A 32-year-old woman from Delhi presents with a 3-month history of progressive ptosis and diplopia. She reports that symptoms worsen towards the evening and improve after rest. On examination, she has bilateral ptosis that worsens with sustained upward gaze (positive ice pack test). Serum anti-acetylcholine receptor (AChR) antibodies are positive. Chest CT shows a 2 cm anterior mediastinal mass. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis and Rationale **Key Point:** This patient has seropositive myasthenia gravis (MG) with an associated anterior mediastinal mass (thymoma), making thymectomy the definitive surgical intervention. ### Why Thymectomy is Indicated 1. **Thymoma Association**: The presence of a mediastinal mass on imaging in a patient with seropositive MG strongly suggests thymoma (present in ~10–15% of MG patients). 2. **Surgical Benefit**: Thymectomy is the standard of care for MG with thymoma, with remission rates of 30–50% and significant improvement in 80% of patients [cite:Harrison 21e Ch 378]. 3. **Immediate Symptom Control**: Pyridostigmine should be started concurrently to provide rapid symptomatic relief while awaiting surgery. ### Management Algorithm ```mermaid flowchart TD A[Seropositive MG + Mediastinal Mass]:::outcome --> B{Thymoma confirmed?}:::decision B -->|Yes| C[Start Pyridostigmine for symptom control]:::action C --> D[Arrange Thymectomy]:::action D --> E[Remission/Improvement in 80%]:::outcome B -->|No| F[Consider immunosuppression]:::action ``` **High-Yield:** Thymectomy should be performed as soon as feasible in thymoma-associated MG; delaying surgery worsens long-term prognosis. ### Symptomatic Management - **Pyridostigmine**: Acetylcholinesterase inhibitor; provides rapid symptom relief by increasing acetylcholine at the neuromuscular junction. - **Dosing**: 60 mg TDS is standard; can be titrated up to 120 mg TDS based on response. - **Onset**: Symptomatic improvement within hours to days. **Clinical Pearl:** The ice pack test (improvement of ptosis after 2–3 minutes of ice application) is a bedside confirmatory test for MG and was positive in this patient, supporting the diagnosis. ### Why Other Agents Are Not First-Line Here - **IVIG/Plasmapheresis**: Reserved for myasthenic crisis or acute exacerbations; not indicated as primary therapy in stable disease with thymoma. - **Corticosteroids Alone**: May worsen symptoms initially (steroid-induced exacerbation) and are not definitive; used as adjunct after thymectomy or in seronegative MG without thymoma. - **Azathioprine Monotherapy**: A steroid-sparing immunosuppressant; used for long-term control but not as sole therapy in thymoma-associated MG. **Mnemonic: TIMELY** — **T**hymectomy for **I**mmunosuppression, **M**ediastinal mass, **E**arly intervention, **L**ong-term **Y** benefit.