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. 2022 Jul 1;12(3):e2022123.
doi: 10.5826/dpc.1203a123. eCollection 2022 Jul.

Dermoscopy for Acral Melanocytic Lesions: Revision of the 3-step Algorithm and Refined Definition of the Regular and Irregular Fibrillar Pattern

Toshiaki Saida  1 , Hiroshi Koga  1 , Hisashi Uhara  2
Affiliations

Dermoscopy for Acral Melanocytic Lesions: Revision of the 3-step Algorithm and Refined Definition of the Regular and Irregular Fibrillar Pattern

Toshiaki Saida et al. Dermatol Pract Concept. .
No abstract available

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Conflict of interest statement

Competing interests: None.

Figures

Figure 1
Figure 1
The re-revised 3-step algorithm for the management of melanocytic lesions on acral volar skin. The main targets of this algorithm are macular/patch lesions seen in adults. Apparently congenital lesions and nodular lesions are excluded from the evaluation.
Figure 2
Figure 2
Regular fibrillar pattern of acral nevus (dermoscopy with the furrow ink test). (A) The fibrils constituting the pattern are regular in color, thickness and distribution. All the endpoints of the fibrils line up on the sulci of the skin markings. The pattern changes to the parallel furrow pattern in the lower portion. (B) The oblique dermoscopy reveals that this is originally the parallel furrow pattern.
Figure 2
Figure 2
Regular fibrillar pattern of acral nevus (dermoscopy with the furrow ink test). (A) The fibrils constituting the pattern are regular in color, thickness and distribution. All the endpoints of the fibrils line up on the sulci of the skin markings. The pattern changes to the parallel furrow pattern in the lower portion. (B) The oblique dermoscopy reveals that this is originally the parallel furrow pattern.
Figure 3
Figure 3
Irregular fibrillar pattern of acral melanoma in situ. This lesion of the multicomponent pattern is mostly composed of fibrils and can be regarded as the irregular FP by our definition, ie, the fibrils constituting the pattern are irregular in color, thickness and distribution, and their endpoints do not line up on the sulci of the skin markings. (A) Transition to the parallel ridge pattern is detected in the right lower portion. The negative fibrillar pattern (whitish rods arranged in a parallel fashion) are detected in the left area, which is well recognized in (B), an image of higher magnification corresponding to the square area in (A). (B) Arrows indicate some of the whitish rods.
Figure 3
Figure 3
Irregular fibrillar pattern of acral melanoma in situ. This lesion of the multicomponent pattern is mostly composed of fibrils and can be regarded as the irregular FP by our definition, ie, the fibrils constituting the pattern are irregular in color, thickness and distribution, and their endpoints do not line up on the sulci of the skin markings. (A) Transition to the parallel ridge pattern is detected in the right lower portion. The negative fibrillar pattern (whitish rods arranged in a parallel fashion) are detected in the left area, which is well recognized in (B), an image of higher magnification corresponding to the square area in (A). (B) Arrows indicate some of the whitish rods.
Figure 4
Figure 4
“Regular” fibrillar pattern seen in acral melanoma in situ (A, inset: clinical features: a brown patch, 13.5 × 10.5 mm in size, seen on the sole of a 78-year-old woman). (A) The very thin fibrils constituting this fibrillar pattern are evenly arranged and regular in color and thickness. (B) the square area in (A). The furrow ink test reveals that the sulci of the skin markings, indicated with arrows, are spared from the fibrillar pigmentation. (C, D) Histopathological features. (D) corresponds to the square area in (C). The thick cornified layer is obliquely arranged, as indicated with arrows in (C). The increased number of melanocytes are mainly detected in the crista profunda intermedia indicated with asterisks in (C) and their nuclei are large and hyperchromatic as seen in (D), confirming this is acral melanoma in situ. (Note: FISH analysis of this lesion revealed amplification of cyclin D1.)
Figure 4
Figure 4
“Regular” fibrillar pattern seen in acral melanoma in situ (A, inset: clinical features: a brown patch, 13.5 × 10.5 mm in size, seen on the sole of a 78-year-old woman). (A) The very thin fibrils constituting this fibrillar pattern are evenly arranged and regular in color and thickness. (B) the square area in (A). The furrow ink test reveals that the sulci of the skin markings, indicated with arrows, are spared from the fibrillar pigmentation. (C, D) Histopathological features. (D) corresponds to the square area in (C). The thick cornified layer is obliquely arranged, as indicated with arrows in (C). The increased number of melanocytes are mainly detected in the crista profunda intermedia indicated with asterisks in (C) and their nuclei are large and hyperchromatic as seen in (D), confirming this is acral melanoma in situ. (Note: FISH analysis of this lesion revealed amplification of cyclin D1.)
Figure 4
Figure 4
“Regular” fibrillar pattern seen in acral melanoma in situ (A, inset: clinical features: a brown patch, 13.5 × 10.5 mm in size, seen on the sole of a 78-year-old woman). (A) The very thin fibrils constituting this fibrillar pattern are evenly arranged and regular in color and thickness. (B) the square area in (A). The furrow ink test reveals that the sulci of the skin markings, indicated with arrows, are spared from the fibrillar pigmentation. (C, D) Histopathological features. (D) corresponds to the square area in (C). The thick cornified layer is obliquely arranged, as indicated with arrows in (C). The increased number of melanocytes are mainly detected in the crista profunda intermedia indicated with asterisks in (C) and their nuclei are large and hyperchromatic as seen in (D), confirming this is acral melanoma in situ. (Note: FISH analysis of this lesion revealed amplification of cyclin D1.)
Figure 4
Figure 4
“Regular” fibrillar pattern seen in acral melanoma in situ (A, inset: clinical features: a brown patch, 13.5 × 10.5 mm in size, seen on the sole of a 78-year-old woman). (A) The very thin fibrils constituting this fibrillar pattern are evenly arranged and regular in color and thickness. (B) the square area in (A). The furrow ink test reveals that the sulci of the skin markings, indicated with arrows, are spared from the fibrillar pigmentation. (C, D) Histopathological features. (D) corresponds to the square area in (C). The thick cornified layer is obliquely arranged, as indicated with arrows in (C). The increased number of melanocytes are mainly detected in the crista profunda intermedia indicated with asterisks in (C) and their nuclei are large and hyperchromatic as seen in (D), confirming this is acral melanoma in situ. (Note: FISH analysis of this lesion revealed amplification of cyclin D1.)
Figure 5
Figure 5
Regular fibrillar pattern composed of thick fibrils. A small brown macule, 4 mm in diameter, seen on the sole of a 38-year-old woman. This fibrillar pattern is composed of regularly arranged thick fibrils, of which endpoints line up on the sulci of the skin markings. Although the color density of the fibrils is somewhat different within the lesion, the color distribution is mostly symmetric, indicating this is the regular FP. From these findings, we can certainly diagnose this lesion as acral nevus. Note: These thick fibrils indicate that melanocytes in the epidermis are not distributed as solitary units but arranged mostly in larger nests, which is an important histopathologic clue to benign nevus of a small size such as this one (4mm).
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