A sequence of pathologic events in a patient after thymectomy for myasthenia gravis

Association between systemic lupus erythematosus and myasthenia gravis: A population-based National Study

BACKGROUND

Systemic lupus erythematosus (SLE) and myasthenia gravis (MG) are autoimmune diseases. Previous case reports and case series suggest an association may exist between these diseases, as well as an increased risk of SLE after thymectomy for MG. We undertook this study to determine whether SLE and MG were associated in large cohorts.

METHODS

We searched the IBM Watson Health Explorys platform and the Department of Veterans Affairs Million Veteran Program (MVP) database for diagnoses of SLE and MG. In addition, we examined subjects enrolled in the Lupus Family Registry and Repository (LFRR) as well as controls for a diagnosis of MG.

RESULTS

Among 59,780,210 individuals captured in Explorys, there were 25,750 with MG and 65,370 with SLE. 370 subjects had both. Those with MG were >10 times more likely to have SLE than those without MG. Those with both diseases were more likely to be women, African American, and at a younger age than MG subjects without SLE. In addition, the MG patients who underwent thymectomy had an increased risk of SLE compared to MG patients who had not undergone thymectomy (OR 3.11, 95% CI: 2.12 to 4.55). Autoimmune diseases such as pernicious anemia and miscellaneous comorbidities such as chronic kidney disease were significantly more common in MG patients who developed SLE. In the MVP, SLE and MG were also significantly associated. Association of SLE and MG in a large SLE cohort with rigorous SLE classification confirmed the association of SLE with MG at a similar level.

CONCLUSION

While the number of patients with both MG and SLE is small, SLE and MG are strongly associated together in very large databases and a large SLE cohort.

Mixed connective tissue disease after thymectomy in refractory myasthenia gravis

Connective tissue diseases, including systemic lupus erythematosus (SLE) and systemic sclerosis are classic models of autoimmunity; diseases with large-scale loss of tolerance and subsequent development of pathogenic autoreactive lymphocytes and tissue targeting autoantibodies. Here we report a case of mixed connective tissue disease, with features of systemic lupus erythematosus and systemic sclerosis developing in a patient 10 years post thymectomy for myasthenia gravis. The patient developed acute cutaneous lupus, Raynaud's with digital ulcers, arthritis and lymphopenia. Her myasthenia continued to be resistant to treatment and her rheumatic disease progressed despite aggressive therapy. We performed a database search of MEDLINE, EMBASE, Scopus, and Web of Science for articles of similar cases post thymectomy from inception to August 2021, using the terms "systemic lupus erythematosus" (or systemic sclerosis, or connective tissue disease) and "myasthenia gravis" and "thymectomy". We identified 41 cases, 28 of SLE post thymectomy, 8 related to systemic sclerosis, 5 with mixed connective tissue disease and highlighted their different presentation and serology. We explore the role of the thymus, tolerance and myasthenia gravis in the development of connective tissue disease. This highlights the complexity of concurrent autoimmune diseases and their autoantibodies.

[Thymoma and autoimmune diseases]

The association between thymoma and autoimmunity is well known. Besides myasthenia gravis, which is found in 15 to 20% of patients with thymoma, other autoimmune diseases have been reported: erythroblastopenia, systemic lupus erythematosus, inflammatory myopathies, thyroid disorders, Isaac's syndrome or Good's syndrome. More anecdotally, Morvan's syndrome, limbic encephalitis, other autoimmune cytopenias, autoimmune hepatitis, and bullous skin diseases (pemphigus, lichen) have been reported. Autoimmune diseases occur most often before thymectomy, but they can be discovered at the time of surgery or later. Two situations require the systematic investigation of a thymoma: the occurrence of myasthenia gravis or autoimmune erythroblastopenia. Nevertheless, the late onset of systemic lupus erythematosus or the association of several autoimmune manifestations should lead to look for a thymoma. Neither the characteristics of the patients nor the pathological data can predict the occurrence of an autoimmune disease after thymectomy. Thus, thymectomy usefulness in the course of the autoimmune disease, except myasthenia gravis, has not been demonstrated. This seems to indicate the preponderant role of self-reactive T lymphocytes distributed in the peripheral immune system prior to surgery. Given the high infectious morbidity in patients with thymoma, immunoglobulin replacement therapy should be considered in patients with hypogammaglobulinemia who receive immunosuppressive therapy, even in the absence of prior infection.

Lupus Nephritis with Thymoma Managed by Thoracoscopic Surgery and Prednisolone

A 48-year-old woman was admitted to our hospital to undergo evaluation for fatigue, severe weight loss, and nephrotic range proteinuria. Light microscopy of a renal biopsy specimen revealed class III (A) lupus nephritis, while immunofluorescence and electron microscopy only showed sparse immune deposits with findings that were not typical of lupus nephritis. Computed tomography revealed a mass in the anterior mediastinum, which was resected. The examination of the surgical specimen revealed type A noninvasive thymoma. In combination with thymomectomy, postoperative steroid therapy achieved the prompt remission of lupus nephritis. In this patient, thymoma-related autoimmunity may have contributed to the exacerbation of lupus nephritis.

Systemic lupus erythematosus followed by myasthenia gravis: a rare association

Systemic lupus erythematosus (SLE) and myasthenia gravis (MG) are autoimmune diseases, their association in the same patient being rarely described. Here, we report a case of SLE in a 19-year-old girl who within 2 years of the diagnosis of SLE developed MG, and underwent thymectomy for a benign thymoma immediately thereafter.

The association of systemic lupus erythematosus and myasthenia gravis: a series of 17 cases, with a special focus on hydroxychloroquine use and a review of the literature

The coexistence of systemic lupus erythematosus (SLE) and myasthenia gravis (MG) is rarely reported, and most of the published studies are case reports. Hydroxychloroquine, an antimalarial agent, is an essential treatment in patients with SLE but special caution is recommended when used in MG patients. We retrospectively analyzed the clinical features, laboratory findings, and outcome of 17 patients with both diseases with a special focus regarding hydroxychloroquine use and with a review of the literature. All patients were women. The mean age at MG onset and SLE diagnosis was 34.5 [14-64] and 37.8 [18-72] years, respectively. The presenting symptoms of MG were limb weakness (94%), ocular (88%) and bulbar involvement (53%). Autoantibodies against the acetylcholine receptor were positive in 94% of cases. The main manifestations of SLE included arthritis (88%), cytopenias (53%) and skin rash (41%). Treatment of SLE required hydroxychloroquine (94%), steroids (47%) and immunosuppressive drugs (18%). Among eight patients (47%) who developed MG after initiation of hydroxychloroquine, the question of induction of MG by hydroxychloroquine was raised in one patient. On the other hand, an exacerbation of myasthenic symptoms was only seen in one of the eight patients who received hydroxychloroquine after the diagnosis of MG. Including our cases, we reviewed a total of 70 patients with SLE and MG. Compared with a large series of 1,000 unselected SLE patients, those with associated MG were older, had lower incidence of cutaneous, renal, and neurological manifestations, and higher frequency of anticardiolipin antibodies and lupus anticoagulant. In conclusion, the clinical pattern of patients with SLE and MG seems to be characterized by a less severe course of SLE and higher frequency of antiphospholipid antibodies. Hydroxychloroquine treatment appears to be safe in this setting.