Pathological Findings in Myasthenia Gravis Patients with Thymic Hyperplasia and Thymoma

Abstract

Thymectomy is routinely carried out in patients with myasthenia gravis (MG) and thymomas. However, there is still a dispute as to whether MG patients with thymic hyperplasia should undergo thymectomy. We aimed to investigate the pathological findings in the thymus in patients with co-existing MG and thymic hyperplasia or thymomas treated with thymectomy, as well as effects of immunosuppression. Thirty-three patients with MG were selected and grouped accordingly: patients with no thymic abnormalities, patients with thymic hyperplasia, and patients with thymomas. All patients were treated with methylprednisolone alongside immunosuppression. A separate cohort of 24 MG patients with thymic hyperplasia or thymomas and treated with thymectomy were selected. As controls, 5 patients with thymomas or thymic carcinoma without MG were selected. Expression of CD5, extracellular regulated protein kinases1/2 mitogen activated protein kinase (ERK1/2MAPKs) and CD95 ligand (FasL) in the thymus was examined. Methylprednisolone and immunosuppressive therapy are highly effective in MG patients with normal thymus tissue and MG patients with thymic hyperplasia compared to MG patients with thymomas alone. CD5 expression was highest in MG patients with thymic hyperplasia, correlating with expression of ERK1/2MAPKs. FasL expression was similar across all groups. Thymomas may be distinguished from thymic hyperplasia by expression of CD5 and ERK1/2MAPKs. Thymectomy is the preferred treatment for MG patients with thymomas but may not be necessary in MG patients with thymic hyperplasia who are treated with immunosuppressive therapy.

Mediastinal tumours and pseudo-tumours: a comprehensive review with emphasis on multidisciplinary approach

“…), the latter is the result of the growth of lymphoid follicles within thymic tissue [7]. Thymic hyperplasia with lymphoid follicles is also associated with autoimmunity (myasthenia gravis) [8]. Other benign diseases include thymic cysts, which may be congenital, developing from remnants of the nasopharyngeal duct or acquired as a consequence of long-lasting inflammatory diseases.…”

LncRNA XLOC_003810 promotes T cell activation and inhibits PD‐1/PD‐L1 expression in patients with myasthenia gravis‐related thymoma

“…There is emerging evidence that the pathogenesis of MG involves the functional status of the thymus gland 2 . More importantly, MG patients have a high risk of developing thymic lesions, including thymoma, thymic hyperplasia and thymic atrophy 3 . Thymoma is defined as a type of benign or low‐grade malignant tumour derived from thymic epithelial cells, occurring in 10%~20% of MG patients.…”

LncRNA XLOC_003810 modulates thymic Th17/Treg balance in myasthenia gravis with thymoma

“…2 More importantly, MG patients have a high risk of developing thymic lesions, including thymoma. 3 Thymoma is defined as a type of benign or low-grade malignant tumour derived from thymic epithelial cells, occurring in 10%-20% of MG patients. Meanwhile, 20%-25% thymoma patients are usually accompanied with some autoimmune disorders including MG. 4 T helper 17 (Th17) cells and regulatory T (Treg) cells are different subsets of CD4 + T cells, which have a distinct differentiation pathway with adverse function.…”

“…Numerous studies have highlighted the roles of long non-coding RNAs (lncRNAs) in immune-related diseases. 3,15 LncRNAs are a class of RNA molecules with a length of more than 200 nt, which participates in various physiological or pathological processes. 16 LncRNAs have been suggested to be implicated in the regulation of Th17/Treg balance.…”

“…The pathogenesis of MG involves the functional status of the thymus gland . More importantly, MG patients have a high risk of developing thymic lesions, including thymoma . Thymoma is defined as a type of benign or low‐grade malignant tumour derived from thymic epithelial cells, occurring in 10%–20% of MG patients.…”