Myasthenia gravis associated with T helper cell lymphoma

Antibodies Produced by CLL Phenotype B Cells in Patients With Myasthenia Gravis Are Not Directed Against Neuromuscular Endplates

BACKGROUND AND OBJECTIVES

Myasthenia gravis (MG) can in rare cases be an autoimmune phenomenon associated with hematologic malignancies such as chronic lymphocytic leukemia (CLL). It is unclear whether in patients with MG and CLL, the leukemic B cells are the ones directly driving the autoimmune response against neuromuscular endplates.

METHODS

We identified patients with acetylcholine receptor antibody-positive (AChR⁺) MG and CLL or monoclonal B-cell lymphocytosis (MBL), a precursor to CLL, and described their clinical features, including treatment responses. We generated recombinant monoclonal antibodies (mAbs) corresponding to the B-cell receptors of the CLL phenotype B cells and screened them for autoantigen binding.

RESULTS

A computational immune cell screen revealed a subgroup of 5/38 patients with MG and 0/21 healthy controls who displayed a CLL-like B-cell phenotype. In follow-up hematologic flow cytometry, 2 of these 5 patients were diagnosed with an MBL. An additional patient with AChR⁺ MG as a complication of manifest CLL presented at our neuromuscular clinic and was successfully treated with the anti-CD20 therapy obinutuzumab plus chlorambucil. We investigated the specificities of expanding CLL-like B-cell clones to assess a direct causal link between the 2 diseases. However, we observed no reactivity of the clones against the AChR, antigens at the neuromuscular junction, or other common autoantigens.

DISCUSSION

Our study suggests that AChR autoantibodies are produced by nonmalignant, polyclonal B cells The new anti-CD20 treatment obinutuzumab might be considered in effectively treating AChR⁺ MG.

CLASSIFICATION OF EVIDENCE

This is a single case study and provides Class IV evidence that obinutuzumab is safe to use in patients with MG.

Myasthenia Gravis and Large Granular Lymphocytic Leukemia: a rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder sometimes observed in hematologic malignancies as a paraneoplastic syndrome. T-cell Large Granular Lymphocytic Leukemia (T-LGLL) is a rare lymphoproliferative clonal frequently associated with autoimmune disorders. Here we report two patients with T-LGLL who developed MG. In both patients the MG was bulbar without generalized weakness and did not involve the thymus. The treatment of T-LGLL led to the resolution of MG symptoms and decrease in acetylcholine receptor antibody titers in both patients suggesting a causative association.

Myasthenia Gravis Complicated with Peripheral T-cell Lymphoma, Not Otherwise Specified (PTCL-NOS), Following Thymectomy and Longstanding Tacrolimus Therapy

Myasthenia gravis (MG), a neuromuscular junction autoimmune disease, sometimes complicates second malignancies; however, T-cell lymphoproliferative disorders have rarely been reported. A 55-year-old man, who received oral tacrolimus and prednisolone for MG for 16 years after thymectomy, presented with left abdominal pain, lymphadenopathy, and splenomegaly. A lymph node biopsy revealed peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). This is the first report of oral tacrolimus leading to a T-cell lymphoproliferative disorder in patient without a history of transplantation. Physicians should be aware of the possibility of rare T-cell lymphoproliferative disorders, such as PTCL-NOS, occurring as complications in MG patients on immunosuppressive regimens after thymectomy.

Excessive risk of cancer and in particular lymphoid malignancy in myasthenia gravis patients: a population-based cohort study

The exact relationship between myasthenia gravis (MG) and extrathymic malignancies has not been established thus far. Occasional cases of MG have been reported in association with lymphoma or other lymphoproliferative disorders. To determine the risk of extrathymic malignancy with particular attention on lymphoid malignancy for MG patients in a large cohort representing 99% of the Taiwan population, claims data from the Taiwan National Health Insurance Database were used to conduct retrospective cohort analyses. The study cohort comprised 3671 MG patients who were 10-fold frequency matched by age and sex, and assigned the same index year without MG. Cox proportional hazard regression analysis was conducted to estimate the risk of cancer. The MG cohort had a 1.74-fold increased risk of developing cancer compared to the comparison cohort (HR=1.74, 95% CI=1.47-2.05). After adjusting for confounders and relative to the cohort, patients with MG had a 2.27-fold increased risk of developing lymphoid malignancies (HR=2.27, 95% CI=1.06-4.88) and a 118.47-fold increased risk of thymus cancer (HR=118.47, 95%=42.57-329.71). This population based retrospective case-control study confirms and extends previous observations on the association between MG and lymphoid malignancies.

Myasthenia gravis and lymphoblastic lymphoma involving the thymus: a rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disease. An association between thymic epithelial neoplasms and MG is well known. However, it is rarely associated with hematologic malignancies. In particular, very few cases of lymphoblastic lymphoma involving the thymus and MG have been reported. Here we report a case T-cell lymphoblastic lymphoma involving the thymus who developed MG after the initial diagnosis. The patient initially presented with a mediastinal mass which was diagnosed as lymphoblastic lymphoma. MG was diagnosed during leukemic relapse in this patient and was based on clinical presentation and neurophysiologic studies including single fiber electromyography (EMG) and repetitive nerve stimulation tests. In contrast to the other cases with such an association, the myasthenic symptoms presented nine months after the diagnosis of lymphoma by thymectomy. The patient had a highly aggressive clinical course and was resistant to various chemotherapy regimens.

Myasthenia gravis associated with cutaneous lymphoma in a dog

A middle-aged golden retriever presenting with exercise intolerance and multifocal cutaneous nodules was diagnosed as having non-epitheliotropic cutaneous lymphoma with concurrent myasthenia gravis. Treatment with corticosteroids induced short-term remission of the lymphoma and alleviation of myasthenic signs.

Peripheral nervous system and spinal cord involvement in lymphoma

Nine-hundred-eighty-nine patients with diagnosis of lymphoma were studied. Forty-six cases (4.6%) had compressions of the spinal cord or roots. Forty-two patients (4.2%) had Herpes zoster virus infections, which in 6 cases were of disseminated type. The major predisposing factors for infection were: advanced stage of lymphoma, previous systemic chemotherapy and splenectomy. Toxic polyneuropathy secondary to chemotherapy was found in 39 patients (3.9%). In 14 cases, the polyneuropathic symptoms were the main complaint (Group 1), while in the remaining 25 cases the diagnosis was made during neurological consultations because of unrelated symptoms (Group 2). Both groups did not have significant differences in the total dose of chemotherapy received. The electrophysiological studies showed an axonal neuropathy in both groups. The discontinuation of chemotherapy was found to be a limiting factor in the appearance of neuropathic symptoms. Other less frequent forms of involvement were: compression of peripheral nerves or nerve plexi from lymphadenopathies (3 cases), radiation myelopathy (1 case), and Guillain-Barré Syndrome associated with Hodgkin's Lymphoma (1 case).