Metastatic neuroendocrine carcinoma presenting with left lateral rectus enlargement and orbital cellulitis

Neuroendocrine tumors (NETs) of the orbit are a rare but increasingly recognized clinical phenomenon. The vast majority of orbital NETs are metastatic, and most metastasize from the gastrointestinal system to the extraocular muscles. While orbital metastasis typically occurs in the setting of a known primary neoplasm, some cases represent the initial manifestation of disease and can precede detection of the primary tumor by many months. We report a 58-year-old woman who presented with diplopia, unilateral orbital pain, erythema, and chemosis as the primary presentation of a metastatic small intestine NET. This case serves as a reminder that identification of orbital NETs should prompt investigation for primary gastrointestinal or pulmonary NETs. Goals of surgery include obtaining a tissue sample, debulking the lesion, and preserving visual function.