Recurrence of thymic hyperplasia after thymectomy in myasthenia gravis. Its importance as a cause of failure of surgical treatment

The impact of thymectomy in subgroups of Myasthenia gravis patients: a single center longitudinal observation

BACKGROUND

Myasthenia gravis (MG) is a rare neuromuscular disorder. Symptoms can range from ptosis only to life threatening myasthenic crisis. Thymectomy is recommended for anti-acetylcholine receptor-antibody positive patients with early-onset MG. Here, we investigated prognostic factors shaping therapeutic outcomes of thymectomy to improve patient stratification.

METHODS

We retrospectively collected single-center data from a specialized center for MG from all consecutive adult patients that underwent thymectomy from 01/2012 to 12/2020. We selected patients with thymoma-associated and non-thymomatous MG for further investigations. We analyzed the patient collective regarding perioperative parameters in relation to the surgical approach. Furthermore, we investigated the dynamics of the anti-acetylcholine receptor-antibody titers and concurrent immunosuppressive therapies, as well as the therapeutic outcomes in dependence of clinical classifications.

RESULTS

Of 137 patients 94 were included for further analysis. We used a minimally invasive approach in 73 patients, whereas 21 patients underwent sternotomy. A total of 45 patients were classified as early-onset MG (EOMG), 28 as late-onset MG (LOMG) and 21 as thymoma-associated MG (TAMG). The groups differed in terms of age at diagnosis (EOMG: 31.1 ± 12.2 years; LOMG: 59.8 ± 13.7 years; TAMG: 58.6 ± 16.7 years; p < 0.001). Patients with EOMG and TAMG were more often female than patients in the LOMG group (EOMG: 75.6%; LOMG: 42.9%; TAMG: 61.9%; p = 0.018). There were no significant differences in outcome scores (quantitative MG; MG activities of daily living; MG Quality of Live) with a median follow-up of 46 months. However, Complete Stable Remission was achieved significantly more frequently in the EOMG group than in the other two groups (p = 0.031). At the same time, symptoms seem to improve similarly in all three groups (p = 0.25).

CONCLUSION

Our study confirms the benefit of thymectomy in the therapy of MG. Both, the concentration of acetylcholine receptor antibodies and the necessary dosage of cortisone therapy show a continuous regression after thymectomy in the overall cohort. Beyond EOMG, groups of LOMG and thymomatous MG responded to thymectomy as well, but therapy success was less pronounced and delayed compared to the EOMG subgroup. Thymectomy is a mainstay of MG therapy to be considered in all subgroups of MG patients investigated.

Poor responses and adverse outcomes of myasthenia gravis after thymectomy: Predicting factors and immunological implications

Myasthenia gravis (MG) has been recognized as a series of heterogeneous but treatable autoimmune conditions. As one of the indispensable therapies, thymectomy can achieve favorable prognosis especially in early-onset generalized MG patients with seropositive acetylcholine receptor antibody. However, poor outcomes, including worsening or relapse of MG, postoperative myasthenic crisis and even post-thymectomy MG, are also observed in certain scenarios. The responses to thymectomy may be associated with the general characteristics of patients, disease conditions of MG, autoantibody profiles, native or ectopic thymic pathologies, surgical-related factors, pharmacotherapy and other adjuvant modalities, and the presence of comorbidities and complications. However, in addition to these variations among individuals, pathological remnants and the abnormal immunological milieu and responses potentially represent major mechanisms that underlie the detrimental neurological outcomes after thymectomy. We underscore these plausible risk factors and discuss the immunological implications therein, which may be conducive to better managing the indications for thymectomy, to avoiding modifiable risk factors of poor responses and adverse outcomes, and to developing post-thymectomy preventive and therapeutic strategies for MG.

[Thymic hyperplasia: A study of 46 cases]

BACKGROUND

Thymic hyperplasia presents as an anterior mediastinal mass and poses important diagnostic and therapeutic challenge. Two types of thymic hyperplasia are described: true hyperplasia and follicular hyperplasie. Literature data are peculiar concerning both entities. We aimed to describe the clinical and microscopic characteristics of thymic hyperplasia through a single institution experience during an 11-year-period.

METHODS

Thymic hyperplasia diagnosed during the period between 2009 and 2020 were included.

