Venous malformation of the sternomastoid muscle (2006)

Venous malformations of skeletal muscle are rare, making up <1% of all vascular malformations.1 Liston2 reported the first description of an intramuscular vascular malformation in 1843. Only 13.5% of intramuscular vascular lesions have been reported in the head and neck.3 The entity often has been called an intramuscular hemangioma and occasionally is called a giant hemangioma. These lesions appear and behave more like intramuscular venous malformations on examination, radiographs, and histologic specimens. A 4-year-old girl presented to the Pediatric Otolaryngology Clinic at Johns Hopkins Hospital with a several-month history of a nontender, left neck mass. Computed tomography of the neck with and without intravenous contrast revealed a solid mass with calcifications medial to the sternomastoid muscle but lateral to the great vessels. Fineneedle aspiration revealed bloody fluid and no abnormal cells. Magnetic resonance imaging (MRI) suggested the diagnosis of vascular malformation involving the sternomastoid muscle. The patient was asymptomatic, and her family chose to defer intervention. Three years later, this child presented with slight enlargement of the neck swelling. Clinically, the 5 × 3 cm soft mass was localized to the left neck centered about the middle to upper portion of the sternomastoid muscle. At age 10 years, the mass swelled abruptly, and the patient returned for evaluation. She had no respiratory embarrassment, dysphagia, trismus, or shoulder weakness. She was treated with antibiotics with resolution of the acute swelling, but the mass remained large. MRI at this time showed an inhomogenous enhancement similar to that seen previously. Excision was recommended. When she returned at age 12 years, the mass filled the entire left neck extending to the midline. MRI-MR angiography (MRA) showed a very large mass within the left sternomastoid muscle, extending from the mandible to the supraclavicular fossa (Fig. 1). It did not enter the mediastinum or chest. It compressed the jugular vein and displaced the carotid artery medially. On MRI, it was T2 hyperintense and T1 isointense. It showed a heterogenous pattern of enhancement after contrast administration. MRA showed no obvious feeder vessels. Endovascular intervention or direct sclerosis was considered, but surgical excision was recommended. Hyperintense mass within the left sternomastoid muscle (T2-weighted MRI). The patient underwent transcervical surgical resection of the mass without complication. The vascular mass consisted predominantly of venous channels and was enveloped by attenuated sternomastoid muscle. It was completely excised, preserving most of the sternomastoid and preserving the spinal accessory nerve. Histologic evaluation revealed medium-sized and thin-walled channels that were lined with a flattened endothelial layer and surrounded by a poorly developed and variably evident smooth muscle sheath (Fig 2), consistent with a venous malformation. The patient is without signs of recurrence 10 months after surgery. Medium-sized, thin-walled vascular channels are lined with a flattened endothelial layer, which in turn are surrounded by a poorly developed and variably evident smooth muscle sheath that extends between muscle fascicles (hematoxylin and eosin, X320). A wide variety of classification schemes have been used to describe vascular lesions in general, and intramuscular venous malformations are no different. Liston2 called his entity an “erectile tumor,” whereas most literature thereafter has regarded these lesions as hemangiomas, most commonly calling them intramuscular hemangiomas. Current clinical, histologic, and biologic evidence would argue that these lesions are actually venous malformations of skeletal muscle.4 Early categorization of these lesions derived from the work of Allen and Enzinger in 1972.5 They based their classification on vessel size, separating all lesions into 3 categories. Small-vessel or capillary hemangiomas made up 68% of lesions in the head and neck. Large-vessel or cavernous hemangiomas made up 19%, whereas a final, 3rd category included lesions of mixed vessel size making up the balance. Edgerton6 introduced a clinical classification in 1976 that was based on the natural history of such lesions. Five types of so-called hemangiomas were described, including neonatal stainings (type I); intradermal capillary hemangiomas (type II); juvenile hemangiomas (type III), which included capillary cavernous hemangiomas and thus venous malformations; arteriovenous fistulae (type IV); and finally cirsoid angiomas (type V). Edgerton stressed that some of these hemangiomas remained essentially unchanged if untreated, whereas others resolved spontaneously. In 1982, Mulliken and Glowacki7 classified all vascular lesions according to biology based on endothelial characteritics. They noted the crucial distinction between true hemangiomas and vascular malformations, stating that hemangiomas are proliferative lesions characterized by increased endothelial cell turnover. They appear at birth, grow rapidly, then involute over the years. Malformations, on the other hand, appear to be errors in morphogenesis populated by a stable, mature vascular endothelium. Malformations are present at birth as well (although not always clinically obvious), grow commensurately with the child, and of note, do not involute. Vascular malformations are classified into subtypes on the basis of the constituent vessels. Capillary, venous, arterial, lymphatic, and combined forms are noted. Histologically, they have a normal endothelial population that is not hyperplastic. This cell population has a normal turnover rate, thus helping explain the ineffectiveness of radiation, chemotherapy, and steroids to cure. Lesions can, however, undergo rapid growth if infection, hormones, or trauma affect them. In general, surgical resection is curative, whereas sclerosis, embolization, and laser obliteration may work for some lesions. Our patient's lesion showed a morphologically stable-appearing endothelium, which lined vascular spaces of varying caliber, which in turn enclosed a thickened wall composed of attenuated and disorganized muscular elements, consistent with the diagnosis of venous malformation. It is difficult to establish the exact number of venous malformations of skeletal muscle that have been reported in the literature. In 1957, Scott3 gathered all cases of “hemangiomata of skeletal muscle” to date (all locations). Of these, 5 were recorded as arising in the sternomastoid muscle (1.4%). From 1957 onward, there have been numerous case reports of intramuscular hemangioma of the head and neck in virtually every muscle. The masseter has been quoted as the most frequently affected, followed by the temporalis.4 8 Including this case, there are now 7 cases involving the sternomastoid muscle that are well documented in the modern medical literature. Physical examination should be exercised carefully to determine the location and extent of the mass. The ability to increase venous pressure by recumbency, Valsalva maneuver, or jugular vein compression to make the tumor more obvious has been called the turkey wattle sign. 9 It is a useful diagnostic sign if positive. Pulsations, bruits, and thrills should be investigated and indicate the possible presence of a prominent feeding vessel. When a vascular malformation is suspected, workup should include an MRI with T1- and T2-weighted images with and without gadolinium. In general, MRI shows intermediate or slightly high signal intensity on T1-weighted images, with extremely bright signal on T2-weighted images.10 Stagnant blood located in the larger vessels of these lesions produces this effect because of the increased presence of free water. As compared with other vascular malformations, venous malformations rarely have high-flow vessels or feeder vessels and thus lack the signal voids produced by such entities. Venous malformations often contain phleboliths (calcifications), though, which are seen as a signal void on MRI and an opaque stone on CT scan. Surgical excision was the treatment for all reported cases of sternomastoid intramuscular lesions. Steroids, chemotherapy, and radiotherapy are not effective. Other therapies discussed in the literature include duplex-guided sclerotherapy with foam injection and angiographic embolization. Recurrence is normally caused by incomplete excision. Venous malformations of the sternomastoid muscle are rare. Clinical and histologic evidence suggests these lesions are vascular malformations rather than intramuscular hemangiomas. Surgical excision is recommended after evaluation with MRI–MRA.