Melanocytic Neoplasms: Dermoscopic Structures and Histopathologic Correlation
| Dermoscopic structures | Schematic illustration | Definition | Histopathologic correlation |
|---|---|---|---|
| Pigment network | Grid-like network consisting of pigmented lines and hypopigmented holes | Melanin in keratinocytes or melanocytes along the dermoepidermal junction | |
| Network lines correspond to the rete ridges | |||
| Holes correspond to the suprapapillary plate | |||
| Pseudonetwork | Diffuse pigmentation interrupted by adnexal opening | Pigment in the epidermis or dermis in which the rete ridges are attenuated | |
| Usually seen in facial lesions | |||
| Negative pigment network | Serpiginous interconnecting hypopigmented lines that surround irregularly shaped pigmented structures resembling elongated curvilinear globules | Remains unknown | |
| Presumed to be related to bridging of rete ridges or large melanocytic nests in the papillary dermis, resulting in compression of adjacent rete ridges; these nests may correspond to globules that are not spherical in shape | |||
| Aggregated globules | More than three clustered, well- demarcated, round to oval, symmetric structures, or three or more of these structures aligned at the lesion's perimeter | Nests of melanocytes at the dermoepidermal junction | |
| May be brown, black, or blue | |||
| Diameters are greater than 0.1 mm | |||
| Dots | Small, round structures of less than 0.1 mm in diameter | Aggregates of melanocytes or melanin granules | |
| May be black, brown, or blue-gray | |||
| Streaks (pseudopods and radial streaming) | Streaks are radial projections at the periphery of the lesion, extending from the tumor toward the surrounding normal skin; may be brown or black | Confluent junctional nests of melanocytes | |
| Pseudopods are streaks with finger-like projections with small knobs at the tips | |||
| Radial streaming is streaks without knobs at the tips | |||
| Peppering (or granularity) | Tiny, blue-gray granules | Melanin deposited as intracellular (mostly within melanophages) or extracellular particles in the upper dermis | |
| Structureless areas | Devoid of dermoscopic structures within the lesion and without manife sting any regression structures | Relative decreased concentration of melanin or flattening of rete ridges | |
| Tend to be tan to light brown, but have lighter pigment compared with the rest of the lesion | |||
| Peripheral light brown or tan structureless areas | Structureless areas (as above), located at the periphery of the lesion | Partial or complete flattening of the rete ridges | |
| Increased number of pigmented atypical melanocytes predominantly at the dermoepidermal junction | |||
| Diffuse scattering of melanocytes in the spinous layer of the epidermis | |||
| Blotches | Dark brown to black homogeneous areas of pigment that obscure visualization of any other structures | Aggregates of melanin in the stratum corneum or throughout all layers of the skin | |
| Regression structures | Include scar-like depigmentation (lighter than the surrounding uninvolved normal skin; appear shiny white under polarized dermoscopy) often combined with peppering; combination of scar-like depigmentation and peppering gives the appearance of a blue-white veil | Scar-like changes/white areas: thickened fibrotic papillary dermis | |
| Blue areas: correlate with melanosis type of regression | |||
| Blue-white veil | Confluent blue pigmentation with an overlying white ground-glass haze | Aggregation of heavily pigmented melanocytes or melanophages in combination with compact orthokeratosis of the stratum corneum | |
| White shiny structures (more conspicuous with polarized dermoscopy) | Rosettes: appear as four white shiny points creating a pattern reminiscent of a four- leaf clover A4 | Histopathologic correlation has not been fully explained | |
| Crystalline structures: short, white, shiny linear streaks that are often parallel or orthogonal to each other A5, A6 | Altered collagen or fibrosis in the dermis | ||
| White shiny areas: appear as larger structureless areas of shiny white color | Altered stromal matrix | ||
| Parallel pigment pattern | On volar skin (i.e., palms and soles) | Pigmented melanocytes in the furrows (crista limitants) or ridges (crista intermedia) on skin of palms and soles | |
| Parallel rows of pigmentation following the furrows (as seen in nevi) or ridges (as seen in melanoma) of the dermatoglyphics |
Nonmelanocytic Neoplasms: Dermoscopic Structures and Histopathologic Correlation
| Dermoscopic structures | Schematic illustration | Definition | Histopathologic correlation |
|---|---|---|---|
| Milia-like cysts | Round whitish or yellowish structures that shine brightly (like “stars in the sky”) under nonpolarized dermoscopy | Intraepidermal keratin-filled cysts | |
| Further subclassified as small and starry, and as large and cloudy A9 | |||
| Comedo-like openings | Blackhead-like plugs on the surface of the lesion | Concave invaginations in the surface of the epidermis filled with keratin; some of these invaginations may correspond to follicular openings filled with keratin | |
| Fingerprint-like structures | Delicate, thin, light brown parallel running lines that do not interconnect to form a grid | Epidermal ridges | |
| Gyri and sulci | Gyri (ridges or fat fingers) and sulci (fissures) that create a cerebriform surface | Epidermal ridges with or without keratin filling the invaginations | |