RESULTS

In all, 46 thymic hyperplasias were diagnosed. The 46 patients consisted in 33 women and 13 men with a mean age of 30 years. Microscopic diagnosis concluded to a follicular hyperplasia in 12 cases and a true thymic hyperplasia in 34 cases. The diagnosis of true thymic hyperplasia posed a diagnostic challenge with an involuted thymus in 1 case and a thymolipoma in 1 case. The confrontation with the clinical data allowed retaining the diagnosis.

CONCLUSION

The diagnosis of thymic hyperplasia is based on microscopic features. The confrontation with clinical data and the measurements of the thymus according to the age allow to retain the diagnosis in most challenging cases.

[Rethymectomy in patients with myasthenia gravis and recurrent thymoma]

OBJECTIVE

To analyze efficacy and safety of rethymectomy in patients with pathology of thymus.

MATERIAL AND METHODS

Nine patients (2 males and 7 females) underwent rethymectomy in the thoracic surgery department of the Hertzen Research Institute of Oncology for the period from March 2009 to December 2019. Initial thymectomy for myasthenia gravis was performed in 6 patients, for thymoma without myasthenia - in 3 patients. Age of patients varied from 27 to 75 years (median 42.8 years). Myasthenia manifested at the age of 25-61 years (median 29.2 years). Period between manifestation and thymectomy varied from 6 to 24 months (median 12.6 months). MGFA grade IIIa was in 1 patient, grade IIIb - in 1, grade IVa - in 1, grade IVb - in 2, grade V - in 1 patient. Rethymectomy was performed via sternotomy in 4 cases, through thoracoscopy - in 5 patients.

RESULTS

Postoperative complications occurred in 2 (22.2%) patients. Biopsy revealed residual thymic tissue in all patients. Median follow-up after rethymectomy was 30.2 months (range 12-132 months). Complete stable remission was achieved in 3 (50.0%) patients, remission - in 2 cases, partial remission - in 1 patient. Median dose of steroids before rethymectomy was 40 mg (range 16-96 mg), median dose after rethymectomy - 8 mg (range 0-24 mg). Differences were significant (p=0.04). All patients operated on for thymoma or recurrence are alive within 12-124 months after rethymectomy.

CONCLUSION

Rethymectomy is a safe and effective treatment option for patients with refractory myasthenia gravis (especially in case of detected residual thymic tissue) or recurrent thymoma. Radical surgery for recurrent thymoma ensures favorable survival.

[The value of thymectomy in the treatment of non-thymomatous myasthenia gravis]

The value of thymectomy in the treatment of non-thymomatous myasthenia gravis has been controversially discussed. The relatively low incidence and prevalence of this disease, the inconsistent documentation in various studies and the necessity of a long-term follow-up to assess the therapeutic effects has made the generation of valid data difficult. The publication in 2016 of the MGTX trial in the New England Journal of Medicine delivered the first randomized controlled data in which patients aged 18-65 years with generalized myasthenia gravis and positive for acetylcholine receptor antibodies showed a significant benefit after surgical resection of the thymus via median sternotomy. Despite a lack of validation of the advantages of thymectomy by minimally invasive surgery from randomized controlled studies, this technique seems to positively influence the outcome of certain patient groups in a similar way. Video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS) using subxyphoidal and transcervical access routes showed not only esthetic advantages but also showed no relevant inferiority in the influence on clinical outcomes of myasthenia gravis compared to median sternotomy; however, not only the benefits and the esthetic results show differences but also the advantages in the various subtypes of myasthenia gravis show divergent prospects of success with respect to remission. The clinical spectrum of myasthenia is heterogeneous with respect to the occurrence of antibodies, the body region affected and the age of the patient at first diagnosis. Ultimately, thymectomy is an effective causal treatment of myasthenia gravis.

Outcomes After Transcervical Thymectomy for Ocular Myasthenia Gravis: A Retrospective Cohort Study With Inverse Probability Weighting

BACKGROUND

The benefit of thymectomy in reducing requirement for corticosteroids, symptom severity, need for immunosuppression, and hospitalization rates in patients with seropositive generalized myasthenia has recently been established. It is unclear whether this benefit applies to patients with myasthenia and purely ocular manifestations (ocular myasthenia gravis [OMG]).

