Conditions that cause excess vascular spaces (increased, dilated, or proliferating vessels) in the dermis typically fall into benign reactive changes, vascular malformations, benign neoplasms, and malignant tumors. [1, 2, 3]
1. Benign Vascular Proliferations (Neoplasms)
- Cherry Angiomas: Very common, benign acquired lesions that feature closely aggregated, dilated, congested capillaries in the papillary dermis. [1, 2, 3, 4]
- Pyogenic Granulomas: Rapidly growing, friable papules. Histology shows a lobular arrangement of newly formed capillaries with plump endothelial cells and a mix of inflammatory cells. [1, 2, 3, 4, 5]
- Tufted Angiomas & Hemangiomas: Characterized by "cannonball" clusters of small, capillary-like vascular spaces scattered throughout the dermis. [1, 2, 3, 4]
2. Vascular Malformations
- Capillary Malformations (e.g., Port-Wine Stains): Present at birth. Histology reveals ectatic (permanently dilated) thin-walled small vessels in the superficial and mid-dermis without significant endothelial proliferation. [1, 2, 3]
- Venous & Lymphangiomas: Venous malformations show large, irregular, thick-walled vascular spaces. Lymphangiomas are marked by dilated lymphatic channels in the papillary dermis, often pushing directly up against the epidermis. [1, 2, 3, 4]
3. Reactive & Acquired Vascular Changes
- Venous Stasis Changes / Pseudo-Kaposi Sarcoma: Frequently seen on the lower legs of older adults due to venous insufficiency. Histology shows prominent, tangled clusters of thick-walled capillaries with background fibrosis, extravasated red blood cells, and hemosiderin deposition. [1, 2, 3]
- Reactive Angioendotheliomatosis: A rare, benign proliferation of plump endothelial cells within dilated dermal vessels, usually triggered by an underlying systemic infection, autoimmune disease, or intravascular clot. [1, 2]
4. Malignant & Borderline Vascular Tumors
- Kaposi Sarcoma: Often presents as violaceous plaques. Key histologic features include a proliferation of spindle cells dissecting through collagen bundles, accompanied by slit-like or irregular, jagged vascular spaces containing red blood cells. [1, 2, 3, 4]
- Angiosarcoma: An aggressive malignancy usually found on sun-damaged skin (e.g., head and neck of older adults). Histology is defined by infiltrating, irregular, anastomosing vascular channels lined by atypical, hyperchromatic endothelial cells that frequently pile up or layer upon each other
