Two step algorithm (melanocytic vs non-melanocytic) Flashcards
What is the main purpose of the 2-step algorithm?
Avoid missing the diagnosis of melanoma
Designed to maximize the sensitivity for melanoma detection
Limitations of the 2-step algorithm
Designed to evaluate lesions on glabrous & nonglabrous skin only
Not intended for evaluation of nail,mucosa, hair abnormalities
Algorithm for the differentiation btw melanocytic & nonmelanocytic lesions
1st step in 2-step algorithm
Decide whether a lesion is of melanocytic or nonmelanocytic origin
1st step is composed of how many levels?
7 levels
Each of which requires the
clinician to search for specific structures and criteria
Name the 7 decision levels of the first step
Criteria for
- Level 1: Melanocytic lesions
- Level 2: BCC
- Level 3: SKs
- Level 4: Vascular lesions
- Level 5: Specific blood vessels for nonmelanocytic neoplasms
- Level 6: Specific blood vessels for melanocytic lesions
- Level 7: Structureless
All lesions in level 7 are considered…?
Melanocytic by default
Melanoma needs to be considered in the DDx
2nd step in the 2-step algorithm
Determine whether the presumed melanocytic lesion from step 1
is benign, suspect, or malignant
Two-step procedure for the differential diagnosis of pigmented lesions
What does the 1st level of step 1 consist of?
Criteria for melanocytic lesions
- Pigment network
- branched streaks (e.g., atypical network)
- streaks (i.e., radial streaming and pseudopods)
- negative network
- aggregated globules
- homogenous blue pigmentation
- pseudonetwork (face)
- parallel pattern (palms, soles, and mucosa)
If any of the criteria in level 1 are met, what is the BNS?
Lesion is considered of melanocytic origin
Proceed directly to the 2nd step of the 2-step algorithm
Name one major exception of 1st level
Dermatofibroma
Delicate peripheral network with a central scar-like area
(as seen in NPD)
How to differentiate a blue nevus from other lesions
Blue-white veil that’s covers the ENTIRE lesion
in a HOMOGENOUS manner (NPD)
ps: in PD blue nevus reveal different shades or hues of blue
Describe the major dermoscopic finding in this lesion
Dx?
Typical regular pn (Level 1)
Thinning out toward the periphery
Junctional nevus
Describe the major dermoscopic finding in this lesion
Dx?
Atypical pn
Branched streaks
Dysplastic nevus
Describe the major dermoscopic finding in this lesion
Dx?
Globular architecture
multiple round & ovoid globules
Compound nevus
Describe the major dermoscopic finding in this lesion
Dx?
Homogenous blue veil pigmentation
that covers the ENTIRE lesion
Blue nevus
Describe the major dermoscopic finding in this lesion
Dx?
Typical regular pseudonetwork
Compound nevus of the face
Describe the major dermoscopic finding in this lesion
Dx?
Lattice-like pattern
variation of the parallel furrow pattern
Junctional nevus, palm
Describe the major dermoscopic finding in this lesion
Dx?
Irregular confluent bluish-whitish pigmentation
does NOT occupy the entire surface area of the lesion
Malignant melanoma
None of the criteria of level 1 are met, BNS?
Proceed to level 2
Criteria for BCC
Name the criteria for BCC
- Arborizing blood vessels (telangiectasias)
- Leaf-like areas
- Large blue-gray ovoid nests
- Multiple blue-gray non-aggregated globules
- Spoke-wheel-like structures
- Shiny white areas
- Ulceration
Condition under which, presence of level 2 criteria are ^ suggestive of BCC?
Absence of pigment network
NEVER SKIP level 1
Describe the major dermoscopic finding in this lesion
Dx?
Arborizing telangiectasia (arrows)
Ulceration (arrowheads)
Multiple leaf-like areas (asterisks)
pBCC
Describe the major dermoscopic finding in this lesion
Dx?
Multiple blue-gray ovoid nests (arrows)
Leaf-like areas
Telangiectasia (left part)
Nodular pBCC
Describe the major dermoscopic findings in this lesion
Dx?
Multiple blue-gray non-aggregated globules (arrows)
blue-gray ovoid nests
ulceration (asterisks)
arborized telan- giectasia (arrowheads)
pBCC
If none of the criteria of level 2 are met, BNS?
Proceed to level 3
Criteria for SKs
Name the criteria for SKs
- Multiple milia-like cysts
- Comedo-like openings
- Crypts
- Moth-eaten borders
- Network-like structures
- Fissures and ridges (aka gyri & sulci)
- Fingerprint-like structures
Does presence of milia cysts equate Dx of SK?
No
- DDx:
- SKs
- BCC
- Melanocytic nevi (especially congenital type)
If 2,3 are excluded then milia cysts are a diagnostic criterion
Describe the major dermoscopic finding in this lesion
Dx?
multiple milia- like cysts (arrows)
comedo-like openings (asterisks)
network-like structures (dotted areas) at the periphery
pSK