HISTOPATHOLOGIC CORRELATIONS OF DERMOSCOPIC STRUCTURES Flashcards
which colors can melanin produce in dermoscopy ?
- brown, black, gray, blue
- depending on the amount of melanin & its depth within the skin
which colors do lipids, lymph, keratin produce in dermoscopy?
- yellow to orange
melanin color when it is located in
* stratum corneum/upper epidermis
* lower-mid epidermis
* dermis
- SC: black
- lower epidermis: brown
- dermis: blue / blue-gray
white color is due to…?
- depigmentation, fibrosis, alterations in the collagen matrix, or keratin within cysts
definition of pigment network
- intersecting brown lines creating a reticular grid-like or fishnet-like pattern with hypopigmented “holes”
- can be typical or atypical
histological correlation of pigment network
- lines correspond to melanin within the keratinocytes & the melanocytes along the rete ridges
- The “holes” of the network correspond to the suprapapillary plates
definition of typical or regular pigment network
* hallmark of ?
- lines that have minimal variation in their width and color
- hallmark of benign melanocytic nevi with a junctional component
name some non-melanocytic lesions in which typical pigment network can be seen
- ink- spot lentigo
- dermatofibroma
- supernumerary nipple
dermoscopic structures in melanocytic neoplasms
Dermoscopic Features with High Specificity for Melanocytic Neoplasms Present in Other Nonmelanocytic Lesions & Their Histopathologic Correlates
definition of atypical pigment network
- irregularly meshed with increased variability in thickness, color (mainly gray color) & distribution
- ass/w dysplastic nevi & SSM
histopathology of the atypical pigment network corresponds to…?
- disarrangement of the rete ridges
- a confluence of melanocytic nests
- changes in melanin distribution within the epithelium
body areas in which pigment network is usually absent ?
- face (pseudonetwork is present)
- palms & soles
definition of negative network
aka inverse network
- consists of elongated to curvilinear brown globular structures with relative hypopigmentation surrounding them
- When focusing on the hypopigmented area, it can take on the appearance of serpiginous lighter “lines” surrounding hyperpigmented globular structures
negative network is MCy ass/w…?
- melanomas arising in nevi
- Spitz nevi
- occasionally, small congenital nevi
histological correlation of negative network
- hypopigmented lines of the negative network correlate with broadened epidermal rete ridges, which often contain overlying surface dells and wedge-shaped hypergranulosis
- pigmented globules of the negative network correlate with a predominantly junctional proliferation of melanocytes along & between elongated rete ridges
structures that can resemble negative network
- shiny white lines
- reticular depigmentation
definition of angulated lines
- brown to brownish-gray dots that coalesce,
- forming lines that intersect at acute angles creating a zig-zag pattern
- and can further coalesce to create polygonal shapes such as rhomboids
- ass/w LM on H&N area or with lentiginous melanomas on chronically sun-damaged skin
definition of globules
- round to oval well-demarcated structures >0.1 mm in DM
- usually aggregated or at the periphery of a melanocytic lesion
histological correlation of globules
* brown
* blue
* white
- brown or black globules correspond to nests of melanocytes at the epidermis or DEJ
- Blue globules represent melanocytic nests in the dermis
- White globules correspond to melanocytes displaying balloon cell changes
globules located at the periphery of a pigmented lesions are indicative of..?
- horizontal growth in a nevus or SSM
features of globules in melanoma
- vary in size, shape & color
- are frequently found focally & randomly distributed at the periphery of the lesion
A focal cluster of globules located eccentrically at the periphery of a raised, otherwise homogeneous melanocytic lesion should raise suspicion for…?
- BAP1-inactivated melanocytic tumor (BIMT)
- aka “bapoma”
features of BAP1-inactivated melanocytic tumor (BIMT)
aka “bapoma”
- particular ** of melanocytic nevi with a biphasic cell population**
- consisting of a more banal-appearing dermal cell population corresponding with the globular component and a spitzoid population containing the loss of expression of BAP1 and corresponding with the homogeneous area of the lesion
- These lesions may also reveal shiny white areas when viewed with polarized light
Multiple BIMTs have been ass/w…?
- cancer syndrome with increased risk for uveal melanoma, cutaneous melanoma, mesothelioma, renal cell carcinoma, among others
definition of dots
- small, round, well-circumscribed structures smaller than globules ( < 0.1 mm in diameter, similar to the diameter of a terminal hair follicle)
- Their color varies from brown, black, gray, blue to red
histological correlation of dots
- brown, black, gray, blue dots correspond to melanin in different levels of the epidermis or dermis
- black dots correspond to melanin in the upper epidermis or stratum corneum
- brown dots to small melanocytic nests in the epidermis or the DEJ
- blue-gray dots to melanin in the upper dermis or in dermal melanophages (peppering, granularity, regression structures)
definition of streaks
- linear pigmented projections located at the periphery of SSMs or Reed’s nevi
- They project from the tumor and radiate out towards normal skin
- The term streaks encompasses radial streaming & pseudopods
streaks are ass/w…?
