Vascular structures
Blood vessels are critical to the survival and growth of cells and tissues. The rate of growth and ultimate tumor size, whether benign or malignant, is governed at least in part by the tumor’s ability to derive ample blood flow to support the metabolic demands of its cells. Therefore, tumors may manifest signs of an increase in blood vessels and flow. This is readily observed in many basal cell carcinomas (BCCs) in which the clinical morphology often reveals telangiectasias. Although other tumors may not clinically manifest vasculature, vessels are indeed present but may be of small caliber or situated deeper within the skin. Dermoscopy, by providing magnification and visual access to subepidermal structures, has permitted clinicians to observe many of these vessels
It has the following subchapters:
- Anatomy of normal skin vasculature
- Vessels in the tumor micro environment
- Arborizing blood vessels
- Hairpin vessels
- Milky red globules / areas
- Glomerular vessels
- Comma vessels
- Dotted vessels
- Linear irregular vessels
- Polymorphous vessels
- Corkscrew / tortous vessels
- Crown vessels
- Strawberry pattern
- String of pearls pattern
Currently two different terminologies are used: the descriptive terminology and the metaphoric terminology. dermoscopedia uses both approaches because most individuals are more familiar with the metaphoric terms than with the descriptive terms.
A table with the descriptive vessel terminology can be found here,
The skin receives vascular sup- ply through superficial and deep vascular plexuses in the dermis (Fig. 12.1). These plexuses constitute anatomic landmarks in skin histology—the superficial vascular plexus marks the junction between the papillary and reticular dermis, whereas the deep vascular plexus separates the reticular dermis from subcutaneous fat (Lever). The superficial plexus is made up of anastomosing small-caliber arterioles that branch into capillaries, which extend into dermal papillae to sup- ply the overlying epidermis, as well as envelop adnexal structures. The deep plexus is made up of medium-caliber vessels, which emanate from larger vessels that traverse the adipose septae of the subcutis. Addition- ally, the deep plexus connects with the superficial vascular plexus through vertically oriented vessels.
Another more recently described vascular feature is the pattern of follicular red dots, which have been described in active discoid lupus erythematosus. The follicular red dots are seen surrounding the hair follicle openings and consist of regularly distributed, concentric reddish dots in a region of alopecia. This may represent dilation of blood vessels with extravasation of red blood cells surrounding the widened infundibula.
The recognition of vascular structures under dermoscopy has become increasingly important for a range of diagnoses. The identification of specific vascular characteristics is an important element of the two-step dermoscopic algorithm. When the lesion is categorized as a nonmelanocytic lesion, vascular features can help to diagnose the lesion more specifically, and hence guide management (Level 5 of the revised two-step dermoscopic algorithm). If the lesion is clearly recognized as a melanocytic tumor, then the identification of vessel type and distribution may facilitate the differentiation between benign and malignant diagnoses (Level 6 of the revised two-step dermoscopic algorithm). For more ambiguous cases in which the lesion cannot be easily classified as melanocytic or nonmelanocytic, the clinician may need to rely on vascular structures as the only recognizable features that can assist in the diagnosis.
In conclusion, it has become apparent that a finite number of morphologically distinct blood vessels can be visualized under dermoscopy. The vessel morphology and distribution along with other accompanying features can assist the clinician in correctly identifying many benign and malignant lesions. In general, vessels in melanocytic lesions include dotted vessels, comma vessels, linear irregular vessels/serpentine vessels, milky red globules, vascular blush, and polymorphous vessels. Vessels suggestive of nonmelanocytic lesions include arborizing vessels, hairpin vessels, glomerular vessels, crown vessels, and dotted vessels in a string of pearls pattern.
