Hong Kong J. Dermatol. Venereol. (2013) 21, 181-187

TTTTTokyo Wokyo Wokyo Wokyo Wokyo Women's Medical University Medical Centeromen's Medical University Medical Centeromen's Medical University Medical Centeromen's Medical University Medical Centeromen's Medical University Medical CenterEast, JapanEast, JapanEast, JapanEast, JapanEast, Japan

M Tanaka, MD, PhD

Correspondence to: Professor M Tanaka

Tokyo Women's Medical University Medical Center East,2-1-10 Nishi-Ogu, Arakawa-ku, Tokyo 116-8567, Japan

In this second part of the review, the basic variations of parallel pattern in acral melanocyticlesions will be discussed. The relation between parallel pattern and dermatopathology will beelaborated. Finally, the second step of the 2-step procedure will be presented to illustrate howto judge whether the lesion is malignant or benign based on the distribution of colours andstructures.

Keywords:Keywords:Keywords:Keywords:Keywords: Dermoscope, dermoscopy, melanocytic naevus, melanoma, pigment network

Review Article

Dermoscopy basics and melanocytic lesions (Part 2 of 2)

M Tanaka

Basic variations of parallel patternBasic variations of parallel patternBasic variations of parallel patternBasic variations of parallel patternBasic variations of parallel patternin acral melanocytic lesionsin acral melanocytic lesionsin acral melanocytic lesionsin acral melanocytic lesionsin acral melanocytic lesions

There are four basic dermoscopy patterns in acralmelanocytic lesions (Figure 17). The parallelfurrow pattern (Figure 18) consists of narrowpigmented parallel lines on the furrows. A lattice-like pattern (Figure 19) is composed of shorttransverse lines on the ridges in addition to parallel

furrow pattern. This variation is mainly observedin naevi on the arch area of the sole, whereepidermal rete ridges are shallow and transverseridges are prominent. The fibrillar pattern (Figure20) is displayed as pigmented lines obliquelycrossing the skin markings. This pattern isexclusively seen on the pressure areas of the soleof the foot. These three patterns are regular incolour and structure and are frequently seen inacral melanocytic naevi. Meanwhile, the parallelridge pattern is composed of broad pigmentedlines with irregular pigmentation (Figure 21), whichis almost exclusively detected in acral melanoma.

VVVVVariations of parallel furrow patternariations of parallel furrow patternariations of parallel furrow patternariations of parallel furrow patternariations of parallel furrow pattern

Variations of the parallel furrow pattern (Figure22) include single line (Figure 18), single dotted

M Tanaka182

The crista reticulated variant tends to occur at theedge of the sole, where the shape of rete ridgestransitions from parallel to reticular pattern. Thetram-like variant is composed of broad doublelines along the furrows. The tram-like and finerparallel variants are extremely rare.

line (Figure 23), double line (Figure 24) anddouble dotted line variants (Figure 25). Furthervariations of the parallel furrow pattern (Figure26) include crista dotted (Figure 27), cristareticulated (Figure 28), tram-like (thick double line)(Figure 29) and finer parallel variants (Figure 30).

Figure 17. Figure 17. Figure 17. Figure 17. Figure 17. Basic dermoscopypatterns in acral melanocytic lesions.There are four basic dermoscopypatterns.

Figure 18. Figure 18. Figure 18. Figure 18. Figure 18. Parallel furrow pattern.Narrow pigmented parallel lines arepresent at the furrows. This casereveals single line variant of parallelfurrow pattern.

Figure 19. Figure 19. Figure 19. Figure 19. Figure 19. Lattice-like pattern.Transverse short lines on ridges areobserved in addition to parallelfurrow pattern. The pattern is moreoften observed in naevi on the archarea of the foot.

Figure 20. Figure 20. Figure 20. Figure 20. Figure 20. Fibrillar pattern. Narrowpigmented lines are obliquelycrossing skin markings. This patternis characteristic of naevi on thepressure areas of the sole.

