Angiomatosis with angiokeratoma-like features in children: a light microscopic and immunophenotypic examination of four cases.

We have identified three patients with an initial clinical or biopsy diagnosis of angiokeratoma, all of whom were found to have a more extensive vascular lesion within the surgical excision. A fourth patient with identical histologic findings had no specified clinical diagnosis and his first procedure was excisional. The patients ranged in age from 7 to 16 years, and the lesions were located on the buttock, thigh, calf, and foot. Macroscopic appearances included mildly keratotic pink-red or blue-grey macules (three cases) and pink macules with focal ulceration (one case). In three of the four cases, a shave biopsy diagnosis of angiokeratoma had been made, and the extensive and deeply infiltrative nature of the vascular proliferation was recognized only at subsequent resection, at which point angiomatosis was diagnosed. In the fourth case. excisional biopsy was attempted at presentation, and the superficial morphology was angiokeratoma-like, but the vascular proliferation was present in the deep subcutaneous fat. CD31 and CD34 reactivity was present in the superficial and deep vessels in all cases, and lesional vessels were rimmed by a bland population of smooth muscle actin positive pericytes, findings that differentiate these cases from angiokeratoma, which has previously been reported to be CD34 negative. We conclude that the dilated vascular spaces that typify angiokeratoma may also be seen overlying a deep vasoformative process that is not amenable to resection, and suggest that caution should be exercised in evaluating small biopsies with angiokeratoma-like appearance.