Angioleiomyoma

Angioleiomyoma also known as angiomyoma or vascular leiomyoma is a benign pericytic or perivascular soft tissue tumor.  

Epidemiology

Angioleimyomas are rare and have been observed in a wide age range with a peak in the 4th to 6th decades of life. Generally, women are more commonly affected ^1-4. They account for up to 5% of all benign soft tissue neoplasms ³.

Clinical presentation

The usual presentation is a firm slow-growing nodule, more than half of the tumors are associated with pain ^1-3.  

Pathology

Angioleiomyomas typically originate in the skin and subcutaneous tissues and mainly constitute well-differentiated perivascular smooth muscle cells aligned around multiple variably-sized vascular channels ¹. There are descriptions of a fibrous pseudocapsule ^2,5.

Etiology

There is no clear established etiology for angioleimyomas. Venous stasis and minor trauma have been proposed as potential causative factors ¹.

Location

Angioleiomyomas are most frequently found in the subcutaneous tissues and dermis and rarely in the deep soft tissues of the following locations ^1-5:

• lower and upper extremities
• head and neck region
• trunk

Macroscopic appearance

Macroscopically angioleiomyomas are usually circumscribed solitary relatively small masses < 3 cm at the time of their presentation and feature a grayish-white to brown appearance ^1,4.  

Microscopic appearance

There are three different histological subtypes of angioleiomyomas subject to their vascular morphology (solid, venous and cavernous) with the following features ¹:

• fascicles of bland, well-differentiated smooth muscle cells
• interposed vascular channels of a variable caliper
• possible myopericytoma-like elements
• might show adipocytic metaplasia, prominent hyalinization or uncommonly calcification

The subtypes do not seem to have any clinical significance.

Immunophenotype

Immunohistochemistry stains are usually positive for smooth muscle actin, calponin and h-caldesmon as well as variably positive for desmin ¹.

Radiographic features

Imaging findings are generally non-specific ^2,3:

• usually well-defined, oval, lobulated or round masses
• expansile growth
• sometimes with cortical scalloping if adjacent to bony structures

Ultrasound

On ultrasound angioleiomyomas have been described to display the following characteristics ^3,4:

• echotexture: homogeneous in the majority of cases, heterogeneous in about a fourth
• usually hypoechoic or hypoechoic and isoechoic
• might show hypoechoic protrusions at the ends of the mass
• posterior acoustic enhancement
• vascular flow signal on color Doppler
• no septations

CT

CT will probably show a well-defined and otherwise unspecific cutaneous or subcutaneous soft tissue density mass. There might be calcifications.

MRI

In addition to the general imaging features a peripheral low-signal intensity rim corresponding to a fibrous pseudocapsule with adjacent vascular structures have been described on MRI in addition to the following signal characteristics ^2-5:

• T1: isointense or hyperintense to muscle
• T2: heterogeneous and slightly hyperintense to muscle
• T1 C+ (Gd): homogenous to heterogeneous enhancement, rarely only peripheral

Radiology report

The radiological report should include a description of the following:

• form, location and size
• tumor margins and transition zone
• distance from the muscular fascia
• contact to bones or neurovascular structures

Treatment and prognosis

Management is primarily surgical excision. Angioleiomyomas are benign and recurrence is rare ^1-5.

Differential diagnosis

Conditions that can mimic the presentation and/or appearance of angioleiomyomas include ^2-4:

• giant cell tumor
• peripheral nerve sheath tumor
• hemangioma
• glomus tumor
• nodular fasciitis
• angiolipoma
• synovial sarcoma