METHODS: A retrospective review of 31 patients who underwent biopsy for extraocular muscle enlargement. Characteristics, including signs, symptoms, imaging findings, and histopathological assessment were examined.
RESULTS: Chronic inflammatory disorders represented the most common cause of the muscle enlargement followed by malignancy/metastasis. Multiple muscle involvement was more consistent with benign diseases, whereas single muscle involvement was more consistent with malignant causes. Positive predictive value of muscle biopsy was 0.52 for determining a specific cause of the muscle enlargement.
CONCLUSIONS: Muscle biopsy is the standard for diagnosis in patients with extraocular muscle enlargement. This diagnostic test should be performed in every case of non-resolving muscle enlargement, with a specific diagnosis being made in over half of cases.