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

Abstract

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.

Keywords: Midgut; neuroendocrine tumor; orbital metastasisneuroendocrine tumor.

Figure 1.

(a) Hemorrhagic chemosis of the left lateral conjunctiva and sclera. (b) T2-weighted postcontrast MRI showing a left lateral rectus lesion with central necrosis (arrow).

Figure 2.

(a) Malignant epithelial cells with single uniform round to oval nucleus with inconspicuous nucleoli and modest amounts of pale eosinophilic cytoplasm arranged in solid nests and sheets. The blue arrow shows tumor necrosis. (b) Positive immunostaining for CDx2. (c) Positive immunostaining for synaptophysin. (d) Ki-67 stain with a low proliferative index.