Figure 21. Figure 21. Figure 21. Figure 21. Figure 21. Parallel ridge pattern.Broad pigmented parallel lineswith irregular pigmentation areexhibited on the ridges. This patterncorresponds to acral melanoma.

Figure 22. Figure 22. Figure 22. Figure 22. Figure 22. Variations of parallelfurrow pattern.There are fourvariants including single line, singledotted line, double line and doubledotted line variants.

Figure 23. Figure 23. Figure 23. Figure 23. Figure 23. Single dotted linevariant. Dark brown dots/globulesare arranged in a row on eachfurrow.

Figure 24. Figure 24. Figure 24. Figure 24. Figure 24. Double line variant. Twoparal le l p igmented l ines aredemonstrated on each furrow.

Figure 25. Figure 25. Figure 25. Figure 25. Figure 25. Double dotted linevariant. Dark brown dots/globulesare arranged in two rows on eachfurrow.

Dermoscopy basics 2 183

RRRRReason of parallel pattern aseason of parallel pattern aseason of parallel pattern aseason of parallel pattern aseason of parallel pattern aseeeeexplained by scanning electronxplained by scanning electronxplained by scanning electronxplained by scanning electronxplained by scanning electronmicroscopymicroscopymicroscopymicroscopymicroscopy

Now, wha t does t he pa ra l l e l pa t t e rnrepresent? The answer is also shown byscanning electron microscopy (Figure 31).

Figure 27. Figure 27. Figure 27. Figure 27. Figure 27. Crista dotted variant.Dark brown to blue-grey dots areseen on the centre of cristae often inaddition to parallel furrow pattern ofsingle line variant.

Figure 29. Figure 29. Figure 29. Figure 29. Figure 29. Tram-like variant. Thisvariation is a broader variant ofparallel furrow pattern with doubleline.

Figure 26. Figure 26. Figure 26. Figure 26. Figure 26. Further variations ofparallel furrow pattern. There arefurther variants of parallel furrowpattern including crista dotted, cristareticulated, tram-like and finerparallel pattern.

Figure 28. Figure 28. Figure 28. Figure 28. Figure 28. Crista reticulated variant.Reticular pattern is demonstrated incombination with parallel furrowpattern. This variant tends to occurat the edge of the sole.

Figure 30. Figure 30. Figure 30. Figure 30. Figure 30. Finer parallel pattern.This pattern consists of lines on thefurrows as well as lines on the centreof the ridges.

This figure displays the dermal side of theepidermis taken from the sole of the foot.There are two kinds of epidermal ridgesarranging alternatively. One is flat ridge andthe other is connected with dermal eccrineducts. The former is crista profunda (CP)limitans and the latter is CP intermedia.

Figure 31. Figure 31. Figure 31. Figure 31. Figure 31. Scanning electronmicroscopy of the epidermis fromacral skin. The epidermal rete ridgesfrom acral skin are illustrated asstructures arranged parallel to oneanother, which is equivalent toparallel pattern as seen in acralnaevus on dermoscopy (courtesy ofTetsuya Tsuchida, MD). One is flatridge and the other is connected withdermal eccrine ducts. The former iscrista profunda (CP) limitans and thelatter is CP intermedia.

M Tanaka184

The relation between parallelThe relation between parallelThe relation between parallelThe relation between parallelThe relation between parallelpattern and dermatopathologypattern and dermatopathologypattern and dermatopathologypattern and dermatopathologypattern and dermatopathology

When the acral skin specimen is cut perpendicularto skin markings, the configuration in Figure 32will be obtained. Comparing Figures 31 and 32helps us to understand the relationship betweenfurrow/ridge on dermoscopy and CP limitans/intermedia on dermatopathology, namely thefurrow corresponds to CP limitans and the ridgeto CP intermedia. Nests of naevus cells tend to bepresent either at CP limitans or intermedia andmatch up to parallel furrow pattern or crista dottedvariant. Individual cell proliferation of melanomais inclined to spread broadly and correspond tothe parallel ridge pattern.

