Intramuscular Hemangioma of the Sternocleidomastoid: A Rare Tumor in an Unusual Location

Introduction

Hemangiomas are endothelium-derived neoplasms composed of vascular spaces that emerge from endothelial cells. During the first year of life, hemangiomas are frequently discovered in infants, and these lesions tend to achieve involution as they grow. ¹ A unique type of hemangioma is known as intramuscular hemangioma (IMH). It is a benign vascular lesion found in the skeletal muscles of the trunk, upper and lower extremities, and to a lesser extent, in the head and neck region.^2,3 Intramuscular hemangiomas account for less than 1% of all hemangiomas. ⁴ Only 15% percent of intramuscular hemangiomas occur in the head and neck regions. Masseter and trapezius muscles are frequently mentioned in the reports, while IMH of the mylohyoid and sternocleidomastoid (SCM) muscles are rare, along with other head and neck muscles.^5,6 Intramuscular hemangiomas typically present as painless masses that develop slowly with distinct boundaries. ⁷ Radiological evaluations using magnetic resonance imaging (MRI) and computed tomography (CT) are critical for identifying IMH. ⁸ This case report described a rare case of sternocleidomastoid IMH managed with preoperative angioembolization followed by complete surgical excision. A review of the literature for similar cases of SCM IMH was also performed and discussed.

Case Report

We present a 25-year-old man with an insignificant medical and surgical history, who was referred from primary health care to our ENT head and neck clinic for the evaluation of a neck mass. He complained of a left neck mass that started 2 years prior and was stable in size. The complaint was not preceded by a history of infection or trauma. There were no other symptoms, and the patient denied pain, alterations in size, skin changes, night sweats, weight loss, loss of appetite, or fever. Examination revealed a triangular mass in the left posterior neck over the upper third of the sternocleidomastoid muscle area. The lesion measuring 3 cm × 4 cm, was firm and non-tender, with no skin changes. No enlarged cervical lymph nodes were palpated. The rest of the ENT examination, along with the cranial nerves and fiberoptic flexible nasopharyngeal scope, were unremarkable. Blood results were also unremarkable. Contrast-enhanced computed tomography showed a slightly hyperdense soft tissue mass in the upper one-third of the sternocleidomastoid muscle, deep into the skin (Figure 1A). Head and neck MRI demonstrates a well-delineated soft tissue lesion with query infiltration into the surrounding SCM. The lesion was isointense in the cervical muscles on the T1 sequence (Figure 1B) and hyperintense on the T2 sequence (Figure 1C). The post-gadolinium study showed a strong enhancement with some heterogeneity and persistence of signal voids of the intralesional vessels with the impression of soft tissue hemangioma (Figure 1D). The selected management option of surgery preceded by angioembolization was explained to the patient, and consent was obtained. Angiography revealed a well-defined left posterior paravertebral slow-flow cervical venous malformation supplied mainly by the left occipital artery. One day prior to surgery, embolization through angiography was performed using onyx, with an uneventful post-embolization course. The patient underwent surgery the next day with a horizontal neck incision following the skin lines over the mass. The mass was found immediately after the thinned subcutaneous tissue was dissected from the surrounding tissues. The lesion was hypervascularized with multiple perilesional vessels, infiltrating the surrounding SCM with a cut-off muscle that was removed along with the mass to ensure complete excision and decrease the chance of recurrence (Figure 2). The intraoperative bleeding was mild and reasonable. A medium-sized drain was inserted before closure and maintained under negative pressure. The patient recovered smoothly and was discharged on postoperative day (POD) one after drain removal. Histopathological examination of the mass showed vascular proliferation within the skeletal muscles and fatty tissues with an abundance of capillaries, consistent with capillary type intramuscular hemangioma (Figure 3). The patient was followed-up in the clinic. The wound healed without problems and there was no recurrence 3 months after surgery. Preoperative angioembolization contributed to surgical success by decreasing the operation time and blood loss, and facilitating dissection and excision of the mass to decrease the chances of recurrence.

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Figure 1.