METHODS

We conducted a retrospective single-center cohort study of patients with OMG. Patients were included if their diagnosis was confirmed by acetylcholine receptor or muscle-specific kinase antibodies, abnormal electrophysiology, or a positive edrophonium test and at least 1 year of clinical follow-up. At each visit, the presence and severity of ocular and generalized symptoms was ascertained using a 4-point scale. Prednisone dose, steroid-sparing agent use, and need for intravenous immunoglobulin or plasmapheresis were recorded. The effect of thymectomy on time-weighted prednisone dose and symptom severity score was assessed using linear regression models. To adjust for nonrandomization of thymectomy, we used inverse probability weighting using a propensity score model derived from the prethymectomy observation period for thymectomy patients and a 6-month lead-in period for nonthymectomy patients that incorporated age, sex, acetylcholine receptor antibody seropositivity, disease severity (as defined by both symptom severity and treatment requirement), and treating physician preferences.

RESULTS

Eighty-two patients (30 with thymectomy and 52 nonthymectomy) were included. In unadjusted analyses, time-weighted daily prednisone dose was 2.9 mg higher with thymectomy compared with nonthymectomy (95% CI: 0.2-5.7), but after inverse probability weighting, this was no longer statistically significant (difference = 1.7 mg, 95% CI: -0.8 to 4.2). There was no statistically significant difference in symptom severity score (adjusted difference = 0.35, 95% CI: -0.02 to 0.72) or risk of generalization (P = 0.22).

CONCLUSIONS

In this retrospective study that used statistical techniques to account for nonrandomization, no significant differences in prednisone dose or symptom severity after thymectomy in ocular myasthenia were demonstrated.

Subxiphoid completion thymectomy for refractory non-thymomatous myasthenia gravis

Background

Completion thymectomy may be performed in patients with non-thymomatous refractory myasthenia gravis (MG) to allow a complete and definitive clearance from residual thymic tissue located in the mediastinum or in lower neck. Hereby we present our short- and long-term results of completion thymectomy using subxiphoid video-assisted thoracoscopy.

Methods

Between July 2010 and December 2017, 15 consecutive patients with refractory non-thymomatous myasthenia, 8 women and 7 men with a median age of 44 [interquartile range (IQR) 38.5–53.5] years, underwent video-thoracoscopic completion thymectomy through a subxiphoid approach.

Results

Positron emission tomography (PET) showed mildly avid areas [standardized uptake value (SUV) more than or equal to 1.8] in 11 instances. Median operative time was 106 (IQR, 77–141) minutes. No operative deaths nor major morbidity occurred. Mean 1-day postoperative Visual Analogue Scale value was 2.53±0.63. Median hospital stay was 2 (IQR, 1–3.5) days. A significant decrease of the anti-acetylcholine receptor antibodies was observed after 1 month [median percentage changes −67% (IQR, −39% to −83%)]. Median follow-up was 45 (IQR, 21–58) months. At the most recent follow-up complete stable remission was achieved in 5 patients. Another 9 patients had significant improvement in bulbar and limb function, requiring lower doses of corticosteroids and anticholinesterase drugs. Only one patient remained clinically stable albeit drug doses were reduced. One-month postoperative drop of anti-acetylcholine receptor antibodies was significantly correlated with complete stable remission (P=0.002).

Conclusions

This initial experience confirms that removal of ectopic and residual thymus through a subxiphoid approach can reduce anti-acetylcholine receptor antibody titer correlating to good outcome of refractory MG.

