Masquerading Orbital Sarcoidosis with Isolated Extraocular Muscle Involvement

Area of Science:

• Ophthalmology
• Rheumatology
• Pathology

Background:

• Thyroid eye disease (TED) typically presents with specific clinical and autoimmune features.
• Atypical presentations of TED can mimic other orbital inflammatory conditions.
• Autoantibody-negative TED requires a broader differential diagnosis.

Purpose of the Study:

• To report two cases of presumed isolated orbital sarcoidosis in patients initially diagnosed with euthyroid, autoantibody-negative thyroid eye disease.
• To emphasize the diagnostic utility of orbital biopsy in unusual orbitopathy presentations.

Main Methods:

• Retrospective review of two patients with atypical orbitopathy.
• Orbital biopsy with histopathological examination of extraocular muscles.
• Clinical, imaging, and laboratory data analysis.

Main Results:

• Histopathology revealed noncaseating granulomatous inflammation in extraocular muscles, consistent with sarcoidosis.
• One patient had inferior oblique muscle involvement.
• Diagnosis of isolated orbital sarcoidosis was supported by clinical signs, imaging, and biopsy.

Conclusions:

• Orbital sarcoidosis can mimic thyroid eye disease, particularly in autoantibody-negative cases.
• Orbital biopsy is crucial for diagnosing sarcoidosis when clinical presentation or treatment response is atypical for TED.
• A broad differential diagnosis is essential for managing complex orbital inflammatory diseases.