- radial growth phase of Reed’s nevi & SSMs
- Symmetrical distribution of streaks around the entire perimeter of a melanocytic lesion favors the Dx of a Reed’s nevus
- Streaks distributed asymmetrically or focally at the periphery favor the Dx of SSM
histologically streaks correspond to…?
- linearly confluent junctional nests of pigmented melanocytes at the periphery of the lesion
definition of homogeneous blue pattern
- presence of blue color with the absence of other dermoscopic structures throughout the entire lesion when viewed with nonpolarized light
- When viewed with polarized light, one can, on occasion, see shiny white lines
Histologically, a homogeneous blue pattern corresponds to…?
- densely pigmented melanocytes or melanophages in the dermis
DDx of homogeneous blue pattern
- blue nevi
- areas of extensive regression
- pigmented nodular melanoma
- epidermotropic metastatic melanoma
- nodular pigmented BCC
- radiation tattoos
definition of blotches
- heavily pigmented dark brown to black structureless areas occupying >10% of the lesion’s surface area that preclude the visualization of any other structure
- can be seen in melanocytic lesions, seborrheic keratoses (SK), angiokeratomaspigmented BCCs
- can be regular or irregular
regular vs irregular blotch
- regular: isolated symmetric, homogeneous, centrally located blotch, usually seen in melanocytic nevi with a reticular pattern at the periphery
- irregular: asymmetric, heterogeneous, off-centered pigmented areas. presence of multiple blotches is also considered atypical. most frequently ass/w melanoma or dysplastic nevi
histologically blotches correspond to…?
- abundant melanin in one or more layers of the epidermis +/- pigment in the underlying dermis
definition of black lamella
- specific type of blotch, that arises,
- due to the presence of excessive melanin in the stratum corneum
- usually a transient structure seen in some nevi after excessive UV exposure resulting in the accumulation of melanin in the stratum corneum, forming black dots and lamellar blotches
- Since black lamella & black dots are due to melanin in the stratum corneum, they can be removed by tape-stripping off the upper layers of the stratum corneum
- Blotches due to excessive melanin in areas below the stratum corneum cannot be tape-stripped away
regression structures encompass…?
- Granularity/peppering
- scarlike depigmentation
- areas displaying regression structures will be flat & nonpalpable
granularity or peppering
* consists of ..?
* histological correlation ?
- multiple tiny gray dots
- correlate with free melanin in the dermis or within melanophages
- can be seen in regression areas within a melanoma, in LPLK, occasionally in melanocytic nevi
Scar-like depigmentation
* consists of ?
* histological correlation ?
- white structureless areas that are lighter in color compared with surrounding perilesional skin
- This scarlike area often has a porcelain-white color
- In melanocytic lesions, the scarlike areas usually will not display shiny white lines or vessels
- Histopathologically, correspond to dermal fibrosis
shiny white structures are only seen in which type of dermoscopy ?
polarized
name the 3 morphologies of shiny white structures ( + examples )
- shiny white blotches & strands, seen primarily in BCC
- rosettes, seen primarily in AK/SCC
- shiny white lines, seen in melanoma, Spitz nevi, LPLK, dermatofibroma
Histologically, shiny white lines correspond to ?
- birefringent collagen bundles
- which are thought to be altered or new as a result of the tumor’s influence on the fibroblast and/or stroma
blue-whitish veil (BWV) consists of..?
* clinically corresponds to ?
- structureless blue area with an overlying white “ground-glass” haze
- Clinically, corresponds to the raised/palpable areas of a pigmented lesion
- MCy ass/w melanoma/ Reed nevi
histologically blue-whitish veil corresponds to ?
- heavily pigmented melanocytes in the dermis in combination with acanthosis & compact orthokeratosis
how does the pseudonetwork emerge ?
- Facial skin is characterized by a thin epidermis with a thin stratum corneum, relatively flat DEJ & multiple pilosebaceous units
- pseudonetwork pattern emerges when brown structureless/homogeneous pigmented areas are interrupted by hypopigmented holes corresponding to the adnexal openings
Histologically, pseudonetwork pattern corresponds to..?
- pigmented cells/melanin located in the epidermis with a flattened DEJ interrupted by adnexal/follicular openings
- what is the main DDx for acquired facial lentiginous lesions ?
