Targetoid Hemosiderotic Hemangioma Workup

Updated: Mar 05, 2018
  • Author: J Andrew Carlson, MD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies

Laboratory testing is not necessary in targetoid hemosiderotic hemangioma (THH) once a firm histopathologic diagnosis has been made. Occasionally, testing for human herpesvirus 8 and the human immunodeficiency virus is relevant, if the clinical and pathologic evaluation of the lesion has raised the issue of Kaposi sarcoma (KS) in the differential diagnosis. [10]


Imaging Studies

In many cases, dermoscopy can determine if a vascular lesion is present. Dermatoscopic evaluation can identify characteristic red or blue-black lagoons of superficial vascular ectasias, as similarly identified in angiokeratoma and hemangioma. Background shows brownish coloration secondary to hemosiderin deposition, not the pigment network or pigment globules expected in a melanocytic proliferation. The most common dermoscopic pattern in targetoid hemosiderotic hemangioma (71.4% of all cases) is the presence of central red and dark lacunae and a peripheral circular reddish-violaceous homogeneous area. [23]



If the clinical diagnosis is questionable or if clinical or patient concern exists regarding possible malignancy, a skin biopsy is warranted for definitive diagnosis. If punch biopsy is used, sampling of the central papular area produces the most diagnostic information. If the lesion is large, an excisional biopsy is helpful in avoiding possible sampling error.

Immunohistochemically, the dilated and slitlike vascular vessels will be labeled by lymphatic endothelial markers D2-40 and VEGFR-3 and will be negative or only focally positive for vascular endothelial markers such as CD34 and CD31, as well as for alpha-smooth muscle actin, which marks surrounding pericytes. [24] In situ hybridization for human herpesvirus 8 (HHV-8), which is found in more than 90% of lesions of KS, is not identified in the endothelial cell nuclei of targetoid hemosiderotic hemangioma. [25]


Histologic Findings

Targetoid hemosiderotic hemangioma shows a biphasic vascular pattern with a wedge-shaped profile, in which the base abuts the epidermis. Depending on targetoid hemosiderotic hemangioma age and size, well-formed dilated vascular spaces with protuberant endothelium are present in the superficial dermis, and compressed (pseudoangiosarcomatous) vascular spaces are present within the deeper reticular dermis. In most cases, protruding or hobnailed endothelial cells line superficial vessels. Not uncommonly, a feeder vessel is located at the apex. The feeder vessel is a muscular vessel found in association with dilated lymphatic vascular spaces. Variable amounts of hemosiderin and extravasated red blood cells may be present between the dermal vascular channels. Note the images below.

Targetoid hemosiderotic hemangiomas are biphasic v Targetoid hemosiderotic hemangiomas are biphasic vascular tumors that show superficial telangiectases, often lined by hobnailed endothelial cells and deeper slitlike vascular spaces. Note the solitary angiokeratomalike change: the irregular epidermal hyperplasia overlying numerous, blood-filled, dilated vascular spaces in which the lumens diminish with descent into the subjacent dermis (hematoxylin and eosin, original magnification X40).
Siderophages and extravasated red blood cells are Siderophages and extravasated red blood cells are located at the periphery and between the deep dissecting vascular spaces of targetoid hemosiderotic hemangioma. Prussian blue stain for iron outlines the margins and highlights abundant hemosiderin deposition (Prussian blue, original magnification X100).

A lack of cytologic atypism and multilayering of endothelial cells militates against a diagnosis of angiosarcoma or its variants. An absence of plasma cells, the presence of hobnailed endothelial cells, and superficial vascular ectasia point to a diagnosis of targetoid hemosiderotic hemangioma rather than KS. Correlation with clinical history also aids in discriminating targetoid hemosiderotic hemangioma from angiosarcoma variants or KS. A history of radiation, chronic lymphedema, or presentation of an ill-defined bruise on the head and neck of an older individual is typical of angiosarcoma. KS presents either as widespread multiple lesions in immunocompromised patients or as multiple lesions of the lower extremities in older patients of Jewish or Mediterranean ethnicity. In addition, the endothelial cells of KS harbor HHV-8 DNA, whereas those of targetoid hemosiderotic hemangioma do not. [26] Note the image below.

Histologically, targetoid hemosiderotic hemangioma Histologically, targetoid hemosiderotic hemangioma (hobnail hemangioma) can mimic both malignant processes (low-grade angiosarcoma variants) and cutaneous manifestations of systemic disease (Kaposi sarcoma in AIDS). In this instance, the promontory sign of Kaposi sarcoma is replicated by targetoid hemosiderotic hemangioma. Lymphangiectases envelop an arteriole and are surrounded by dilated blood-filled telangiectases (hematoxylin and eosin, original magnification X200).