Reflected light microscopy, vascular patterns in skin tumors

Author: Prof. Dr. med. Peter Altmeyer

Last updated on: 29.10.2020

Definition
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Observation of raised or sunken skin tumours by means of reflected light microscopy and listing of characteristic features; adjacent vessels serve as a reference. 38% of the tumours are visibly vascularised, most frequently basal cell carcinomas with 98%. The sharper a vessel is, the more superficial its anatomical position is.5 Vascular patterns can be defined that differ significantly from normal skin (see Table 1).

General information
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Further features extend the diagnostic significance (see also Table 2):In epithelial tumors, in which maturation of the keratinocytes takes place in horny cells, punctiform or hairpin vessels appear, surrounded by white keratinocyte courtyard, which changes into a yellowish mass in the center of the tumor, which corresponds to keratinEarly forms of almost all tumors often have delicate capillaries (diameter 10-20 μm), viewed with 40x magnification. This facilitates the diagnosis of basal cell carcinoma even before a rim appears or the recognition of recurrences with tree vessels in the scar area is possible. Do not apply pressure because of the danger of vascular compression.

Literature
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Kreusch J Koch F (1996) Reflected light microscopic characterization of vascular patterns in skin tumors. dermatologist 47: 264-272
Ruocco E et al (2004) Noninvasive imaging of skin tumors. Dermatol Surg. 30(2 Pt 2): 301-310
Wolf IH et al (1997) Epiluminescence microscopy for the diagnosis of pigmented skin tumors. Dermatologist 48: 353-362
Zalaudek I et al (2004) Clinically equivocal melanocytic skin lesions with features of regression: a dermoscopic-pathological study. Br J Dermatol 150: 64-71

Tables
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Vessel pattern in reflected light microscopy

Description	Features
Tree containers	Heavily branched, tortuous vessels that are superimposed on the tumour. Acute-angled (50-90%) branching of the thick main vessels to the finest capillaries. Occasional crossing of branches. Calibre diameter 0.18 mm of the larger to 0.055 mm of the secondary vessels. The larger ones correspond macroscopically to telangiectasia.
Coronary vessels	The superimposed vessels surround the tumor and are less curved and branched. Average diameter 0.14-0.03 mm. Exclusive occurrence in sebaceous hyperplasia, where they encompass the sebaceous glands and the excretory duct.
Comma vessels	Short, strongly curved vessels of about 0.06 mm calibre, which are supported by the tumour. Short course parallel to the skin surface, then disappearing again in depth. Occasional and irregular occurrence, rarely branching. Vessels typical for dermal nevi.
Hairpin-like vascular loops, starting from the dermal plexus, apparently supply numerous tumors. Depending on the length of the loop, different vascular patterns develop:
Dot Vessels	Thin tumours have only short capillary loops, which impress as red spots. These dots are not surrounded by a pigment network. This results in a reddish shade in tumours with a low pigment content. Thickness about 0.03 mm. Occurs in malignant melanomas and numerous epithelial tumours.
Hairpin vessels	Long vascular loops of thicker tumors. Varying degrees of tortuosity and tangling, calibre 0.03 mm. Easily recognizable by tumor edges, on which they usually lie at an angle. In the tumour centre of nodular tumours, they appear as point vessels due to their vertical growth. Frequently occurs in thicker malignant melanomas, seborrhoeic keratoses and other keratinising tumours. Hairpin-like vessels can also be found in scars, starting from the edges of the incision and running parallel to the skin surface.

Skin tumours and their characteristic reflected-light microscopic features

Disease	Reflected light microscopic features
Basalioma	Tree-like vascular structure already in early forms, vessels sharply defined due to superficial position.
Dermal melanocytic nevi	Large-caliber commixtures.
Epidermocorneal melanocytic nevi	Mirror form with central, small areas with dot or hairpin vessels.
Malignant melanoma	Eccentric, flat trimming with evenly arranged point and hairpin vessels. With increasing thickness, the hairpin vessels increase in size compared to the point vessels. From 2 mm tumour thickness on also superimposed, branched vessels. Regression zones show no characteristic structures. Amelanotic melanomas show no keratinization, possible pigment residues and eccentrically accentuated point and hair vessel arrangement.
Pointed nevus	Shooting target type construction with a low-pigment centre, in which there are numerous, evenly arranged point vessels and a more pigmented rim.
Keratinising tumours	White courtyard around hair or spot vessel with following yellowish keratin zone.
Hyperplasia of the sebaceous glands	Coronary vessels surrounding the excretory duct.