A 51-year old male presented to the clinic for consultation of a soft tissue mass of the right lower extremity [Figure 1]. Patient reported an insidious onset of tissue growth over one month’s duration, denying precipitous injury and without pain, ulceration, or similar tissue growth systemically. Plain film [Figure 2] and MRI imaging failed to demonstrate periosteal reaction or associated bony change while MRI [Figures 3-5] revealed a 2.0cm x 2.0cm well-circumscribed soft tissue tumor of the medial ankle with predominant fat signaling concerning for a well-differentiated liposarcoma. Physical examination showed a firm, non-mobile, non-pulsatile mass residing within the subcutaneous tissue anteromedial aspect of the right ankle.

After conference with orthopedic oncology and the provisional diagnosis of fibrosarcoma, definitive surgical excision was performed. A curvilinear incision was planned over the lesion and blunt dissection was carried out to the level of the subcutaneous tissue whereby the tumorous mass was identified. No tourniquet was used so to easily identify the vascular anatomy of the mass while also assuring strict hemostasis within the surgical field in a setting of possible malignancy. A high-frequency ultrasound scalpel was employed to carefully dissect the tumor from the medial ankle including ligation of the saphenous vein which was found to have a direct extension to the tumor along its posterior margin [Figure 6]. At the time of excision, the mass measured 4.0cm x 2.6cm x 2.7cm to the level of fascia tagged with suture to maintain anatomical orientation [Figure 7].

Surgical pathology classified the mass as a rare angioleiomyoma composed of thick fibromuscular capsule and areas of smooth muscle proliferation, no malignancy or cellular atypia was found. The patient’s post-operative course consisted of non-weight bearing for two weeks to prevent bleeding into the tissue defect followed by protected weight bearing in a CAM walker for an additional 4 weeks. Suture removal was performed as scheduled without incisional complications [Figure 8]; latent saphenous neuritis, reported as cutaneous paresthesia along the medial ankle, extending to the foot and hallux persisted for 3 months post-operatively. Patient has had no recurrence of tumor growth, functional deficits, or lingering sensory defect to the ankle.

Angioleiomyoma accounts for less than 4.5% of all soft tissue tumors.¹ Clinically benign, angioleiomyomas histologically arise from vascular, smooth muscle.² Most often reported in the lower extremities (50-70%), it occurs most frequently in females (2:1 ratio) between the 3^rd-5^th decades of life.^2,3 Unlike this case, the tumor often (58%) presents with pain, growing to a diameter less than 2cm in the majority of cases.³ Pain is related to local tissue hypoxia and compression of local neurovascular structures. When present, pain is characteristically paroxysmal and sensitive to temperature changes.³ Suspected etiologies of tumor growth include trauma, stasis changes as well as hormonal changes, particularly estrogen.² Plain films are the mainstay of most tumor evaluations. Angioleiomyoma has distinguishing features on ultrasound and MRI. Ultrasound imaging reveals a low echoic, hyper-vascular, heterogenous well-circumscribed lesion, while MRI shows slight hyperintense signaling on T1 and a heterogenous hyperintense signal on T2.²

Due to its medical paucity, it is rarely diagnosed pre-operatively; a reasonable differential diagnosis should include liposarcoma, myopericytoma, glomus tumor and leiomyoma. Surgical excision is diagnostic and curative in most clinical scenarios. Angioleiomyomas carry a low recurrence rate and only 7%³ have been known to undergo malignant transformation. A clinical zebra, angioleiomyoma has a predilection for the lower extremity and thus, its classic presentation should be a clinical consideration when assessing solidary nodular masses.

References:

1. Bodapati, V.S. and Sunderamoorthy, D. Angioleiomyoma—rare soft tissue tumor of the foot and ankle, review of two patients and review of the literature. Journal of Surgical Case Reports. 2021; 12:1-3.

2. Aljarbou, O. and Sngueza, O.P. Angioleimyoma. Pathology Outlines [online]. Available at: https://www.pathologyoutlines/com/topicssoftitssueangioleiomyoma.html/ [Accessed 1 August 2022].

3. Woo, K. et al. Clinical Experience with Treatment of Angioleiomyoma. Arch Plast Surg. 2014; 41:374-378.

4. Freedman, A. M. (1989, February).Angioleiomyomas of the extremities: report of a case and review of the Mayo Clinic experience. Europe PMC. Retrieved January 27, 2022, from https://europepmc.org/article/med/2911634

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