The Triage Amalgamated Dermoscopy Algorithm (TADA) can be utilized to guide the management decision for isolated lesions in a skin cancer triage setting. The TADA algorithm has been tested by clinicians and nurse practitioners for the identification of cutaneous malignancy and has demonstrated a sensitivity of 94% and a specificity of 72% .
The dermoscopic features that the observer needs to be able to identify to effectively use TADA include determining whether or not the lesion has (Figure):
- Unequivocal clinical and dermoscopic features of seborrheic keratosis, dermatofibroma or angioma.
- Colors and structures distributed in an organized or disorganized pattern. Lesions with colors and structures distributed in an organized (low degree of entropy) manner are considered organized. Lesions with colors and structures distributed in an asymmetric, chaotic, or random manner (high degree of entropy) are considered disorganized.
- Starburst pattern.
- Blue-black or gray color.
- Shiny white structures (N.B. to see this structure requires the use of polarized dermoscopy!).
- Negative network.
- Any vascular structures or ulceration.
Determine whether the lesion is clinically and dermoscopically an unequivocal seborrheic keratosis, angioma, or dermatofibroma. Experienced clinicians can also recognize other less common benign lesions with certainty including sebaceous hyperplasia, clear cell acanthoma, and intradermal nevus. If the lesion is considered to be an unequivocal benign lesion, the patient can be reassured and no further evaluation is required. If the lesion does not manifest a classic pattern consistant with one of the aforementioned benign lesions then one needs to move to the next step in the TADA.
Step-2 is reserved for lesions in which the diagnosis of a benign neoplasm is not certain. These lesions are examined to determine if they display a dermoscopically organized or disorganized pattern. Dermoscopically disorganized lesions should be considered suspicious and either biopsied or referred to an expert for management. Dermoscopic asymmetry (i.e. chaotic or disorganized distribution of colors and structures) is one of the most important and most reproducible (with high interobserver agreement) feature to help differentiate benign from malignant tumors . Lesions that display an organized pattern move on to the last step in the TADA.
Only lesions considered to be dermoscopically organized (symmetric) will proceed to step-3. This step is designed to insure that skin cancers displaying an organized pattern do not escape detection. The features that help in the detection of skin cancers manifesting an organized pattern are:
- Starburst pattern: Given the unresolved controversy as to the most appropriate management of spitzoid neoplasms, all lesions manifesting a starburst-like pattern, which can be seen in Spitz/Reeds nevi and occasionally in melanoma, should be considered suspicious, especially in older individuals.
- Blue-black or gray color: The presence of blue-black color in a symmetric organized lesion should raise concern for nodular melanoma . Gray color has also been shown to be an important clue for skin cancer . Thus, symmetric lesions with a blue-black or gray color are considered suspicious in the TADA.
- Shiny white structures or negative network: Shiny white structures including white lines, blotches, strands and rosettes are seen only with polarized light. In contrast, negative network and white circles can be seen with both polarized and non-polarized light. The presence of any of these structures in an otherwise symmetric lesion should raise concern for malignancy .
- Vascular structures or ulceration: Symmetric lesions revealing vascular structures such as dotted vessels, serpentine vessels, glomerular vessels, milky red globules, or arborizing vessels should raise concern for skin cancer. Lastly, any lesion that is ulcerated should raise suspicion for malignancy.
In summary, any dermoscopically disorganized lesion that is not an unequivocal seborrheic keratosis, angioma or dermatofibroma should be considered suspicious for malignancy. Any dermoscopically organized lesion with a starburst pattern, blue-black-gray color, shiny white structures, negative network, vessels or ulceration should raise suspicion for malignancy. If the lesion is dermoscopically organized and does not reveal a starburst pattern, blue-black-gray color, shiny white structures, negative network, vessels or ulceration it can be monitored.
NB: In addition, volar lesions with a parallel ridge pattern and any changing lesion in an adult patient should also be considered suspicious.
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