The reason for the fibrillar patternThe reason for the fibrillar patternThe reason for the fibrillar patternThe reason for the fibrillar patternThe reason for the fibrillar pattern

Melanocytic lesions on weight-bearing areas showa fibrillar pattern (Figure 33). Short pigmentedlines are obliquely crossing the skin markings,which are noted as whitish dotted randomreflections at the furrows. If the specimen of thisnaevus is cut perpendicular to the skin markings,the H&E staining of the histopathology shows aslanting horny layer and melanin columns belowthe furrows, which correspond to nests ofmelanocytes at the cristae profundae limitans(Figure 34). This observation would be theexplanation of the fibrillar pattern.

The oblique view dermoscopyThe oblique view dermoscopyThe oblique view dermoscopyThe oblique view dermoscopyThe oblique view dermoscopy

The observation above is a hint of the obliqueview dermoscopy.6 The fibrillar pattern seen onnormal dermoscopy corresponds to the obliquemelanin columns viewed from the right aboveposition (Figure 35). An example of fibrillar patternreveals short pigmented lines obliquely crossingthe skin markings, more slanting at the right handside (Figure 36). Examination with dermoscopyof the same lesion at an oblique angle (Figure37), namely oblique view dermoscopy, will line

up the melanin columns and show up as a parallelfurrow pattern, single line variant (Figure 38).

The second step of the 2-The second step of the 2-The second step of the 2-The second step of the 2-The second step of the 2-stepstepstepstepstepprocedureprocedureprocedureprocedureprocedure

The second step is to judge if the lesion ismalignant or benign based on the distribution ofcolours and structures.

Firstly, the global features are assessed. Theyinclude reticular (Figure 39), globular (Figure 40),homogeneous (Figure 41), parallel (Figure 42),starburst (Figure 43), multi-component (Figure 44)and non-specific patterns (Figure 45). If twopatterns are observed, the dominant pattern ismentioned. If three patterns are mixed, it is themulti-component pattern. If no pattern is seen, itwill be regarded as non-specific. The former fivepatterns tend to be benign, though not necessarilyso, and could appear in early malignant lesions(Figure 46). On the other hand, the latter twopatterns are often found in melanoma, but notall.

Secondly, the local features are considered. Majorlocal features include pigment network, streaks,dots/globules, blue-whitish veil and regressionstructures. Typical and atypical networks aredistinguished, based on whether the network islight or dark, thin or thick, regularly or irregularlydistributed (Figures 47 & 48). A typical network isoften dim at the periphery (Figure 47) while anatypical pigment network often has an abruptedge (Figure 48). Streaks are defined as linearstructures at the periphery and histopathologicallycorrespond to the elongated nests of melanocytes.They might be regular or irregular in distribution.Dots/globules are defined as black, brown orblue-grey, round or oval structures with varioussizes and shapes with regular or irregulardistribution. Blue-whitish veil is defined asirregular and confluent blue-grey to blue-whitepigmentation. Regression structures are definedas white areas (scar-like white areas) or blue areas

Dermoscopy basics 2 185

Figure 32. Figure 32. Figure 32. Figure 32. Figure 32. The relation betweenparallel pattern and histopathology.CP limitans correspond to furrowsand CP intermedia, which isconnected with dermal eccrine ducts,to ridges.

F igure 33. F igure 33. F igure 33. F igure 33. F igure 33. Dermoscopy o fmelanocytic naevus on weight-bearing area. Dermoscopy showingregular fibrillar pattern.

Figure 34. Figure 34. Figure 34. Figure 34. Figure 34. Histopathology of anaevus showing fibrillar pattern.There are slanting horny layers andoblique melanin columns below thefurrows, which correspond to nestsof melanocytes at cristae profundaelimitans.

Figure 35. Figure 35. Figure 35. Figure 35. Figure 35. The reason of fibrillarpattern on ordinary dermoscopy.Ordinary dermoscopy observesoblique melanin columns from theright above position.

Figure 36. Figure 36. Figure 36. Figure 36. Figure 36. An example of fibrillarpattern. Ordinary dermoscopyreveals short pigmented l inesobliquely crossing skin markings.