Robotic-Extended Rethymectomy for Refractory Myasthenia Gravis: A Case Series

To assess the safety and efficacy of robotic-extended rethymectomy in selected refractory myasthenia gravis (MG) patients with suspected residual thymic tissue. Robotic-extended rethymectomy was performed in 6 MG patients with seropositive acetylcholine receptors (AChR) antibody who had undergone a previous thymectomy (1 cervicotomy, 2 video-assisted thoracoscopic surgeries, and 3 sternotomies). The median observation time before robotic rethymectomy was 108 (24-171) months. The main outcomes were perioperative morbidity, mortality, conversion to open surgery, and clinical outcomes according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS). Before rethymectomy, all patients required immunosuppressants and 5 patients (83.3%) required intravenous immune globulin and/or plasma exchange to control the symptoms. The median specimen weight was 24.5 (14-144) g after rethymectomy, and residual thymic tissue was found in 5 patients (83.3%). No conversion to open surgery or perioperative morbidity and mortality was observed. With a median follow-up time of 46.5 (13-155) months, 3 patients (50%) achieved "improved" and 3 (50%) were "unchanged" according to the MGFA-PIS. Compared with preoperative use, the median daily dose of corticosteroids statistically decreased (25 [7.5-60] vs 0 [0-5] mg, P = 0.002) without significant change in azathioprine use (100 [0-200] vs 50 [0-150] mg, P = 0.360). AChR antibody positive MG patients with a treatment refractory long-term course after thymectomy might have remaining thymic tissue with the 2 commonly associated thymus pathologies, thymoma, and follicular hyperplasia. Robotic-extended rethymectomy might be considered as a safe and beneficial treatment option in these patients.

Unraveling the role of ectopic thymic tissue in patients undergoing thymectomy for myasthenia gravis

Extended thymectomy has been considered the goal of surgery for myasthenia gravis (MG) mainly due to the existence of ectopic thymic tissue. Recently, ectopic thymic tissue has attracted increasing attention in patients with MG following thymectomy. However, the specific role of ectopic thymic tissue in patients with MG is still under debate. A systematic search of the literature was performed on PubMed and Medline according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISM) statement. Studies evaluating the rate of ectopic thymic tissue in patients with MG with or without thymoma were included. Extraction was performed for all eligible studies and the rate of ectopic thymic tissue at common locations was calculated. Eighteen out of fifty-nine studies were eligible for inclusion, of which ten studies reported the common locations of ectopic thymic tissue in mediastinal fat. Of these ten studies, the presence of ectopic thymic tissue was investigated in different anatomical locations in 882 patients, of whom, 509 patients (58%) have at least one positive location with the most common ones being anterior mediastinal fat, pericardiophrenic angles, aortopulmonary window, cervical region (pretracheal fat) and lateral to phrenic nerves. On the other hand, nine studies analyzed the influence of the presence of ectopic thymic tissue on the clinical outcomes of MG patients. Of these, six found that the presence of ectopic thymic tissue in MG patients is a significant predictor of poor outcome after thymectomy, however, the other three did not find a significance. Altogether, ectopic thymic tissue is likely to present in more than a half of patients undergoing thymectomy for MG. Besides, MG patients who have ectopic thymic tissue after thymectomy do not seem to have as good outcome as those who have not.

Does repeat thymectomy improve symptoms in patients with refractory myasthenia gravis?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was: Does repeat thymectomy improve symptoms in patients with refractory myasthenia gravis after thymectomy? A total of 189 papers were found using the reported search, of which seven represented the best evidence to answer the clinical question. The outcome measures included operative mortality and morbidity, as well as long-term remission rate. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. All the studies were small (4-21 patients), retrospective, single institutional case series. There was considerable heterogeneity in the studies. The interval between the first and second operation ranged from less than a year to over 10 years. The operative approach of the initial operation included transcervical, trans-sternal and substernal approaches. The maximal medical therapy received by the patients prior to reoperation varied from anticholinesterase alone to cytotoxic therapy and regular plasmapheresis. The severity of symptoms ranged from Osserman Class IIa to V. The operative approach to re-thymectomy included resternotomy, thoracoscopy and a combination of both. There was no perioperative mortality. One study reported injury to the innominate vein at resternotomy in 3 (14.3%) patients. One study reported myasthenic crisis in 2 patients in the postoperative period. Only one study reported complete remission in 2 patients. In general, however, 52-95% of patients reported some improvement. There was no consistent, objective measure of improvement in these studies. We conclude that repeat thymectomy for patients with refractory myasthenia gravis after previous thymectomy is safe especially for patients whose first procedure was transcervical. Complete remissions are rare but, in these small series, 60-70% of patients report improvement. Clinical improvement appears to be associated with the presence of residual thymic tissue at the second operation, but these cannot be reliably identified on preoperative imaging. Patient selection remains driven by symptoms.

