Diagnostic accuracy

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Diagnostic accuracy

Specificity and sensitivity

The majority of studies which have evaluated the diagnostic accuracy of dermoscopyDermoscopy is a non invasive diagnostic method. have relied on calculation of specificity and sensitivity, by comparing the diagnosisThis glossary term has not yet been described. made by dermoscopy with the histopathological diagnosis.

  • