Dusky erythematous plaques over the lower leg associated with bony deformity.

A 19-year-old man presented with multiple painless bluish-red skin lesions on the dorsum of the right foot since early childhood. Gradually, these lesions increased in number and progressed proximally. He had several episodes of profuse bleeding after local trauma requiring compression bandaging. At the age of 17, he spontaneously developed mild, persistent pain in the right foot with difficulty in walking. There were no systemic complaints.

On examination, there were multiple dusky erythematous to violaceous firm nodules and nodulo-plaques of variable sizes over the right leg and dorsum of the foot [Figure 1a, b]. These lesions coalesced into large confluent plaques distally and were discrete and smaller proximally. There were no dilated veins. Thrill and bruit were noted over the right leg and foot. The affected limb was warmer and 4 cm wider at the calf and 2.5 cm longer than the other.

Figure 1

(a) multiple dusky erythematous to violaceous firm nodules and plaques of variable sizes over dorsum of right foot and lower leg; (b) close-up view of firm, non-compressible, dusky erythematous plaque on right leg; (c) dermoscopy (dermlite 4/ no interface liquid/polarizing mode/ 10x magnification) revealed multicolored areas of blood-filled lacunae (dotted arrows) with multicolored areas of varying intensity showing rainbow appearance (solid arrows); (d) histopathology revealed clusters of small vessels in superficial and deep dermis associated with prominent hemosiderin deposition (hematoxylin and eosin, 100x); (e) hemosiderin deposition stained positively with Perl's stain (100x)

Dermoscopy from one of the plaques on the foot revealed multicolored areas of blood-filled lacunae with rainbow patterns of varying intensities and dimensions [Figure 1c]. Histopathology revealed clusters of small vessels lined with plump endothelial cells in superficial and deep dermis associated with prominent hemosiderin deposition throughout the dermis [Figure 1d]. The hemosiderin deposition stained positively with Perl's stain [Figure 1e].

Doppler ultrasound and magnetic resonance angiography revealed high flow arteriovenous malformation in the right leg. Magnetic resonance imaging revealed destructive lesion and osteoporosis of the right navicular bone with cortical erosion.

Differential diagnosis included Klippel–Trenaunay syndrome (KTS) and Parkes Weber syndrome (PWS). The differentials of cutaneous lesions included Stewart–Bluefarb syndrome (SBS), acroangiodermatitis of Mali, verrucous hemangioma, and angiokeratoma circumscriptum neviforme. After a clinicopathological correlation with the radiological findings, the final diagnosis of PWS with SBS was considered. The patient was counseled and referred for selective embolization of the underlying malformation.

SBS occurs in the setting of congenital arteriovenous malformation leading to distal ischemia due to arteriovenous steal syndrome in the arterial segment distal to the malformation, hence resulting in an increase in the vascular endothelial growth factor followed by proliferation of endothelial cells and fibroblasts.[1] PWS includes a triad of high-flow arteriovenous malformation with a capillary or venous malformation and associated limb hypertrophy.[2] The severity of the associated angiodermatitis secondary to arteriovenous malformation is graded as Stage I: asymptomatic macules and plaques; stage II: pulsatile expansile lesions; stage III: destructive stage with complications like skin ulceration and lytic changes in underlying bones; and stage IV: overt heart failure.[3] The present patient had stage III involvement.

Due to the clinical resemblance of its papulo-nodules to Kaposi sarcoma (KS), SBS is also known as acroangiodermatitis or pseudo-KS. The dermoscopic appearance of the rainbow pattern has been described in SBS similar to KS.[3] In KS, there is a proliferation of atypical spindle cells and CD-34 positivity is seen in the endothelial cells and perivascular spindle cells, while in SBS, there is a reactive proliferation of the pre-existing vessels without any atypical spindle cell proliferation.

Acroangiodermatitis of Mali is usually seen in the adults and elderly. It is associated with chronic venous hypertension-like stasis dermatitis and pregnancy.[4] While SBS is unilateral, acroangiodermatitis of Mali may be bilateral. Verrucous hemangioma was ruled out as it is a congenital localized vascular malformation with unremarkable endothelial cell lining associated with reactive epidermal changes.[5] Angiokeratoma circumscriptum neviforme presents as well-circumscribed erythematous to blue-black, hyperkeratotic papules, nodules, or plaques, in a linear or segmental distribution, mostly over the lower extremities. It can co-exist with vascular malformations.[6] In the present case, the capillary proliferation was not restricted to the upper dermis as in angiokeratoma circumscriptum neviforme, but involved the entire dermis along with prominent perivascular hemosiderin deposition.

The treatment of SBS is complex and requires obliteration of the underlying arteriovenous malformation by embolization, endovenous ablative techniques, sclerotherapy, or surgery. Conservative measures include protection from local trauma, rest, compression stockings, and regular cardiac monitoring.[12]

The present case depicts the varied morphological manifestations and complications of skin and bone in lower limb arteriovenous malformation in a single patient, along with a detailed radiological and pathological evaluation. The unique reactive pseudo-KS-like cutaneous lesions in SBS with the characteristic dermoscopic and histopathological appearance is highlighted in the case.

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