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Case report

an intriguing sign in a patient with an inferior rectus muscle granular cell tumor

Che, Lin MS; He, Pei BS; Fan, Bin PhD; Li, Guang-Yu PhD*

Section Editor(s): NA.,

doi: 10.1097/MD.0000000000013624
Research Article: Clinical Case Report
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Rationale: Occurrence of granulosa cell tumors (GCTs) in the eye are rare and may be diagnosed by imaging examination and immune-histochemical studies. Two common signs of a rectus muscle tumor are the proptosis of the eye ball and the complaint of bi-ocular diploma.

Patient concerns: A 45-year-old man visited our ophthalmology department with an about a 3-year history of vertical diplopia. His visual acuity when looking forward was normal but was severely low when gazing upward.

Diagnosis: Histopathological analysis demonstrated that the encapsulated tumor contained large nested or cord-like cells with small nuclei and abundant eosinophilic cytoplasmic particles. Immunohistochemistry showed that tumor cells strongly expressed CD68, S100 and vimentin, were weakly positive for Ki67, and negative for CK. The tumor was diagnosed as a GCT.

Interventions: The tumor was surgically removed via a transconjunctival approach along inferior rectus muscle.

Outcomes: The severe loss of acuity when gazing upward was ameliorated after surgery, but global mobility did not improve. Long-term follow-up was still needed.

Lessons: Ophthalmologists should be aware that when a patient's visual acuity is normal when looking forward but severely low when gazing upward, it may be a sign of a GCT of the inferior rectus muscle.

Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China.

Correspondence: Guang-Yu Li, Department of Ophthalmology, Second Hospital of Jilin University, Changchun 130041, China (e-mail: liguangyu@aliyun.com).

Abbreviations: CT = computed tomography, EOMs = extraocular muscles, GCTs = granular cell tumors, MRI = magnetic resonance images.

Declarations: Written informed consent was obtained from the patient for publication of this case report and any accompanying images. The need for institutional ethics committee approval was waived because the content of this case report did not require ethics approval.

Funding/Support: The study was funded by the National Natural Science Foundation of China (No. 81570864) and the Natural Science Foundation of Jilin Province (No. 20160101004JC; No.20160414045GH; No.2016J041).

The authors have no conflicts of interest to disclose.

nothing to disclose.

This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0

Received August 8, 2018

Accepted November 19, 2018

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1 Introduction

Orbital rectus muscle tumors, such as orbital rhabdomyosarcoma, intermuscular hemangiomas, and primary orbital lymphoma, are relatively rare. Neoplastic involvement of extraocular muscles may be the result of a primary muscle tumor, local infiltration from an orbital tumor or metastasis. Metastases to the extraocular muscles are uncommon, and are most frequently associated with breast cancer and melanoma.[1] It was believed that granular cell tumors (GCTs) originate from rhabdomyosarcoma cells, but it has been recently confirmed that they are derived from Schwann cells and neurogenic tumor cells.[2,3] Head, neck, underarms, breast, and waist are the most common sites for GCTs. Extraocular muscles were involved in 67.5% of the GCTs, with the most common infiltration, 40.7%, of the inferior rectus muscle.[4]

Rectus muscle tumors can directly restrict globe mobility, and the patients often come to the ophthalmologist with the complaint of biocular diploma. Another sign for a rectus muscle tumor is proptosis of the eye ball due to the mass effect of the tumor.

In the current case, we report an uncommon sign in a patient clinically diagnosed with a GCT of the inferior rectus muscle. His visual activity when looking forward was normal but was severely low when gazing upward. This is the 1st report for such a sign that ophthalmologists should be aware of.

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2 Case

A 45-year-old man visited our ophthalmology department with an about a 3-year history of vertical diplopia. Intriguingly, his best corrected visual acuity was 20/20 in both eyes when looking forward that decreased to hand motion /10 CM when gazing upward. The patient denied any orbital trauma or other ocular diseases, and he had no significant past medical or family history.