| These invaginations can be filled with keratin, creating crypts | |||
| Moth-eaten borders | Concave invaginations of the lesion border | — | |
| Pigment network–like structure | Grid-like pattern that can resemble the pigment network seen in a melanocytic neoplasm | Ridges, crypts, and comedo-like openings distributed in a manner that gives the appearance of a grid | |
| Correspond to interconnecting epidermal ridges on the skin; the holes correspond to comedones or crypts | |||
| Lines tend to appear broader compared with the pigment network seen in nevi | |||
| Leaf-like structures | Brown to gray-blue discrete bulbous structures that may coalesce to create a shape that resembles a leaf | Large pigmented basal cell carcinoma tumor nests in the upper dermis | |
| Spoke wheel–like/concentric structures | Well-circumscribed brown to gray-blue-brown radial projections meeting at a darker brown central hub | Basal cell carcinoma tumor nests radiating from the dermoepidermal junction | |
| Large blue-gray ovoid nests | Large, well-circumscribed ovoid areas; larger than globules | Large basal cell carcinoma tumor nests in the dermis | |
| Blue-gray globules or dots | Multiple, nonaggregated, round, well-circumscribed structures | Small basal cell carcinoma tumor nests in the dermis | |
| Lacunae | Red (hemangioma), maroon (hemangioma and angiokeratoma), or black (angiokeratoma) lagoons often separated by septae | Dilated vascular spaces |
Vascular Structures Most Commonly Seen in and Associated with Nonmelanocytic Tumors
| Dermoscopic structures | Schematic illustration | Definition (morphology) | Diagnostic associations |
|---|---|---|---|
| Glomerular vessels | Coiled vessels mimicking the glomerular apparatus of the kidney | Bowenoid actinic keratosis, Bowen disease/squamous cell carcinomaA11,A13 | |
| Clear cell acanthoma | |||
| Hairpin vessels | U-shaped vessels | Keratinizing tumors such as keratoacanthoma and seborrheic keratosisA7,A11,A14 | |
| Not infrequently, may be twisted on its axis | |||
| Background: white halo common in keratinocytic tumors | |||
| U-shaped vessels | Irritated seborrheic keratosis, melanoma, basal cell carcinomaA15 | ||
| Not infrequently, may be twisted on its axis | |||
| Background: pink halo or pink background common in irritated seborrheic keratosis, but can also be seen in cutaneous malignancies | |||
| Arborizing vessels | Vessels with large diameter, branching irregularly into fine capillaries | Basal cell carcinomaA11, A13 | |
| Can also be seen in cysts, furuncles, and other adnexal tumors | |||
| Crown vessels | Branching or nonbranching vessels radiating toward the center of the lesion but without crossing its center | Sebaceous hyperplasiaA11 | |
| Molluscum contagiosum | |||
| Often associated with white/yellowish popcorn-like globular structures | |||
| Dotted or glomerular vessels in “string of pearls” or serpiginous distribution | Vessels distributed in a serpiginous pattern | Clear cell acanthoma | |
| Strawberry pattern | White-yellow follicular openings surrounded by a white halo, over a red background | Actinic keratosisA16 |
note: The presence of a given vessel morphology is not exclusive to a particular diagnosis. For example, arborizing vessels are commo nly seen in basal cell carcinoma, but they can also, on rare occasions, be seen in melanoma and intradermal nevi. Another example, hairpin vessels, are commonly associated with seborrheic keratoses, but they can also be seen in melanoma. With that said, this appendix highlights vessels t hat are most commonly associated with nonmelanocytic tumors.
Vascular Structures Most Commonly Seen in and Associated with Melanocytic Tumors
| Dermoscopic structures | Schematic illustration | Definition (morphology) | Diagnostic associations |
|---|---|---|---|
| Comma-shaped vessels | Slightly curved vessels | Dermal nevi, congenital melanocytic neviA11 | |
| Dotted vessels | Red dots (0.01 to 0.02 mm) | Spitz nevi, early melanoma (dotted over milky-red background)A11 | |
| Clark nevi (dotted over tan background) | |||
| Serpentine vessels | Irregular linear/undulating short vessels | Melanoma, congenital neviA11 | |
| Milky-red globules/vascular blush | Ill-defined globules of milky-red color and ill-defined areas of milky-red color | Amelanotic melanomaA11 | |
| Polymorphous vessels | Combination of two or more vessel morphologies | MelanomaA14 | |
| Most common combination is dotted and serpentine vessels | |||
| Corkscrew vessels | Coiled and tortuous vessels | Cutaneous melanoma metastases, nodular melanoma, desmoplastic melanoma |
note: The presence of a given vessel morphology is not exclusive to a particular diagnosis. For example, dotted vessels can be seen i n melanocytic tumors, but they can also be seen in squamous cell carcinoma,A12 basal cell carcinoma,A15 porokeratosis,A17 and clear cell acanthoma.A12 Another example, polymorphous vessels, are commonly associated with me lanoma, but they can also be seen in basal cell carcinoma,A15 and stasis dermatitis. With that said, this appendix highlights vessels that are most commonly associated with melanocytic tumors.
Information from references A10 through A12, and A14, A15, and A17.
Schematic illustrations copyright © Ashfaq A. Marghoob, MD, and Natalia Jaimes, MD.
