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A 3-month-old, otherwise healthy boy was referred to the pediatric dermatology clinic for a “hemangioma” involving the left second toe, present since birth. The child's mother stated that the lesion had enlarged significantly since birth, although it seemed to be painless. No complications had occurred, and there was no family history of vascular birthmarks.

Physical examination showed a spongy, flesh-colored swelling of the toe with a slight bluish hue and an approximately 1-cm erythematous nodule at the distal dorsal surface, just proximal to the nail (Fig. 1). The toe measured 4.5 cm in diameter and was notably warm but nontender. There were no significant findings on skin examination elsewhere. A Doppler ultrasound was performed (Fig. 2).

What is the diagnosis?

  1. Top of page
  2. What is the diagnosis?
  3. Imaging Results
  4. Discussion
  5. References

Diagnosis: Arteriovenous malformation

Imaging Results

  1. Top of page
  2. What is the diagnosis?
  3. Imaging Results
  4. Discussion
  5. References

Doppler ultrasound showed a large tangle of tortuous vessels in the subcutaneous tissues of the second toe with low-resistance arterial waveforms, consistent with an arteriovenous malformation (AVM) (Fig. 2). Pulsation and a thrill on palpation were further clinical signs supportive of the diagnosis. Magnetic resonance imaging demonstrated multiple flow voids in the left second toe mass. Three-dimensional magnetic resonance angiography (MRA) demonstrated that an enlarged anterior tibialis artery supplied the AVM through an enlarged dorsalis pedis artery, with early venous drainage through multiple small venules into the lesser saphenous vein. There was no osseous involvement.

Discussion

  1. Top of page
  2. What is the diagnosis?
  3. Imaging Results
  4. Discussion
  5. References

AVMs are fast-flow malformations defined by a direct connection between arteries and veins without intervening capillaries. Congenital, cutaneous presentations of AVM are exceedingly rare. Furthermore, to our knowledge there has been only one prior report of an AVM on the toe, but that lesion was not evident at birth [1].

The natural history of AVM is typically slow progression over time, with acute changes classically noted after trauma or with puberty [2]. Clinical severity can be classified into one of four stages. Stage 1 comprises a frequently subtle, pink patch that may be mistaken for a capillary malformation (CM) or may be distinguished by warmth, pulsatility, or a thrill on palpation. Stage II shows further progression, with skin discoloration and involvement of underlying tissues. Stage III demonstrates deeper tissue destruction. Stage IV is characterized by advanced severity leading to cardiac compromise [3].

The diagnosis of AVM is often suspected clinically and then confirmed, as in our patient, using Doppler ultrasound and MRA imaging, with or without conventional angiography. At the time of initial presentation, the differential diagnosis in our case included the full spectrum of vascular birthmarks, although the unusual appearance and location made the majority of these unlikely. The fully present nature at birth essentially eliminated the referring diagnosis of infantile hemangioma. The clinical appearance was also unusual for congenital hemangiomas (e.g., rapidly involuting congenital hemangioma and noninvoluting congenital hemangioma) or the two vascular tumors potentially associated with Kasabach-Merritt syndrome: tufted angioma or kaposiform hemangioendothelioma. Infantile fibrosarcoma was a consideration, but the growth lacked the translucent appearance and firm, infiltrative consistency often typical of this malignancy. Lastly, our patient had no family history or additional clinical features indicative of an AVM-associated syndrome such as capillary malformation AVM, Osler-Weber-Rendu, or familial Parkes-Weber.

Treatment of asymptomatic, early stage AVMs is generally conservative because of low cure rates and the high risk of treatment-induced exacerbation. Options for symptomatic AVM include surgery, embolization, or both. Amputation is reserved for severe complications such as tissue necrosis, deformity, and loss of function [4]. Regardless of the treatment, the majority of patients require long-term clinical and imaging follow-up.

Because of the location and early, rapid enlargement of our patient's AVM, he underwent glue embolization at 6 months of age. Unfortunately, despite initial clinical improvement, his course was subsequently complicated by recurrent pain, swelling, and infection. The child thus underwent amputation at the metatarsophalangeal joint at 8 months of age. He continues to be followed closely, with no evidence of recurrence at 18 months of age.

References

  1. Top of page
  2. What is the diagnosis?
  3. Imaging Results
  4. Discussion
  5. References