Intramuscular hemangioma of the medial rectus as a rare cause of extraocular muscle enlargement: Report and review of literature
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.258033
Source of Support: None, Conflict of Interest: None
Hemangiomas are benign, non-metastasizing tumors composed of hamartomatous proliferation of blood vessels, most commonly found in cutaneous and mucosal surfaces of infants and children. Those affecting skeletal muscles, also known as intramuscular hemangiomas (IMHs), are rare and represent <1% of all hemangiomas. They have a predilection for muscles of the trunk and extremities, head and neck region being involved only in about 14% of the cases., IMHs affecting the extraocular muscles (EOMs) are extremely rare with only seven cases being reported in the literature till date.,,,,,
A rare case of IMH affecting the medial rectus muscle in an adult male is presented with emphasis on its clinical presentation, differential diagnosis, and treatment modalities. A brief review of literature is also presented.
A 61-year old male patient presented with a history of progressive, painless proptosis of the right eye since 6 months, and blurring of vision associated with binocular diplopia since the last 4 months. There was no associated lacrimation or photophobia. Examination revealed a visual acuity of 6/60 with relative afferent pupillary defect in the right eye and normal Ishihara color plate testing. Hertel exopthalmometry revealed a 6 mm proptosis on the right side. The anterior segment and fundus examination were normal. Systemic clinical examination did not suggest any inflammatory or infectious process.
Magnetic resonance imaging (MRI) of the orbit showed a large, well-defined mass along the medial aspect of right orbit in the extra- as well as intraconal compartment. Medial rectus muscle was not seen separately from the lesion. Posteriorly, the lesion was extending up to the orbital apex encasing the retrobulbar and intracanalicular component of the right optic nerve. On T1-weighted images, the mass was isointense as compared to other EOMs, while it was hyperintense as compared to the subcutaneous fat on T2-weighted images. The tumor showed a diffuse heterogenous enhancement with gadolinium administration [Figure 1]. The adjacent soft tissue appeared normal and there was no bone defect.
The patient underwent an orbitotomy with excision of the tumor and posterior decompression. Intraoperatively, the tumor was infiltrating the medial rectus muscle diffusely as well as the orbital apex fat. The lesion was abutting the optic nerve at the apex and displacing the nerve laterally. Debulking of the tumor was done by sharp and blunt dissection. On gross examination, tumor was purple, firm in consistency, and irregular in shape. Pathologic examination revealed fascicles of skeletal muscle with interspersed numerous small- and medium-sized blood vessels. No typical cavernous-like blood vessels were identified. No features of malignancy were seen. The findings were consistent with the diagnosis of an IMH [Figure 2]. Postoperatively, the patient recovered well without any new neurological deficits.
IMH is a rare entity, predominantly affecting the muscles of the lower extremities, especially the thigh. Mostly seen in the younger population, 80–90% of these tumors are detected before the age of 30 years. Thus, the etiology is thought to be congenital, with a period of dormancy before they start growing in the second/third decade of life. The growth may be triggered by trauma or hormonal factors, although the exact cause is unknown. Based on the predominant vessel type on histopathology, Allen and Enzinger classified them as capillary (most common), cavernous, or mixed small/large vessel types.,
In the head and neck region, IMH most commonly involves the masseter muscle followed by the trapezius. The first case of IMH affecting the EOMs was reported by Christensen et al., in 2002. Since then, a total of seven cases have been published in the literature, as described in [Table 1]. The tumor affected a wide age group, ranging from 3 years to 63 years and both the genders. The predominant symptom was either a gradually progressive, painless unilateral proptosis, or a localized slow growing mass. Most patients had an associated edema of the eyelid/s and diplopia. The visual acuity, however, was unaffected in all except the first case (Christensen et al.,) where it was decreased owing to compression of the optic nerve by the large size of the tumor.,,,,, Similar findings were noted in our case.
MRI of the orbit in cases of IMH shows isointense lesions on T1-weighted images due to stagnant blood in large blood vessels. On T2-weighted images, they are characteristically hyperintense, sharply delineated intramuscular lesions with intra-lesional linear isointense areas, representing fibrofatty septae between the vessels. The combination of stagnant blood and non-vascular tissues in the tumor may produce a typical serpiginous pattern. They show a marked contrast enhancement on gadolinium study owing to their highly vascular nature.,
The differential diagnosis of EOM enlargement includes thyroid ophthalmopathy (most common), metastases, lymphomas, and idiopathic inflammation. Other rare causes include amyloidosis, Trichinella spiralis infestation, cysticercosis, and dermoid cyst. Vascular tumors affecting EOMs are rare, the most common being a carotid-cavernous fistula., In cases of large hemangiomas, the possibility of the tumor burrowing into the EOM may also be considered, in which case the muscle would be thinned out and displaced. This possibility was ruled out in our case as there was fusiform enlargement of the medial rectus muscle and the histopathology showed the typical features of an IMH. Thus, it is difficult to establish a definitive diagnosis of IMHs in the preoperative period and it is only on histopathology that the final diagnosis could be reached.
The tumor is benign, and in contrast to the cutaneous hemangiomas, IMHs never regress spontaneously. Treatment options for IMHs elsewhere in the body include surgical excision, cryotherapy, radiotherapy, injection of sclerosing agents, and corticosteroids. However, the treatment of choice is complete surgical excision with a rim of surrounding healthy tissue as the tumor is infiltrative in nature. In the case of an incomplete excision, the recurrence rate is 9–28%., This approach may be too radical in the extraocular region, leaving the patient with a significant irreversible ocular motility disorder. A few authors have resorted to medical management with systemic corticosteroids. Though corticosteroids reduced edema and proptosis, there was no significant shrinkage of the tumor.,, The response to systemic steroids is often poor in the presence of cavernous elements and encapsulation. The use of intra-lesional steroid injection might lead to significant retrobulbar hemorrhage. A few authors have attempted incisional biopsy of the mass and encountered profuse bleeding, while others have preferred excision of the mass. A radical approach with enucleation was adopted in the first case (Christensen et al.,) owing to the progressive worsening of the symptoms along with the large tumor size. The histopathology in all cases showed striated muscle fibers with interspersed numerous blood vessels of various sizes, thus confirming the diagnosis of IMH.,,,,,
IMHs are rare causes of EOM impairment and must be considered in the differential diagnosis of extraocular muscle enlargement. The preoperative diagnosis is usually difficult to establish. MRI may be of help due to the characteristic imaging findings of the lesion. The most appropriate treatment of IMHs in the extraocular muscles remains elusive due to rarity of this tumor. Corticosteroids being of limited help, complete surgical excision seems a better option in terms of achieving a complete cure.
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[Figure 1], [Figure 2]