Carcinoid Tumor Metastases to the Extraocular Muscles: MR Imaging and CT Findings and Review of the Literature

Abstract

SUMMARY: Although a relatively rare neoplasm, primary carcinoid tumor has an unusual propensity to metastasize to the orbits. Within the orbit, metastatic EOM lesions have been described in scattered reports in the ophthalmology literature but have received little to no attention in the radiology literature. After a retrospective review, we identified CT and MR imaging studies of 7 patients with carcinoid tumor metastatic to the EOM. Our findings suggest that in patients with known carcinoid tumor, well-defined, round, or fusiform masses of the EOM should strongly suggest metastatic involvement. Our series suggests that bilateral lesions may occur and that any EOM can be involved. Knowledge of this pattern of metastatic disease may spare biopsies in some patients, and with current orbit-sparing therapy for patients with localized orbital disease, early and accurate diagnosis can significantly improve patient outcomes.ABBREVIATIONS: CN VI ϭ cranial nerve VI; EOM ϭ extraocular muscle; IO ϭ inferior oblique; IR ϭ inferior rectus; LR ϭ lateral rectus; MR ϭ medial rectus; MRI ϭ MR imaging; N/A ϭ not applicable; SO ϭ superior oblique; SR ϭ superior rectus C arcinoid tumors are rare neuroendocrine neoplasms derived from enterochromaffin cells, which are found primarily in the gastrointestinal tract and bronchial tree.1,2 Liver metastases are the classic presentation of distant disease, which can lead to carcinoid syndrome (flushing, diarrhea, and wheezing) and right-sided valvular heart disease. However as treatment options improve and survival increases, new metastatic patterns have been increasing in frequency.3 Although rare, metastatic carcinoid to the extraocular muscles has been relatively well described in both retrospective case reports and clinical series in the ophthalmology literature. [4][5][6][7][8][9][10][11][12][13] However, by our review of the radiology literature, there is a single dedicated case report detailing the imaging findings for this entity.14 Even within the ophthalmology literature, only a handful of reports focus exclusively on metastases involving the EOMs. 4,8,15 We present the first series detailing the CT and MR imaging findings of carcinoid tumor metastases to the EOMs. Materials and MethodsA waiver of informed consent was obtained from our institutional review board, and in a manner consistent with Health Insurance Portability and Accountability Act regulations, we retrospectively collected clinical data and CT and MR images available from our institution in patients with known carcinoid tumor. In addition, via a survey of head and neck radiologists from collaborating institutions, additional cases were collected. All imaging analyzed for this study was performed from January 2000 through October of 2010.We found a total of 7 patients with known metastatic disease to the EOMs. The primary inclusion criterion was the presence of EOM lesions in patients with known metastatic carcinoid tumor, though the presence of non-EOM intraorbital disease was not considered an exclusion criterion. ...

Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum

“…They can be round or fusiform when they involve extraocular muscles (Fig 3). In contrast to carcinoid elsewhere, orbital carcinoids show only mild contrast enhancement and are rarely hypointense on T2weighted images (19,20,22).…”

“…Metastatic orbital carcinoid tumors account for only 0.4% of total orbital metastases and constitute approximately 10% of all orbital neoplasms (19). The uveal tract is the most common site of metastasis from bronchial lesions, whereas extraocular muscles are most commonly involved by metastasis from primary gastrointestinal carcinoids (20) and unilateral orbital involvement is more common than bilateral disease. Metastatic orbital carcinoid should be suspected in patients with known metastatic carcinoid who develop symptoms such as diplopia and proptosis, secondary to a mass lesion in the orbit (21).…”

Genetic analysis of an orbital metastasis from a primary hepatic neuroendocrine carcinoma

“…There is a tendency that orbital metastases originate from primary gastrointestinal tract NETs, whereas intraocular metastases arise from primary bronchial NETs (5). Primary hepatic NETs are extremely rare, and orbital metastases from NETs in general have been reported only in a very few cases (5)(6)(7)(8)(9). We present the first case of a primary hepatic NET with an orbital metastasis including the genomic profiles of the two tumours.…”

Orbital Imaging

“…55) are prevalent. [71][72][73] As described in the section on intraconal metastases, signs and symptoms may vary according to the structures involved by the metastatic tumor. However, diplopia is a prevalent symptom when the extraocular muscles are involved.…”