and tumors in the neck and mediastinum, the thymus gland merits the pediatric surgeon's attention. The thymus is clearly an important lymphoid organ, the removal of which may be therapeutic in MG, but congenital absence leads to profound cell-mediated immunodeficiency. The immunologic sequelae of its neonatal extirpation remains obscure. It is apparent that further research is needed to clarify the functional role of the thymus gland in the developing immune system. Until better elucidated, a conservative approach to neonatal thymectomy may be justified.

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.

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.

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.

Early and late results after thymectomy in myasthenia gravis: a retrospective study [correction of analysis]

BACKGROUND

This study aims to evaluate the early and late outcome of patients treated by surgery for myasthenia gravis and the diagnostic value of the Besinger Score, which is based on a correlation of severity of symptoms with specific antibodies to acetylcholine receptors, in the follow-up investigation after surgical therapy.

METHODS

Between June 1984 and April 1992 thoracotomy was performed in 51 myasthenia gravis cases at our department. The retrospective analysis considered patients with (n = 13) or without thymoma (n = 38). The Besinger score was used to describe the severity of disease preoperatively and up to 5 years postoperatively.

RESULTS

The Besinger score fell continually post surgery. Changes in relative serum concentrations of antibodies were similar to the Besinger score. Five years after thymectomy complete remission was diagnosed in 40% of the patients. The required dosage of pyridostigmine had fallen by two thirds after 5 years. Patients with follicular hyperplasia had significantly higher remission rates than those with thymoma.

CONCLUSIONS

Surgery for myasthenia gravis is successful. The Besinger score well quantifies the severity of the disease.

[Hypophyseal-adreno-gonadal system function in myasthenia patients with tumorous and nontumorous pathology of the thymus]

Overall twenty-five patients (all women) who ranged from 16 to 56 years old were examined. They were divided into two groups: group I was formed of subjects with hyperplasia of the thymus gland, group II--thymoma. Blood serum levels of prolactin, progesterone, estriol, estradiol, testosterone hydrocortisone. All patients showed a significant increase in average blood plasma levels of estrogens, testosterone and prolactin. Average levels of progesterone and hydrocortisone in patients with thymus hypertrophy were lower than in controls, while in thymoma patients these were much higher. The data submitted are indicative of substantial differences in the endocrine status of myasthenia patients depending on tumor or nontumor lesion of the thymus gland, which fact may suggest different pathogenetic mechanisms of development of the condition.

Thymectomy in black children with juvenile myasthenia gravis

Fifteen black children with juvenile myasthenia gravis presented to our institution over a 10-year period at ages ranging from 18 months to 7 years, 4 males and 11 females. Twelve presented with progressive, generalised weakness and 3 had bulbar manifestations. Ocular signs were absent in 2 patients. All 15 patients were placed on pyridostigmine bromide (Mestinon) and 1 also required steroids and plasmapheresis. Medical therapy only was instituted in 5 patients, of whom 2 came to surgery, 2 died, and 1 was lost to follow-up. Thymectomy was performed in 12 children (including the 2 with failed medical therapy) via a median sternotomy with no mortality or morbidity related to the operation. The timing of surgery was less than 3 months in 75% of the children. Thymic hyperplasia was noted in 10 glands and 2 were reported as normal. Of the children in the operative group, 83% are on minimal medication or in total remission. Better results were noted in young patients with early thymectomy and diseased glands.

Hyperplasia of thymic gland

Hyperplasia of the thymus is the most common anterior mediastinal mass in infants. It is however exceedingly difficult to evaluate by the weight of the gland as it continues to grow after birth until puberty and thereafter undergoes progressive atrophy. It normally maintains most of the radiographic characteristics of the normal thymus. Massive thymic hyperplasia, a rare variant of true thymic hyperplasia is extremely rare during the first two decades of life and clinically can cause mediastinal compression or acute and recurrent pulmonary infection. Two such cases are reported and the clinico-pathology is briefly described and discussed.

