Intramuscular hemangioma - suboccipital neck

Case contributed by Francis Fortin

Presentation

Left posterior cervical mass noted a few months prior, felt to be slowly increasing in size. Mild functional impairment but no significant pain. On physical exam, firm palpable mass without a palpable thrill or warmth.

Patient Data

Age: 25 years
Gender: Female

Highly vascularized mass in upper portion of the left cervical paravertebral muscles with mild bony remodeling of the left occipital bone suggesting a slowly evolving lesion.

Selected series from a diagnostic angiography shows an enlarged left occipital artery feeding the mass, with only very mild early venous drainage, which makes an arteriovenous malformation unlikely. To a lesser extent, vertebral artery and thyrocervical artery branch collaterals supply the mass (not shown).

Discrete intramuscular mass with internal arterial flow on Doppler which is moderately resistive.

Bilobed intramuscular mass in the upper cervical left paraspinal muscles. The mass is mostly well-defined and confined to muscle, but at its mid-anterior portion, its margins are less well defined and come into close contact with the posterior epidural space between the occiput and C1.

Signal is high on T2WI, intermediate on T1WI, with avid homogenous enhancement and numerous serpiginous flow voids.

Percutaneous biopsy was performed at an outside hospital, with a report suggesting an intramuscular hemangioma.

After multidisciplinary consensus in a vascular anomalies clinic, elective partial surgery was planned with resection of the superficial part of the lesion to help alleviate symptoms and obtain a better biopsy specimen. Preoperative embolization was performed.

Preoperative embolization

dsa

Selected images from preoperative endovascular embolization of the mass via the dominant left occipital artery with microcatheters, initially using Onyx™-18 and subsequently 500-700 μm microspheres.

SURGICAL PATHOLOGY REPORT (translated from French)

Type of specimen: cervico-occipital vascular lesion.

Clinical information: cervical and occipital lesion of vascular appearance a priori progressive evolution, invading the soft tissues, compatible with a PTEN hamartoma, an intramuscular capillary-type hemangioma or a hemangiopericytoma. Biopsy is in favor of a hemangioma (outside hospital examination). Indication for removal after embolization.

MACROSCOPIC EXAMINATION

The specimen measures 3 x 4 x 5.5 cm with a skin fragment on the surface measuring 8 x 4 cm. The boundaries were inked in green. After fixation in buffered formalin, staged specimens were taken for samples for examination in 5 blocks (block 1: tips, blocks 2, 3 and 4, 5: staged specimens).

MICROSCOPIC EXAMINATION

The lesion is poorly limited, constituted by an intramuscular vascular proliferation of capillaries, vessels of larger caliber and some lymphatic vessels (D2-40+). Locally, lobules of adipose tissue are also seen. There are signs of striated muscle damage within the lesion with dystrophic aspect of the muscle fibers. There is no cytonuclear atypia. The excision passes within the lesion in depth. On the surface, smooth muscle tissue, hypodermis, dermis and epidermis of normal histological appearance. In the periphery of the lesion, vessels containing an amorphous eosinophilic substance are observed (embolization).

Immunohistochemistry: Glut-1 -, HHV8 -, Ki67<1%.

CONCLUSIONS:

Intramuscular cervical hemangioma without suspicious character.

Excision passing within the lesion in depth.

1 year post-treatment

ultrasound

The residual lesion is much less vascularized one year later, attributed to the preoperative embolization.

1 year post-treatment

mri

The superficial part of the mass has been resected, without recurrence. The deeper portion of the mass is rather unchanged in size. There are much less flow voids, attributed to the preoperative embolization.

Case Discussion

Intramuscular hemangiomas are rare vascular anomalies, currently (at the time of writing in 2022) in the "Provisionally unclassified vascular anomalies" of the ISSVA classification of vascular anomalies. They should not be confused with infantile hemangiomas which are much more common and stain GLUT-1 positive, nor with intramuscular venous malformations which are sometimes referred to inappropriately as "hemangiomas".

Growth is generally proportional to somatic growth, or very slowly progressive over time. Some cases can mimic arteriovenous malformations (AVMs) on Doppler because of large arterialized vessels, but resistive index is generally high and there is usually no significant arteriovenous shunting, in addition to there always being a discrete mass which should not be seen in AVMs.

Case courtesy of Pr Laurent Guibaud.

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