(A) Contrast-enhanced CT (axial cut) demonstrating slightly hyperdense soft tissue mass in the upper one-third of the left SCM. (B) MRI T1-weighted image (axial cut) demonstrating isointense mass in the left SCM. (C) MRI T2-weighted image (axial cut) demonstrating hyperintense mass in the left SCM. (D) Gadolinium-enhanced MRI (axial cut) demonstrating strong enhancement with some heterogeneity in the left SCM.

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Figure 2.

Intraoperative excised mass from the left sternocleidomastoid muscle measuring 3 x 4 centimeters.

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Figure 3.

(A) A low power of H&E-stained section showing vascular proliferation between skeletal muscle fibers. (B) High magnification showing blood vessels proliferation between muscle fibers, some are containing red blood cells. (C) Immunohistochemical stain for CD31 antibody highlighting the endothelial cells of numerous blood vessels.

Discussion

Neck masses frequently present a diagnostic challenge with a wide variety of differential diagnoses including infection, inflammation, or neoplasia. In certain cases, when the diagnosis remains uncertain after radiological and pathological investigations, an excisional biopsy is required. Although certain lesions can be safely observed, others require further attention and investigation, particularly when the diagnosis is unclear or a neoplastic process is considered. ⁹ Intramuscular hemangioma (IMH) is a benign vascular tumor that accounts for less than 1% of all hemangiomas. It typically develops in the chest wall and lower extremities, while uncommon to be found in the head and neck region.^10,11 IMH was first described by Liston in 1843 as a benign congenital tumor restricted to lower extremities muscles. ¹² These tumors are more frequently diagnosed in adolescents and young adults, with no sex predilection. ¹⁰ Although the cause of IMH is not well understood, it is believed to be a congenital tumor that develops from embryonic remnants, same as congenital arteriovenous malformation.^13,14 Pathologically, Hemangiomas are classified into 3 types: small vessel or capillary, large vessel or cavernous, and mixed. When a lesion encompasses a combination of different vessel types, it is known as a mixed-type hemangioma. ¹⁵ The most prevalent types of intramuscular haemangiomas in the head and neck region are capillary type hemangiomas, which encompass 68% of all cases, followed by cavernous and mixed hemangiomas, which constitute 19% and 5% of all IMH in the head and neck region, respectively. ¹⁵ In the literature, 12 case reports, including the present case of IMH involving the sternocleidomastoid (SCM) muscle, have been reported. Two of the 12 case reports lacked clinical information; thus, they were excluded. The average age of the 10 included cases was 40.8 ± 17.1 years (Table 1).^{6,9,16 -22} However, of the reported 10 cases of IMH in the SCM, 6 were cavernous type (Table 1).

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Table 1.

All Published Case Reports of Intramuscular Hemangioma in the Sternocleidomastoid.

