Temporal Muscle Cavernous Hemangioma: A Case Report and Literature Review

Hemangiomas are nonmalignant vascular lesions commonly seen in both the skin and mucosa that rarely occur in skeletal muscles. According to the type of vessel, a hemangioma can be differentiated into capillary, cavernous, or mixed types. The following report describes a case of temporalis muscle hemangioma in a 45-year-old female who presented with painful swelling in the left outer orbital wall, which had been growing in size over the past 12 months. CT scan and MRI revealed a well-demarcated lesion in the temporalis muscle measuring 10 mm × 13 mm × 15 mm. Surgical resection of the lesion was performed, allowing a definitive diagnosis of cavernous hemangioma to be made histologically. As radiological images are mainly inadequate for definitively diagnosing these lesions, surgical intervention is usually required. The recurrence rate differs among the three subtypes; thus, clinical follow-up and radiological imaging as needed are recommended.


Introduction
Hemangiomas are benign vascular lesions that are classified based on the size of the involved vessels into cavernous (large vessel), capillary (small vessel), and mixed hemangiomas [1,2]. Approximately 0.8% of all hemangiomas are considered intramuscular and are frequently found in the trunk and extremities due to the presence of the large muscles in these regions [3]. Head and neck hemangiomas account for approximately 14% of all hemangiomas, most commonly occurring in the masseters, followed by the trapezius muscles, and very rarely in the temporalis muscle [4]. Unsurprisingly, only 33 cases reported in international literature involve intramuscular hemangioma in the temporalis muscle. Intramuscular hemangiomas usually manifest with slow growth, obvious margins, and painless intramuscular masses, while the size and number can vary considerably. Between 15-25% are also characterized by phlebolith formation, a calcified thrombus [5]. The following report describes a case of intramuscular cavernous hemangioma in the temporalis muscle, followed by a review of the pertinent literature.

Case Presentation
A 45-year-old female was admitted to the Neurosurgery Department in King Abdulaziz Medical City, Riyadh, Saudi Arabia. She had a history of painful left orbital swelling on the outer wall that had been progressively increasing in size for a year. She denied any history of trauma, surgery, or visual symptoms. The physical and neurological examinations were unremarkable, with the exception of a smooth and immobile swelling in the outer wall of the left orbit that measured approximately 1.5 cm in diameter and was tender on palpation. No overlying redness or warmth of the skin or any signs or symptoms of inflammation were observed. Additionally, no pulsation or bruit over the lesion was noted. Magnetic resonance imaging (MRI) was performed, revealing a slightly lobulated deep subcutaneous lesion measuring 10 mm × 13 mm × 15 mm in the lateral side of the temporalis muscle at the same level of the left orbit. T1-weighted imaging (T1-WI) exhibited a low signal intensity (Figure 1), while hyperintensity was revealed on T2-WI images ( Figures  2, 3).   The arrow shows the identified lesion with no calcification

FIGURE 6: Computed Tomography Scan, axial view
The arrow shows the identified lesion The patient was taken to the operating room for surgery under general anesthesia. A curvilinear incision was made approximately 1 cm in front of the tragus, and the temporalis muscle and the fascia were dissected by using monopolar electrocautery until a dark-red, soft tissue mass (1.0 cm × 1.0 cm × 0.5 cm) was encountered. Total resection of the lesion with a margin of normal muscle was performed. Histological examination showed a collection of back-to-back cavernous-sized vascular channels. Given the presence of chronic inflammation and epithelioid histiocytes, CD34 and D2-40 immunohistochemistry was performed. The vascular channels were found to be immunopositive for CD34 and immunonegative for D2-40 ( Figure 7).

FIGURE 7: Histopathological Image of the lesion tissue
The postoperative events were uncomplicated, and the patient was discharged home in good condition on the second day. Six months of follow-up did not reveal any local recurrence.

