Differential Diagnosis for a Woman with Eyelid Swelling and Proximal Muscle Weakness

Single Most Likely Diagnosis

• Thyroid Ophthalmopathy with Hypothyroid Myopathy: This condition is characterized by eyelid swelling due to inflammation and proximal muscle weakness due to hypothyroidism. The combination of these symptoms, especially in a woman, points towards a thyroid-related issue, which is common and can cause both ocular and muscular symptoms.

Other Likely Diagnoses

• Dermatomyositis: An inflammatory disease characterized by skin rash and muscle weakness. The eyelid swelling could be part of the dermatological manifestations, and the proximal muscle weakness is a hallmark of the disease.
• Graves' Disease: Although primarily known for causing hyperthyroidism, Graves' disease can also lead to thyroid ophthalmopathy, which might present with eyelid swelling. However, the muscle weakness in Graves' is less common than in hypothyroidism but can occur.
• Sarcoidosis: This condition can cause uveitis and other ocular symptoms, including eyelid swelling, and can also lead to muscle weakness due to granulomatous inflammation affecting various parts of the body.

Do Not Miss Diagnoses

• Lymphoma: Although less likely, lymphoma can cause a wide range of symptoms, including eyelid swelling due to orbital involvement and muscle weakness due to systemic disease or paraneoplastic syndromes. Missing this diagnosis could be fatal.
• Wegener's Granulomatosis (Granulomatosis with Polyangiitis): This is a vasculitis that can affect various parts of the body, including the eyes (causing eyelid swelling) and muscles, leading to weakness. It's a serious condition that requires prompt treatment.
• Myasthenia Gravis: An autoimmune disease that can cause muscle weakness, including eyelid muscles, leading to ptosis (drooping eyelids), which might be mistaken for swelling. It's crucial to diagnose this condition due to its treatable nature and potential for severe respiratory complications if left untreated.

Rare Diagnoses

• Mitochondrial Myopathies: These are a group of disorders caused by mutations in the mitochondrial DNA affecting muscle tissue, leading to weakness. Some forms can also affect the eyes, but this would be a less common presentation.
• Oculopharyngeal Muscular Dystrophy: A rare genetic disorder that affects the muscles of the eyes (leading to ptosis) and the pharynx, potentially causing swallowing difficulties. It's a rare condition but should be considered in the differential diagnosis of progressive eyelid and muscle symptoms.