- acquired lentiginous junctional nevi are rarely found on facial skin
- for lentiginous facial lesions, the main differential lies between a solar lentigo and LM
what is the earliest change in Lentigo maligna ?
annular-granular pattern
describe the features of annular-grannular pattern seen in LM
- earliest change in LM
- consisting of perifollicular changes characterized by
- tiny gray to brown dots around follicular openings
- asymmetric pigmentation around follicular openings (incomplete circles)
- gray circles
- concentric circles (circle within circle or isobar)
- target-like pattern (dot within a circle)
Dermoscopic Structures Present in Melanocytic Neoplasms Located in volar skin
Dermoscopic Structures Present in Melanocytic Neoplasms Located in mucosa
melanin inclusions in nails
name the 3 features of palmoplantar skin
- thick cornified layer
- presence of dermatoglyphics
- absence of hair follicles
name the 2 patterns of melanocytic neoplasms on palmoplantar skin
- parallel furrow
- parallel ridge
describe the parallel furrow pattern
- thin parallel pigmented lines in the furrows
- generally ass/w benign melanocytic lesions
- Histologically, corresponds to nevomelanocytes located in the rete ridges called crista limitans
- which corresponds to the dermatoglyphic furrows (sulcus superficialis)
how do nevomelanocytes located in crista limitans behave over nevomelanocytes located in crista profunda intermedia ?
- nevomelanocytes located in the crista limitans transfer pigment to overlying keratinocytes
- but nevomelanocytes located in rete ridges named crista profunda intermedia, which correspond to the crista superficialis (ridge), do not
- it is because of this , that presence of parallel furrow pattern is ass/w nevi on acral skin
where does melanoma in acral skin arise from ?
- melanoma believed to arise from stem cells residing around the eccrine ducts within the crista profunda intermedia
- results in the observation of pigment on the ridges, creating the parallel ridge pattern ass/w acral melanoma
- Histologically, parallel ridge pattern reveals melanocyte proliferation around the rete ridges ass/e acrosyringia (crista profunda intermedia)
variant of parallel furrow pattern ?
- lattice-like pattern
- characterized by parallel pigmented lines in the furrows accompanied by pigmented lines crossing the ridges connecting one parallel furrow to another
- Whereas the lattice-like pattern is commonly seen in nevi located on the arch of the foot, the furrow pattern is commonly seen between the arch and the weight-bearing surface of the foot
how is the fibrillar pattern created ?
- consists of pigmented lines that are oriented diagonally across both the furrows & the ridges
- All thin fibrillar lines are oriented in the same tangential direction
- arises due to repetitive mechanical pressure, resulting in the thickened stratum corneum growing out at a slant
- as the vertically oriented epidermal keratinocyte melanin pigment columns enter the stratum corneum, they start to angle towards the direction of the mechanical frictional forces. This is the histopathologic correlate of the fibrillar pattern
- fibrillar pattern can be seen in both nevi and melanomas located on the pressure-bearing surfaces of volar skin
what is the difference of mucosal skin over skin in other locations ?
- usually lacks a corneal layer
- In addition, the rete ridge pattern can be attenuated or consist of widened or thin rete ridges
which pattern is ass/w mucosal melanomas ?
- multicomponent pattern consisting of blue, gray, and white colors, regression structures, BWV & structureless areas
what is micro-hutchinson sign?
- presence of periungual skin pigmentation on the hyponychium (pigmentation of the cuticle) that is visible primarily with dermoscopy
- While this feature may be seen in some congenital nevi involving the nail unit, it is ass/w NAM in adults
- It needs to be underscored that in cases of NAM, a biopsy of the cuticle displaying the micro-Hutchinson’s sign may not necessarily reveal the underlying diagnosis
- while biopsy of the pigment in the cuticle may confirm the diagnosis of melanoma, a negative biopsy cannot be used to exclude melanoma in the matrix
how can dermoscopy of the free edge of the nail plate assist in determining whether is located in the proximal or distal nail matrix ?
- Histologically, proximal nail matrix is responsible for producing the keratin that forms the top surface of the nail plate
- distal nail matrix is responsible for producing the keratin that forms the undersurface of the nail plate
- Thus, pigmentation localized to the upper part of the nail´s free edge correlates with melanocytic proliferations located in the proximal portion of the nail matrix
- pigmentation of the lower part of the nail´s free edge correlates histologically with melanocytes proliferating distally in the nail matrix
Direct dermoscopy of the nail matrix reveals four dermoscopic patterns
dermoscopic sctructures with high specificity for non-melanoma neoplasms
