Thymoma-associated multiorgan autoimmunity with cutaneous only presentation: A case report

Coexistence of myasthenia gravis and lichen planus: A case report and systematic review of related case reports from 1971 to 2024

Key Clinical Message

The co-occurrence of myasthenia gravis (MG) and lichen planus (LP) is a rare phenomenon, with only 13 cases reported in the English literature between 1971 and 2024. Patients with MG or LP, regardless of the thymoma status, require close monitoring for other autoimmune diseases.

Abstract

Myasthenia gravis (MG) is an uncommon autoimmune disease, resulting in fatigable muscle weakness in the ocular, bulbar, and respiratory muscles, as well as muscles of the extremities. Lichen planus (LP) is an autoimmune mucocutaneous disease, presenting with pruritic and violaceous plaques on the skin and mucosal surfaces. So far, MG and LP co-occurrence is only reported in anecdotal individuals. This study reports a patient with MG and LP and systematically reviews the English literature on this rare co-occurrence from 1971 to 2024, indicating only 13 cases with similar conditions. A 67-year-old man presented with ocular and progressive bulbar symptoms, a year after being diagnosed with generalized LP. Laboratory evaluations were normal except for the high anti-AchR-Ab titer and a positive ANA titer. Neurologic examinations revealed asymmetric bilateral ptosis, weakness and fatigability in proximal muscles, and a severe reduction in the gag reflex. He was diagnosed with late-onset, seropositive MG. The treatment included pyridostigmine (60 mg, three times daily), intravenous immunoglobulin (25 g daily for 5 days), and oral prednisolone. There was no evidence of thymoma in the chest x-ray and CT scan without contrast. However, a CT scan with contrast was not performed due to the patient's unstable condition. A common autoimmune mechanism may underlie the unclear pathophysiology of MG and LP co-occurrence, with or without thymoma. Patients with MG, LP, or thymoma require close monitoring and assessment for other possible autoimmune diseases.

Erythroderma in a Patient With Thymoma-Associated Myasthenia Gravis

A woman in her 30s with myasthenia gravis diagnosed at age 27 years presented to the emergency department with severe erythroderma over the past 2 months. What is your diagnosis?

Multimodal immunotherapy ameliorates myasthenia gravis preceded by thymoma-associated multiorgan autoimmunity

Thymoma-associated multiorgan autoimmunity (TAMA) is a rare autoimmune disorder associated with thymoma that causes a pathology similar to graft-versus-host disease (GVHD) targeting the skin, digestive organs, and liver. Herein, we report the case of a 38-year-old male with myasthenia gravis (MG) preceded by TAMA. The patient developed intractable diarrhea 2 years before admission. Subsequently, dysphagia, dysarthria, and left blepharoptosis were observed. The patient was admitted to the hospital because of fever and dyspnea, was positive for anti-AChR antibody, and chest-computed tomography revealed thymoma, which led to the diagnosis of thymoma-related MG. Biopsied specimens from the sigmoid colon revealed apoptotic colonopathy with lymphocyte-rich lamina propria. Immunohistochemical staining revealed that the infiltrating cells were predominantly labeled with anti-CD3-antibody. The patient did not show skin lesions or liver dysfunction. Therefore, TAMA limited to the gastrointestinal tract was diagnosed. Although TAMA typically has a poor prognosis, immediate multimodal immunotherapy for MG was successful, resulting in a good outcome for TAMA of this case. TAMA is caused by the inability of the thymoma to suppress self-reactive T lymphocytes, which subsequently leads to a disease that is clinically indistinguishable from GVHD. Based on the characteristics of this case, limited gastrointestinal tract involvement in TAMA without lesions in other organs may lead to a favorable prognosis. TAMA cases lacking skin lesions may present with nonspecific gastrointestinal or liver disease. If a patient with thymoma-associated MG has gastrointestinal symptoms such as diarrhea, TAMA should be considered, and the diagnosis should be made early by pathological evaluation of gastrointestinal tissues.