Discussion
Hemangioma is a type of vascular abnormality. Intramuscular hemangioma is a rare benign lesion, as it represents less than 1% of all hemangiomas, 14% of which are found in the head and neck region. The most commonly affected muscles are the masseter (36%) and trapezius (24%) [6], while hemangiomas of the temporalis muscles are extremely rare, as suggested by the limited number (only 33) of cases reported to date in international literature. In 1843, intramuscular hemangioma was primarily reported by Liston [7]. Allen and Enzinger established the most comprehensive classification of intramuscular hemangiomas [1], whereas Enzinger and Weiss subsequently identified three subtypes based on histological findings, denoted as small, large, and mixed-type vascular hemangiomas [8]. Capillary hemangiomas are considered to account for 68% of all intramuscular hemangiomas that involve small capillary-sized vessels, followed by cavernous hemangiomas (with an incidence of 26%), which are distinguished by thin-walled and cystic blood spaces, and finally, venous or mixed-type hemangiomas (6%) that comprise widened veins of irregular thickness inside loose fatty fibrous stroma [9].
The etiology behind these lesions is not known; however, recurrent trauma or hormonal changes can cause the lesion to grow as a result of the proliferation of embryonic vascular tissue [10]. Clinically, in 98% of cases, intramuscular hemangioma presents as a slowly growing mass with definite margins and pain (in 30−60% of the cases) [1,8]. It is mobile and does not demonstrate any vascular signs, such as skin discoloration or pulsation. The most common differential diagnoses include lipoma, lymphoma, dermoid cyst, and temporal arteritis [11,12].
Intramuscular hemangioma is diagnosed preoperatively in only < 8% of cases because of its low incidence and lack of specific symptoms [13,14]; hence, imaging studies play a significant role in the diagnosis. Computed tomography is useful in the determination of lesion size and shape while facilitating the assessment of the surrounding tissues. However, for identifying the nature of the lesion, MRI is mandatory. On T1-WI images, hemangiomas show hypointensity or isointensity with a fat-free lesion, which can exclude angiolipoma. On T2-WI images, the lesion is characterized by hyperintensity and high fluid content. The lesion also demonstrates an enhancement after administration of contrast medium, whereby good vascularization would exclude lymphoma as a potential diagnosis [15]. MRI can also show definitive findings radiologically that favor hemangioma, specifically a hyperintense signal on T2-WI imaging; the presence of fibrosis, thrombus, and/or deposition of hemosiderin; and on histological assessment, endothelial-lined vascular channels are separated by fibrous and fatty linear tissue in considerable lesions measuring 2 cm in diameter [16]. Arteriography may be helpful in identifying the lesion's feeding vessels and whether these vessels need to be embolized before surgery [17,18].
In the international literature, only 33 cases of temporalis muscle hemangioma have been reported to date ( Table 1). All reported cases are characterized by hyperintensity on T2-WI imaging, while T1-WI imaging shows either isointense or hypointense signals. None of the cases involved bony erosion or invasion of the surrounding tissue, but some showed calcification of the lesion on CT. The most common type of hemangioma in the temporalis muscle is cavernous (27/33), followed by capillary (only four cases). The mean age of patients with temporalis muscle hemangioma is 37.76 ± 18.73 years, with a slight male preponderance (18/33). According to the literature review, in 31 of these cases, surgical resection of the lesion was the treatment of choice, while only Heckl et al. and Gadhia et al. followed the patients clinically and radiologically [15,19]. Multiple factors determine if surgical resection is indicated, including the age of the patient, the extent of bleeding, lesion size and location, the level of pain, the depth of invasion, the rate of growth, the degree of cosmetic deformity, and malignant susceptibility [11,13,20]. Local recurrence of the intramuscular hemangioma is associated primarily with incomplete resection, while the rate of local recurrence for completely resected lesions differs among the three pathohistological subtypes, with 28% for capillary, 20% for cavernous, and 9% for mixed-type hemangioma [17]. None of the reported cases of temporalis muscle hemangioma indicated any local recurrence. However, clinical follow-up and radiological images (if needed) are recommended to detect any future recurrence.

Conclusions
Hemangiomas are nonmalignant vascular lesions that are uncommonly found in the temporalis muscle. Based on histological findings, they are classified into three subtypes. As radiological images are mainly inadequate for a definitive diagnosis of these lesions, surgical intervention with resection is the treatment of choice in most cases. The recurrence rate of intramuscular hemangioma differs among the three subtypes. Clinical and radiological follow-up and radiological images as needed are recommended.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.