Extended transsternal thymectomy for the treatment of ocular myasthenia gravis

BACKGROUND

The optimal treatment for ocular myasthenia gravis (OMG) remains controversial. We conducted a review of the long-term clinical outcomes of Chinese patients with OMG after extended transsternal thymectomy (ETT) to determine the efficacy of this procedure as a treatment for OMG.

METHODS

We reviewed the cases of 115 consecutive patients with OMG who underwent ETT at our Myasthenia Gravis Research Center between January 2006 and December 2008. Extended transsternal thymectomy was done in patients who had thymoma, resistance to pyridostigmine therapy, or relapse after immunosuppressive therapy. The patients' postoperative responses were defined as strict complete remission (SCR), consisting of an asymptomatic status without medication for more than 12 months; general complete remission (GCR), consisting of an asymptomatic status with low-dose single-drug therapy or without medication for more than 12 months; or improvement, consisting of fewer symptoms or less of a need for medication than before surgery.

RESULTS

The overall complication rate was 7.8%. None of the patients experienced a myasthenic crisis, progression to generalized myasthenia gravis, or mortality. Hyperplasia of the thymus was present in 106 of the 115 patients (92.2%). Among 110 patients on whom follow-up was done postoperatively, 29 (26.4%) were in SCR, 64 (58.2%) showed improvement, 7 (6.4%) remained unchanged, and 10 (9.1%) had a worsening of their conditions. Kaplan-Meier analysis revealed rates of GCR of 41.8% at 24 months and 47.3% at 48 months after surgery, and rates of SCR of 24.5% at 24 months and 26.4% at 48 months. Both univariate analysis and multivariate Cox regression analysis revealed that only preoperative duration of illness was positively associated with GCR (p < 0.001).

CONCLUSIONS

The results of the review indicate that ETT is a safe and effective treatment for OMG, especially in patients with illness of shorter duration.

Clinical evaluation and management of myasthenia gravis

Myasthenia gravis (MG) is a syndrome of fluctuating skeletal muscle weakness that worsens with use and improves with rest. Eye, facial, oropharyngeal, axial, and limb muscles may be involved in varying combinations and degrees of severity. Its etiology is heterogeneous, divided initially between those rare congenital myasthenic syndromes, which are genetic, and the bulk of MG, which is acquired and autoimmune. The autoimmune conditions are divided in turn between those that possess measurable serum acetylcholine receptor (AChR) antibodies and a smaller group that does not. The latter group includes those MG patients who have serum antibodies to muscle-specific tyrosine kinase (MuSK). Therapeutic considerations differ for early-onset MG, late-onset MG, and MG associated with the presence of a thymoma. Most MG patients can be treated effectively, but there is still a need for more specific immunological approaches.

Thymectomy for myasthenia gravis: analysis of controversies--patient management

BACKGROUND

Debate continues regarding the effectiveness of thymectomy in the treatment of nonthymomatous autoimmune myasthenia gravis primarily because there have been no controlled prospective studies. The debate is compounded by the lack of recognition that all thymectomies are not equal in extent or effectiveness and by the fact that all the studies are retrospective without common definitions of myasthenia gravis manifestations or response to therapy. In addition, the analysis of data is often inappropriate.

REVIEW SUMMARY

Evidence is presented demonstrating that the extent of the various thymic resectional techniques is very variable and often incomplete and that the more complete the thymic resection the better the results. The indications for thymectomy, the selection of the technique of the resection, the reoperations issue, the perioperative management of the myasthenia gravis patient, morbidity and mortality, and appropriate methods of outcome research are also reviewed.

CONCLUSION

In view of the impressive results associated with a complete thymic resection in the treatment of myasthenia gravis, patients should not be denied this operation because of lack of prospective proof to-date, and when a thymectomy is performed a total resection is indicated.

Thymectomy by partial sternotomy for the treatment of myasthenia gravis

BACKGROUND

Myasthenia gravis is an autoimmune disease characterized by weakness and fatigue of voluntary muscles. Surgical treatment of choice for myasthenia gravis has been thymectomy. However, thymectomy indications and surgical approach are still controversial. The purpose of this study is to evaluate the efficacy of partial median sternotomy approach to the thymus.

METHODS

From 1973 to 1999, 478 patients with myasthenia gravis underwent thymectomy through a partial median sternotomy.

