Biomedical subjects

A B Cognetta

Publications and source records attributed to A B Cognetta.

4 recordsLinked to original sources

PubMed2001

Dermatoscopy of lentigo maligna.

Lentigo maligna and LMM require different dermatoscopic criteria for evaluation. The ease and accessibility of examining these lesions with dermatoscopy coupled with the clinical pathologic correlation afforded by the biopsy techniques discussed allow the practitioner to become proficient and prescient with the use of dermatoscopy. The criteria mentioned here are relatively new but are present and detectable in most cases of LM and LMM. The fact that there is some overlap among pigmented actinic keratosis, squamous cell carcinoma in situ, and lichenoid keratosis lesions should not detract or deter the physician from using dermatoscopy. Clinically, these lesions also usually will be equivocal and will require close clinical scrutiny and biopsies. If given the choice of using skin surface microscopy for one class of lesion only, one might well choose LM lesions because of their otherwise subtle nature and the clues that can be unlocked with oil immersion, illumination, and magnification, along with knowledge of these new criteria.

Dermatology↗

PubMed2000

Improvement of early recognition of lentigo maligna using dermatoscopy.

BACKGROUND: The clinical differentiation between lentigo senilis/initial seborrheic keratosis and lentigo maligna on the face can be difficult. OBJECTIVE: Our purpose was to determine whether dermatoscopy (eg, skin surface microscopy at 10x magnification) can reliably differentiate between these entities. METHODS: Dermatoscopic slides of 87 consecutive patients presenting 37 malignant and 50 benign pigmented skin lesions on the face were analyzed with the use of 27 dermatoscopic criteria. RESULTS: Univariate analysis selected two criteria specific for lentigo maligna: asymmetric pigmented follicular openings and dark (brown or black) rhomboidal structures. Location-specific importance in relation to facial location was attributed to the color "slate-gray, " especially in combination with structures such as dots, globules, streaks, and homogeneous areas. Multivariate analysis (logistic regression model) revealed the 4 most important features to be asymmetric pigmented follicular openings, dark rhomboidal structures, slate-gray globules, and slate-gray dots with a sensitivity of 89% and a specificity of 96%. CONCLUSION: Three conclusions can be drawn from our study: With a set of 4 dermatoscopic features, early lentigo maligna can be detected with high accuracy; dermatoscopic features on the face differ from criteria used in other locations; and our progression growth model for lentigo maligna delineates the different steps of malignant growth in lentigo maligna.

Analysis of Variance↗

PubMed1994

The ABCD rule of dermatoscopy. High prospective value in the diagnosis of doubtful melanocytic skin lesions.

BACKGROUND: The difficulties in accurately assessing pigmented skin lesions are ever present in practice. The recently described ABCD rule of dermatoscopy (skin surface microscopy at x10 magnification), based on the criteria asymmetry (A), border (B), color (C), and differential structure (D), improved diagnostic accuracy when applied retrospectively to clinical slides. OBJECTIVE: A study was designed to evaluate the prospective value of the ABCD rule of dermatoscopy in melanocytic lesions. METHODS: In 172 melanocytic pigmented skin lesions, the criteria of the ABCD rule of dermatoscopy were analyzed with a semiquantitative scoring system before excision. RESULTS: According to the retrospectively determined threshold, tumors with a score higher than 5.45 (64/69 melanomas [92.8%]) were classified as malignant, whereas lesions with a lower score were considered as benign (93/103 melanocytic nevi [90.3%]). Negative predictive value for melanoma (True-Negative divided by [True-Negative+False-Negative]) was 95.8%, whereas positive predictive value (True-Positive divided by [True-Positive+False-Positive]) was 85.3%. Diagnostic accuracy for melanoma (True-Positive divided by [True-Positive+False-Positive+False-Negative]) was 80.0%, compared with 64.4% by the naked eye. Melanoma showed a mean final dermatoscopy score of 6.79 (SD, +/- 0.92), significantly differing from melanocytic nevi (mean score, 4.27 +/- 0.99; p < 0.01, U test). CONCLUSION: The ABCD rule can be easily learned and rapidly calculated, and has proven to be reliable. It should be routinely applied to all equivocal pigmented skin lesions to reach a more objective and reproducible diagnosis and to obtain this assessment preoperatively.

Dermatology↗

PubMedDate not supplied

Techniques for a structural analysis of dermatoscopic imagery.

Techniques were developed for automated detection and characterization of dermatoscopic structures, including the pigment network and brown globules. These techniques incorporate algorithms for grayscale shape extraction based on differential geometry developed by Steger, a snake algorithm, and a modification of the region competition strategy of Zhu and Yuille. A novel approach was developed for global segmentation of pigmented lesions, based on stabilized inverse diffusion equations. Procedures for detection of air bubbles and hairs in dermatoscopic images are also reported.

Air↗