Detection and morphology of thymic remnants after video-assisted thoracoscopic extended thymectomy (VATET) in patients with myasthenia gravis

Thymectomy is often an extremely useful therapeutic procedure in myasthenia gravis (MG) and is usually indicated for adult patients with generalized disease. Because remnants of thymus may remain in extrathymic fat, an extended thymectomy is recommended. A new surgical approach without sternotomy: video-assisted thoracoscopic extended thymectomy (VATET) was performed in 30 MG patients. The weight of removed thymus ranged from 10.8 to 113 grams. The weight of fatty tissue removed from pretracheal, anterior mediastinal and costophrenic areas ranged from 6.3 to 74.8 grams. Histological examination revealed thymic remnants in 14.8% of pretracheal fat samples and in 33.3% of samples from anterior mediastinal plus costophrenic areas. These findings indicate that VATET is a radical procedure and may be the first choice surgery for young female MG patients, since aesthetic sequelae are reduced compared to procedures involving sternotomy.

[Imaging of the thymus gland in myasthenia gravis (computerized tomography and magnetic resonance)]

Since thymectomy is nearly always indicated as a possible treatment of myasthenia gravis, we examined with Magnetic Resonance (MRI) and Computed Tomography (CT) 22 patients (21-62 years old) to identify the best methodological approach. MR images were obtained with a 1.5 T superconducting unit with slice thickness ranging from 6 to 8 mm and an interslice gap of 0.6 and 0.8 mm. Spin-echo images were acquired with repetition time (TR) < 700 ms and echo time (TE) of 20 ms and T2-weighted images with TR > 1800 ms and TE of 80 ms. The sections were obtained, with cardiac gating, on transverse and sagittal planes. CT was performed with contiguous 5-mm slice thickness, after intravenous bolus injection of contrast medium. All the patients underwent surgery of anterior mediastinum and histologic diagnosis was made. Both CT and MRI correctly identified the patterns of normal thymus or hyperplasia not associated with gland enlargement, the only two cases of hyperplasia with thymic enlargement and clearly demonstrated thymomas. MRI appears to be more accurate in the evaluation of the relationship between thymus and contiguous structures. If pericardial infiltration is suspected, sagittal MR scans yield accurate information on tumor spread. We recommend MRI of anterior mediastinum to rule out the presence of a thymoma and the possible involvement of contiguous structures.

[Thymic lymphoid hyperplasia of myasthenia gravis patients: correlation with clinical features and efficacy of thymectomy]

Thirty nine thymus tissues from myasthenia gravis patients without thymoma who underwent extended thymectomy were evaluated on thymic lymphoid hyperplasia with special emphasis on clinical features and the efficacy of thymectomy. Of 39 patients, 31 were women, but 3 of 7 patients without thymic lymphoid hyperplasia were men. The hyperplastic index of the thymus correlated largely with serum anti-Ach-R antibody titers before surgery. Age, myasthenic type and preoperative duration of the symptoms were almost unrelated to the hyperplastic change in the thymus. The effect of thymectomy was more remarkable in the patients with the hyperplastic thymus than that in them without it, who obtained still no remission after surgery, although the remission rate of them with it reached to 25%. Of 7 patients without the hyperplastic thymus, 4 had no detectable antibody to acetylcholine receptor, whereas in 32 patients with it only 2 were seronegative. This negative immunological factor might make adverse response to thymectomy. Although unfavorable response to thymectomy were observed in the patients without the hyperplastic thymus, most of them were significantly improved through a supplementary treatment with steroid after surgery. Thymectomy was a favorable treatment for myasthenia gravis patients with thymic lymphoid hyperplasia, whereas in them without it the result of thymectomy was unsatisfactory.

Maximal thymectomy for myasthenia gravis

Maximal thymectomy was carried out in 48 patients with myasthenia gravis (MG). There were 18 males and 30 females. Thymic hyperplasia was found in 38, and atrophic thymus in 8, patients. Two patients had thymoma. In the non-thymomatous myasthenia gravis complete remission was achieved in 16 patients (34.8%) and pharmacological remission in 20 patients (43.5%) thus giving a total remission in 36 (78.3%) patients. Six patients (13%) improved. There was no improvement in four patients. Thus, the overall benefit from thymectomy was 91.4% in this series. We found that sex, age at onset of disease and steroid therapy influenced the outcome of thymectomy. On the other hand, duration of disease, anti-acetylcholine receptor (AntiAchR) antibodies and thymic histology did not have any bearing on the complete remission rate.