RESULTS

Sixty-one patients (12.7%) had complete remission of symptoms, 299 (62.5%) had a significant improvement, and 83 (17.4%), a mild improvement; whereas 35 patients (7.4%) had no improvement of clinical symptoms.

CONCLUSIONS

Partial median sternotomy has shown to be a useful surgical approach to the thymus, as demonstrated by the good functional and aesthetic results, associated with low morbidity and no mortality.

Thoracoscopic completion thymectomy in refractory nonthymomatous myasthenia

BACKGROUND

The aim of this study was to assess the efficacy of thoracoscopic completion thymectomy in patients with refractory nonthymomatous myasthenia.

METHODS

Eight patients were operated upon after transcervical (n = 6) or transsternal (n = 2) thymectomy. The mean interval between operations was 129 months. Every patient was completely disabled despite treatment with large dosages of prednisone in combination with pyridostigmine (n = 5) or azathioprine (n = 3) and with repeated plasma exchanges.

RESULTS

Gross (n = 5) or microscopic (n = 3) residual thymic tissue was found in all patients. There was no mortality, but morbidity included 2 patients with postoperative myasthenic crisis requiring reintubation and mechanical ventilation. The mean hospital stay was 4.75 days. The mean follow-up was 28.3 months. At the last follow-up, 6 patients had achieved symptomatic improvement as expressed by significant change in mean Osserman class (3.37 versus 2.12, p = 0.03), and prednisone dosage (43 versus 20 mg/d, p = 0.03). Conversely, there was no difference in dosage of pyridostigmine and azathioprine or in number of exchange cycles.

CONCLUSIONS

Our results suggest that thoracoscopic completion thymectomy may be beneficial for selected patients with refractory nonthymomatous myasthenia.

Myasthenia gravis

Myasthenia Gravis is a disorder of neuromuscular function resulting from an immunologically based premature destruction of acetylcholine receptors. The disease is characterized clinically by variable weakness accentuated by repetitive muscular activity and usually responding to the administration of acetylcholinesterase inhibitors. Myasthenia Gravis is a complex disease and requires understanding of the many facets of its natural history and immunological basis to ensure optimal individual patient management. The long-term goal is control of the immunological imbalance; treatment regimens include thymectomy, corticosteroids, azathioprine, and plasmapheresis. The common use of acetylcholinesterase inhibitors provides symptomatic relief during variable daily muscular activity. Disability due to myasthenia gravis is to a large extent reversible and death is preventable. Early recognition of myasthenia gravis and appropriate treatment are often rewarded by remission that may be permanent.

Effects of thymectomy in myasthenia gravis

Factors influencing onset of remission in myasthenia gravis were evaluated in 2062 patients, of whom 962 had had thymectomy. Multivariate analysis showed that appearance of early remissions among all patients was significantly and independently influenced by thymectomy, by milder disease, and by absence of coexisting thymomas. Patients with mild generalized symptoms treated with thymectomy reached remission more frequently, even when compared with those with ocular myasthenia treated without surgery. Short duration of disease before thymectomy in mild cases was another factor associated with earlier remissions. Mortality for all patients was significantly and independently influenced by severity of symptoms, age, associated thymomas, and failure to remove the thymus. Patients without thymectomy and with thymomas had, in addition, earlier onset of extrathymic neoplasms. Morbidity after the transcervical approach was minimal. This study demonstrates that early thymectomy by the transcervical approach, when technically feasible, has significant clinical advantages over the transthoracic approach and should be advocated for all patients with myasthenia gravis, including those with ocular disease.

Aggressive surgical approach for drug-free remission from myasthenia gravis

A series of 27 patients with generalized myasthenia gravis is presented. All patients were treated by a sternal split and extended thymectomy and radical mediastinal dissection. The overall drug-free remission rate was 63%, although three additional patients are likely to achieve drug-free remission in the near future, with the total drug-free remission rate then being 74%. Of the remaining patients, all but three improved and require decreased medication, for an improvement rate of approximately 90%. One patient who has not improved had an invasive malignant thymoma. Drug-free remission was achieved in 46% of the male patients and in 82% of the female patients despite that the mean duration of disease was greater than 3.5 years. There was one serious complication, that of sterile sternal dehiscence. There was no mortality. The results suggest that an aggressive, radical surgical approach to myasthenia gravis, even in a group of patients considered somewhat less favorable because of a relatively long duration of disease, can result in a high percentage of drug-free remissions. Radical surgery for myasthenia gravis appears to be the treatment of choice, with medical therapy being reserved for those patients who are not likely to survive operation.

