Teaching Case

We present an unusual case of a 61-year-old man with a large and slow-growing soft tissue mass in the palmar aspect of the left hand. There was no association with pain or history of trauma. No other known diseases, namely rheumatological diseases.

Magnetic Resonance imaging (MRI) was performed, demonstrating a well-defined 5cm subcutaneous soft tissue mass in the volar aspect of the hand.

It shows predominantly isointense signal compared to skeletal muscle on T1-weighted images (T1-WI) (figure 1) and heterogenous signal on fat-suppressed DP-weighted images (FS DP-WI), with intermingled hyperintense and isointense areas. Several serpentine high signal intensity areas on FS DP-WI were also observed, abutting the periphery of the mass (figure 2).

A well-defined hypointense peripheral rim was seen on both T1-WI and FS DP-WI.

After intravenous administration of paramagnetic contrast, the mass showed strong and heterogeneous enhancement, with hyperintense areas on STIR-WI displaying the greater degree of enhancement on dynamic study (figure 3).

No signs of invasion of the tendons or bone were seen.

Angioleiomyoma is a relatively rare, benign, vascular smooth muscle tumor originating from the tunica media of veins and arteries. They can occur in the dermis, subcutaneous fat or fascia, and can be located anywhere in the body, more frequently in the lower limbs. [1-3]

There is a slight female predominance (male/female ratio: 1.0/1.7), occurring more frequently in the fourth to sixth decades of life. [3]

Angioleiomyomas are usually small, firm, mobile, slow-growing masses. Patients typically report several years of symptoms before presentation, with pain as the most striking clinical feature, reported in 44-60% of patients. [1,4,5]

Ultrasound and, specially, MRI can provide valuable preoperative information. Apart from inherent smooth muscle bundles and blood vessels, these tumors may also contain areas of hyalinization, fat or calcifications, that can be identified by imaging modalities. Radiography and CT images usually show a well-defined and otherwise nonspecific cutaneous or subcutaneous mass, with soft tissue density which may or may not present calcifications or fat. [3]

On ultrasound examination angioleiomyoma demonstrate well-defined margins, oval shape and hypoechoic homogeneous structure with vascularity. [4]

On T1-WI MRI images, these tumors appear either homogeneously or heterogeneously iso-intense to muscle. On T2-WI MRI images they usually exhibit heterogenous linear, serpentine, and branching regions of high signal intensity, corresponding to numerous vessels. Due to these vessel component, such areas generally show strong enhancement, while isointense areas, corresponding to fibrous tissue, are usually non-enhancing.  A peripheral hypointense rim is frequently seen on both T1-WI and T2-WI and corresponds pathologically to a fibrous capsule.  Tortuous vascular structures abutting the mass may also be identified and constitute a clue for the diagnosis. [4, 6, 7]

Preoperative core needle biopsy is often helpful in the diagnosis, but the lesions are usually excised due to associated pain and to obtain definitive diagnosis.  [8]

Simple marginal excision is usually performed as local recurrence after excision is extremely rare. [3]

Angioleiomyoma should be considered in the differential diagnosis of a painful or painless slow-growing superficial mass in the hand or foot. This is particular the case when MRI characteristic feature of T2-WI linear, serpentine or branching regions of hyperintensity within a lesion show strong enhancement.  The identification of tortuous vascular structures abutting the mass also indicates this diagnosis.

Written informed patient consent for publication has been obtained.