Targetoid hemosiderotic hemangioma: A review article

Area of Science:

• Dermatology
• Pathology
• Vascular Lesions

Background:

• Targetoid hemosiderotic hemangioma (THH), also known as hobnail lymphatic malformation (HLL), is an uncommon acquired vascular lesion.
• Its etiology is unclear, but it may arise from trauma causing micro-shunts between capillaries and lymphatic vessels.
• THH affects adults aged 9–78 with no gender predilection.

Purpose of the Study:

• To review the clinical, histological, and immunohistochemical features of THH.
• To explore differential diagnoses for THH.
• To enhance awareness of THH for accurate diagnosis.

Main Methods:

• Review of clinical, histological, and immunohistochemical characteristics of THH.
• Comparison with differential diagnoses including Kaposi's sarcoma, solitary angiokeratoma, retiform hemangioendothelioma, and Dabska tumor.

Main Results:

• Clinically, THH presents as asymptomatic, well-circumscribed lesions with a central papule and peripheral ecchymotic ring, resembling a "bull's-eye".
• Histologically, it shows dilated vascular channels with hobnail endothelial cells, extravasated red blood cells, hemosiderin, and D2-40 positivity.
• Differential diagnoses include Kaposi's sarcoma, solitary angiokeratoma, retiform hemangioendothelioma, and Dabska tumor.

Conclusions:

• Increased awareness of the targetoid appearance of THH is important for diagnosis.
• Clinical-pathologic correlation is essential to differentiate THH from more concerning vascular lesions.
• Misdiagnosis can occur if branching telangiectatic vessels and purpura are not correctly identified as THH.