External examination showed slight proptosis and upward displacement of the right eye (Fig. 1). There was no palpable mass in periorbital area. Hertel exophthalmometry revealed a 3 mm proptosis on the right side. Globe mobility was complete in the left eye, but infraduction and supraduction was comprimised in the right eye. Slit lamp, fundoscopic, Humphrey visual fields and visual evoked potential examinations of both eyes were unremarkable. The intraocular pressure measured by Goldmann tonometer was 15 mm Hg in both eyes.

Figure 1

Figure 1

Orbital computed tomography (CT) scanning showed enlargement of the right inferior rectus muscle infiltrated by a muscle-density tumor which was about 11 × 17 × 7 mm3 that displaced the globe upward. An axial magnetic resonance images (MRI) view of the orbit revealed a nodule-like tumor derived from the inferior rectus muscle, which was slightly hypo-intense to the extraocular muscles on T1W with a very low central intensity on T2W and a higher intensity along the periphery. Sagittal MRI images showed that the tumor was very close to the optic nerve with almost no gap in between. Enhanced MRI after intravenous contrast administration showed that the tumor was significantly enhanced in the periphery but only slight enhanced in the center (Fig. 2).

Figure 2

Figure 2

The tumor was surgically removed via a transconjunctival approach along inferior rectus muscle. Intraoperatively, the tumor was completely separated from muscle tissue since it was pseudoencapsular. The gross specimen exhibited a firm fibrotic nodule-like and pale-colored mass (Fig. 3). There was no significant improvement in globe mobility after surgery; however, a longer term follow-up is required.

Figure 3

Figure 3

Subsequent histopathological analysis demonstrated that the encapsulated tumor contained large nested or cord-like cells with small nuclei and abundant eosinophilic cytoplasmic particles. Immunohistochemistry showed that tumor cells strongly expressed CD68, S100 and vimentin, were weakly positive for Ki67, and negative for CK (Fig. 4) and was diagnosed as a GCT.

Figure 4

Figure 4

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3 Discussion

The most common complaints of patients with orbital GCT are diplopia, proptosis, and mobility restriction. The GCTs appear as diffuse or oval masses isodense relative to brain tissue in computed tomography (CT) scans. The tumors are isointense in T1-weighted MRI and isointense or hypointense in T2-weighted MRI relative to the extraocular muscles (EOMs), and can be slightly enhanced with contrast administration. Intriguingly, in the current case, the vision of the patient was sharply lower in his right eye when gazing upward which is very rare. Upon further examination with enhanced MRI sagittal imaging, we found a tumor that was very closed to the optic nerve. We speculate that when the eyeball turned upwards, the enlarged tumor contacted the optic nerve leading to a temporal decrease of vision.

Immunohistochemical studies of the patient was consistent with previous reports[4] that showed 100%, 90%, and 66.7% of cases were positive for vimentin, S-100, and CD68, respectively. Therefore, the final diagnosis was a GCT.

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4 Differential diagnosis of rectus muscle diseases

4.1 Graves disease

Graves disease is the most common type of hyperthyroidism. The clinical manifestations may include exophthalmos and extraocular muscles involvement, but the functional diagnosis is mainly based on the increase of thyroid hormone secretion. Orbital CT scans show a thickening of the muscle abdomen without tendon involvement.[5]

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4.2 Rhabdomyosarcoma

Rhabdomyosarcoma is the most common malignancy of soft tissue in children.[6] Since it is highly malignant, the rapid progression of ocular symptoms such as proptosis, eyeball displacement, conjunctival congestion and orbital mass are often major signs. Orbital CT scanning shows enlargement of the abdomen muscle and a local lesion with relative sparing of the tendons.[7] The tumor can be enhanced in MRI images with intravenous contrast administration.