Figure 37. Figure 37. Figure 37. Figure 37. Figure 37. Oblique viewing bydermoscopy. It is a change ofdirection of dermoscopy observation,namely oblique observation.

Figure 38. Figure 38. Figure 38. Figure 38. Figure 38. An example of obliqueview dermoscopy. It demonstratesparallel furrow pattern, single linevariant.

Figure 39. Figure 39. Figure 39. Figure 39. Figure 39. Reticular pattern. Clark'snaevus showing reticular pattern withtypical pigment network.

Figure 40. Figure 40. Figure 40. Figure 40. Figure 40. Globular pattern. Clark'snaevus showing globular patternwith regular dots/globules.

M Tanaka186

Figure 41. Figure 41. Figure 41. Figure 41. Figure 41. Homogeneous pattern.Blue naevus showing homogeneouspattern with blue pigmentation.

Figure 42. Figure 42. Figure 42. Figure 42. Figure 42. Parallel pattern. Acralnaevus showing parallel pattern withparallel furrow pattern of single linevariant.

Figure 43. Figure 43. Figure 43. Figure 43. Figure 43. Starburst pattern.Pigmented Spitz naevus (Reednaevus) showing starburst patternwith regular streaks.

Figure 44. Figure 44. Figure 44. Figure 44. Figure 44. Multi-componentpattern. Malignant melanomashowing multi-component patternwith atypical pigment network,i r regular dots/g lobules andstructureless pigmentation.

Figure 46. Figure 46. Figure 46. Figure 46. Figure 46. An early melanomain situ with the reticular pattern.Reticular pattern is usually thehallmark of Clark's naevus, but itmay be rarely demonstrated in anearly lesion of melanoma in-situ.

Figure 47. Figure 47. Figure 47. Figure 47. Figure 47. Typical pigment network.The pigment network in this Clark'snaevus is thin, brown and dim at theperiphery.

Figure 48. Figure 48. Figure 48. Figure 48. Figure 48. Atypical pigmentnetwork. The pigment network in thismelanoma is thick and dark at theperiphery, showing an abrupt edge.

Figure 45. Figure 45. Figure 45. Figure 45. Figure 45. Non-specific patterns.Seborrhoeic keratosis showing non-specific pattern.

Dermoscopy basics 2 187

(blue-grey areas, peppering and multiple blue-grey dots). White areas and blue areas togetherreflect the main aspects of regressions, namelyfibrosis and melanophages.

RRRRReferenceseferenceseferenceseferenceseferences

1. Nachbar F, Stolz W, Merkle T, Cognetta AB, Vogt T,Landthaler M, et al. The ABCD rule of dermatoscopy.High prospective value in the diagnosis of doubtfulmelanocytic skin lesions. J Am Acad Dermatol 1994;30:551-9.

2. Menzies SW, Ingvar C, Crotty KA, McCarthy WH.Frequency and morphologic characteristics ofinvasive melanomas lacking specif ic surfacemicroscopic features. Arch Dermatol 1996;132:

1178-82.3. Argenziano G, Fabbrocini G, Carli P, De Giorgi V,

Sammarco E, Delfino M. Epiluminescence microscopyfor the diagnosis of doubtful melanocytic skin lesions.Comparison of the ABCD rule of dermatoscopy and anew 7-point checklist based on pattern analysis. ArchDermatol 1998;134:1563-70.

4. Argenziano G, Soyer HP, Chimenti S, Talamini R,Corona R, Sera F, et al. Dermoscopy of pigmentedskin lesions: Results of a consensus meeting via theinternet. J Am Acad Dermatol 2003;48:679-93.

5. Soyer HP, Argenziano G, Chimenti S, Menzies SW,Pehamberger H, Rabinovitz HS, et al. Consensus netmeeting on dermoscopy 2000. Dermoscopy ofpigmented skin lesions. 1st edn. EDRA, Milano, 2001.

6. Maumi Y, Kimoto M, Kobayashi K, Ito N, Saida T,Tanaka M. Oblique view dermoscopy changes regularf ibri l lar pattern into parallel furrow pattern.Dermatology 2009;218:385-6.