[Paraneoplastic Cushing's syndrome. Pseudotumors of the thymus occurring after correction of hypercorticism. 3 cases]

Ectopic ACTH-secreting tumours responsible for paraneoplastic Cushing's syndrome are invisible at radiography in about 50 percent of the cases. In this situation, the current attitude is to correct the hypercorticism and then embark on a regular morphological monitoring in search of the initial tumour with the purpose of removing it. We report the cases of 3 patients who had a paraneoplastic Cushing's syndrome of unknown origin in 1 case and consecutive, in 2 cases, to a bronchial carcinoid tumour initially occult and discovered 30 and 42 months respectively after the onset of the disease. Six to 10 months after hypercorticism was cured with ketoconazole and bilateral adrenalectomy, a thymic mass 2 to 5 cm in length was detected by computerized tomography or magnetic resonance imaging in all 3 patients. At resection of the thymus, performed in 2 cases, a benign hyperplasia of this organ with negative immunohistostaining for ACTH was discovered. This abnormality, seldom reported, seems to result from the abrupt cessation of hypercorticism. It must be known to avoid an unnecessary thymectomy during supervision of patients with paraneoplastic Cushing's syndrome related to a radiologically occult tumour.

Rebound thymic hyperplasia following high dose chemotherapy and allogeneic BMT

We describe a child with acute lymphoblastic leukemia who showed mediastinal widening 8 months after allogeneic BMT. Total thymectomy was carried out by the transcervical approach. Histologic examination showed only thymic hyperplasia. The immunohistologic investigation revealed a normal distribution of thymic cell elements, without evidence of clonal proliferation of lymphocytic subpopulations. This case supports the hypothesis that thymic hyperplasia following chemotherapy may be merely a rebound phenomenon. The patient had an uneventful postoperative recovery and remains in remission more than 1 year after BMT.

Thymectomy in myasthenia gravis. The Jamaican experience

Forty-five patients with myasthenia gravis (MG) were subjected to thymectomy by the median sternotomy technique and were followed up for 4,380 patient months. No operative deaths occurred and 93.3% of the patients benefited from surgery with 28.8% achieving remission. Forty patients (88.5%) showed improvement within one month, and 73% of those who achieved remission did so in the first 2 years. Outcome was not affected by thymic pathology except in one patient who had a thymoma removed. These results confirm the value of thymectomy in the management of MG patients with generalised disease and the efficacy of the simple median sternotomy procedure.

Thymic enlargement in children

The presence of an anterior mediastinal mass in an infant or child is a diagnostic and therapeutic challenge. Few papers in the literature specifically address subtypes of thymic tumors in the pediatric population and their treatment. Our purpose was to determine which children are at significant risk of having a malignant thymic tumor. Four children were younger than 18 months old. Of these, two (50%) had respiratory distress from tracheal compression although all four had benign tumors. Of the 14 older children, only two were symptomatic, both of these from myasthenia gravis rather than the size of the mass compressing surrounding structures. Four of the 14 masses (29%) were malignant although none of the four were symptomatic. Children with benign tumors lived significantly longer than those with malignant tumors. The significant incidence of malignancy in thymic tumors when the patient is 18 months or older necessitates surgical exploration with complete removal of the mass. Children younger than 18 months require close follow-up and a trial of corticosteroids. Surgery is necessary if the mass enlarges or becomes symptomatic.

[Indications for thymectomy]

An absolute indication for thymectomy exists in all cases with tumors of the thymus gland, however, preoperative differentiation between benign and malignant lesions is not always possible even with modern imaging methods. In extensive tumors of questionable operability preoperative transthoracic needle biopsy (guided by CAT-scan) is recommended. After establishing the histological diagnosis, preoperative radio- and/or chemotherapy can be considered. Certain immunological diseases are a relative indication for thymectomy. Its value is proven in myasthenia gravis, questionable however in ulcerative colitis and erythroblastopenia. Systemic lupus erythematosus is a contraindication.

Thymic rebound in an adult following chemotherapy for testicular cancer

Thymic hyperplasia is reported in a 27 year old man following combination chemotherapy for metastatic testicular cancer. The occurrence of this phenomenon is reviewed and the implications for management discussed.

Thymic hyperplasia masquerading as recurrent Hodgkin's disease: case report and review of the literature

While the appearance of a mediastinal mass in a patient in remission from Hodgkin's disease frequently indicates recurrence, a number of benign processes may present in a similar manner. Tissue confirmation of relapse should be obtained prior to initiating further chemotherapy to avoid the morbidity of unnecessary treatment. We present a case of thymic hyperplasia that developed in a patient previously treated for Hodgkin's disease. Thymic hyperplasia is a poorly understood, apparently benign process that may be confused with recurrent lymphoma. Total excision of such a mass is recommended to rule out coexistent malignancy.