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4.3 Hypertrophic myositis

Hypertrophic extraocular myositis is a type of localized non-specific fibroid pseudo-tumor. The common clinical manifestations of hypertrophic extraocular myositis are acute paroxysmal eye pain, diplopia, ptosis, mild edema of the eyelids, slight protrusion of the eyeball, congestive edema of the bulbar conjunctiva, and limited rotation. Orbital CT scans often show a blurred contour of extraocular muscles (EOMs) and surrounding immunoreactive lesion. The main manifestations are the enlargement of EOMs including the muscle abdomen and tendons. Eyelid ultrasound can also be used for assisted examination, where CDFI shows that the blood flow signal within the lesion is not abundant.[8]

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4.4 Intermuscular hemangiomas

The structures of intramuscular hemangiomas in EOMs resemble cavernous hemangiomas without a capsule, and consist of abundant thin-walled sinusoids. Intermuscular hemangiomas distribute between muscle fibers, which results in thickening of the muscles and decreased globe mobility. The MRI examination often shows a hyperintense high edge, and the lesion is with clear, enhanced boundaries after enhancement.[9]

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4.5 Lymphoma

The incidence of orbital lymphoma is low, accounting from 6% to 8% of orbital tumors, yet there are some cases involving EOMs. Orbital lymphoma involving EOMs is more common unilaterally and may infiltrate multiple EOMs.[10] Pathologically, lymphomas are composed of undifferentiated cells and lymphoid cells, that lack a fibrous matrix. Orbital lymphomas often infiltrate the eyelids and sclera.

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5 Treatment and prognosis

Orbital GCTs are usually benign and most can be completely removed or partially resected with surgical treatment. The chance of postoperative recurrence is low and some spontaneously regress after partial resection.[4,11] However, in patients with preoperative diplopia, diplopia may persiste after surgery. Cases of relapsed and systemic metastases of malignant GCTs are rare.

In conclusion, ophthalmologists should be aware that when a patient's visual acuity is normal when looking forward but severely low when gazing upward, it may be a sign of a GCT of the inferior rectus muscle.

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Author contributions

LGY designed the study and drafted the manuscript. LC, PH, and BF collected and interpreted the data. LGY performed the operation. All authors read and approved the final manuscript.

Supervision: Pei He, Bin Fan, Guang-Yu Li.

Writing – original draft: Lin Che.

Writing – review & editing: Lin Che.

Lin Che orcid: 0000-0001-5436-7623.

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References

[1]. Lacey B, Chang W, Rootman J. Nonthyroid causes of extraocular muscle disease. Surv Ophthalmol 1999;44:187–213.
[2]. Rickert RR, Larkey IG, Kantor EB. Granular-cell tumors (myoblastomas) of the anal region. Dis Colon Rectum 1978;21:413.
[3]. Damjanov Ivan. Enzinger and Weiss's soft tissue tumors, 5th edition. Shock 2008;30:
[4]. Li XF, Qian J, Yuan YF, et al. Orbital granular cell tumours: clinical and pathologic characteristics of six cases and literature review. Eye (Lond) 2016;30:529–37.
[5]. Dabbs CB, Kline LB. Big muscles and big nerves. Surv Ophthalmol 1997;42:247–54.
[6]. Wiener ES. Head and neck rhabdomyosarcoma. Semin Pediatr Surg 1994;3:203–6.
[7]. Mcclintic SM, Kim HJ, Vagefi MR, et al. Parameningeal alveolar rhabdomyosarcoma with metastases to all the extraocular muscles. Clin Exp Ophthalmol 2014;42:202–4.
[8]. McKinney AM, Short J, Lucato L, et al. Inflammatory myofibroblastic tumor of the orbit with associated enhancement of the meninges and multiple cranial nerves. AJNR Am J Neuroradiol 2006;27:2217–20.
[9]. Wang R, Chen M, Cai K, et al. MR imaging differential diagnosis of soft tissue occupying lesions in extremities. Chin J Med Imaging Technol 2004;20:755–7.
[10]. Gerbino G, Boffano P, Benech R, et al. Orbital lymphomas: clinical and radiological features. J Craniomaxillofac Surg 2014;42:508–12.
[11]. McNab AA, Daniel SE. Granular cell tumours of the orbit. Aust N Z J Ophthalmol 1991;19:21–7.
Keywords:

EOMs; GCTs

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