Thymic hyperplasia. II. Lymphofollicular hyperplasia of the thymus. An immunohistologic study

The so-called lymphofollicular hyperplasia, which is caused by the occurrence of hyperplastic lymph follicles within the organ, is constantly associated with autoimmune diseases (e.g., myasthenia gravis) and in rare instances with malignant tumors. The architecture of lymphofollicular hyperplasia was studied immunohistochemically using antibodies against epithelial, vascular, lymphocytic, and histiocytic antigens. There is evidence, that the configuration, microtopography, cellular composition, and immunohistological findings of the lymph follicles with germinal centers in the myasthenic thymus are essentially the same as in those occurring in lymph nodes and in other lymphatic tissue. Furthermore it could be shown that the follicles originate in the interlobular septal space and displace the thymic parenchyma by extension.

Recurrence of thymic hyperplasia after trans-sternal thymectomy in myasthenia gravis

A 23-year-old woman with myasthenia gravis underwent thymectomy in September, 1975 by a trans-sternal approach for the removal of an hyperplastic gland. Surgical intervention was followed by marked improvement of her symptoms. Five years later, symptoms recurred. In March, 1982 diagnostic pneumomediastinum disclosed an anterosuperior mediastinal mass which, on excision, proved to be an hyperplastic thymus. This report confirms previous findings of thymus regrowth after surgery. It also demonstrates that surgical techniques using the trans-sternal approach do not guarantee complete removal of the thymus.

Myasthenia gravis with thymoma: analysis of and postoperative prognosis for 65 patients with thymomatous myasthenia gravis

Sixty-five patients with thymomatous myasthenia gravis were investigated. Thymomas were present in 44% of the male patients and 19% of the female patients with myasthenia gravis. The incidence of thymomatous disease in male patients was higher than in female patients in all age groups. Eighty percent of men more than 50 years old and women more than 60 years old had myasthenia gravis with thymoma. Germinal center formation in the thymus of patients with thymomatous myasthenia gravis was positive in 91% and was high grade. The prognosis for patients undergoing extended thymectomy of thymomatous myasthenia gravis was significantly better than in those having transsternal simple thymectomy, but it was worse than the prognosis for patients with nonthymomatous myasthenia gravis. No increase in the rate of remission or palliation was seen one year after thymectomy. It is concluded that early thymectomy is effective in control of myasthenia gravis in thymomatous myasthenia gravis.

Failing transcervical thymectomy in myasthenia gravis. An evaluation of transsternal re-exploration

Twenty cases of failing transcervical thymectomy are reported. They were selected for transsternal re-exploration from a series of 95 patients who had previously undergone transcervical thymectomy because of myasthenia gravis (MG). A specific method for pre-operative detection of remnants of the non-tumorous thymic gland is lacking, but the applied clinical selection criteria were so far reliable: generalized, disabling, fluctuating MG despite cholinesterase inhibitor and/or immunosuppressive treatment, and no or inconsistent improvement after transcervical thymectomy. At transsternal re-exploration the commonest findings were intact lower thymic lobes with persistent venous drainage into the brachiocephalic vein. Presence of thymic tissue was histologically confirmed in all the excised specimens (weight range 10-60, mean 23 g), and the examination showed thymic hyperplasia in 18 cases, fatty involution of the gland in two, and a lympho-epithelial thymoma in one case. The re-operation was followed by objectively registrable improvement in all but one of the 20 patients during observation periods of 8-75 (mean 21) months. There was statistically significant reduction in disability scores (means 8.2-4.9) and in need for anticholinesterase medication (to 67% of pretreatment dose). Immunosuppression became unnecessary in 6 of 11 patients and could be reduced in 4 patients. The incidence of failure in transcervical thymectomy was alarmingly high (27%), and more re-operations are anticipated. Since the transcervical approach involves a high risk of incomplete thymectomy, its use should be abandoned. However, in most of the patients with re-operation, subsequent progress has been sufficiently promising for advocacy of sternotomy whenever the clinical criteria of failure are fulfilled.