Author name/year	Age/gender	clinical presentation	Investigation	Histology	Preoperative angioembolization	Excision	Blood loss	Recurrence
Jan et al (1990)	29/F	Neck mass for 6 mo rapidly progressive associated with pain.	FNA: blood. Carotid arteriography with digital subtraction studies	mixed type hemangioma	No	Wide excision involving the muscle	Minimal	No
Broniatowski et al (1993)	27/M	Neck mass for 3 mo Painless with sudden onset	No investigation	arteriovenous hemangioma	No	Wide excision involving the muscle	Minimal	No
Zhan et al (1997)	55/M	Neck mass for 14 y, gradually increasing in size with hoarseness	FNA: inconclusive Incisional biopsy: inconclusive MRI: non-homogeneous mass carotid angiogram: common carotid artery displacement	Giant cavernous type hemangioma	No	enucleation	N/A	N/A
Chaudhary et al (1998)	15/M	Neck swelling for 1.5 y, painless gradually increasing in size	FNA: inconclusive CT: moderately enhancing mass with poorly defined margins beneath the muscle	cavernous type hemangioma	No	Wide excision involving the muscle	Profuse bleeding	N/A
Lee et al (2005)	42/M	Painless Neck mass	FNA: blood CT: ill- defined, well-enhancing mass	capillary type hemangioma	No	Wide excision involving the muscle	N/A	No
Moumoulidis et al (2007)	71/F	Neck mass for 2 y, painless gradually increasing in size	FNA: blood Ultrasound-guided biopsy: mixed cystic and solid lesion CT: well defined swelling, with faint enhancement of a nodular pattern	cavernous type hemangioma	No	Wide excision involving the muscle	N/A	No
Ferri et al (2007)	32/F	Neck mass for 6 mo, painless recently increasing in size	CT: non-homogeneous mass MRI: diffusely enhancing, well- defined soft tissue lesion Angiography: no obvious feeder vessels	cavernous type hemangioma	No	Wide excision involving the muscle	N/A	No
Pistor et al (2011)	52/M	Painless Neck mass for 5 y	MRI: homogenous mass	cavernous type hemangioma	No	Wide excision involving the muscle	Profuse bleeding	No
Abou-Al-Shaar et al (2018)	60/F	Neck mass for 9 mo, stable in size associated with pain, dysphagia and hoarseness	FNA: inconclusive Open biopsy: cavernous hemangioma CT and MRI: heterogeneously enhancing lesion with small intracranial component digital subtraction angiography: stenosed jugular bulb with dominant contralateral venous outflow	cavernous type hemangioma	No	Wide excision involving the muscle	N/A	No
Present case	25/M	Neck mass for 5 y gradually progressing in size	CT: hyperdense soft tissue MRI: well-delineated soft tissue heterogeneous lesion Angiography: well-defined left posterior paravertebral slow flow cervical venous malformation	capillary type hemangioma	Yes	Wide excision involving the muscle	Mild	No

Abbreviations: CT, computed tomography; FNA, fine-needle aspiration; MRI, magnetic resonance imaging.

IMH usually presents as a well-defined, localized, soft, mobile, fluctuating mass. ¹⁶ Diagnosis of IMH requires thorough history taking and physical examination and is usually depicted by radiological investigations. MRI has been reported to be superior to CT for identifying intramuscular hemangiomas, defining their extent, and distinguishing between normal muscles and intramuscular hemangiomas. ¹¹ IMH MRI typically demonstrates a hypointense signal on T1-weighted images and a hyperintense signal with well-defined borders that can be distinguished from nearby normal muscles on T2-weighted images. ¹⁷ In most cases, fine-needle aspiration (FNA) tends to reveal only blood and is non-diagnostic. ¹¹ Complete surgical excision is considered the best treatment choice for IMH because it is the only treatment option that is able to definitively exclude malignant transformation. ¹¹ The tumor infiltrative ability of IMH necessitates the removal of normal muscles considerably beyond the gross margins of the tumor to avoid local recurrence of the tumor. ¹¹ Prior to surgical intervention, angiography or a vascular study is beneficial, as it can provide clear details about the nature of the tumor, the blood supply, and the need for preoperative embolization. ¹¹ Although preoperative angioembolization is helpful for reducing intraoperative bleeding and the associated morbidity, none of the reported cases of SCM IMH used preoperative angioembolization before surgery.^11,18,19 Conversely, several cases of IMH in the head and neck region have been reported using angioembolization preoperatively. Broniatowski described a case of capillary-type IMH involving masseter muscle managed with preoperative angioembolization to control bleeding. ²⁰ Rossiter et al. described a case of IMH of the strap muscle of a capillary that was fed by the superior thyroid artery managed by angioembolization preoperative to reduce intraoperative hemorrhage with no subsequent recurrence. ¹¹ Garefis et al. reported a case of scalene muscle IMH fed by the branches of the costocervical and thyrocervical trunks that underwent angioembolization preoperative to control blood loss. ²¹ Aloyouny et al presented a case of zygomaticus muscle capillary-type IMH and suggested that hemangiomas with no identifiable feeders could be managed with primary excision without preoperative embolization. ⁸ Additionally, Welsh et al and Rossiter et al. recommended that in cases of small muscle hemangioma or small-caliber feeding vessels, angioembolization is not indicated, and complete surgical excision is the best treatment.^11,22

Conclusion

Complete surgical excision remains the treatment of choice for IMH. Preoperative angioembolization contributes to surgical success by reducing morbidity, facilitating complete excision, and decreasing the risk of recurrence.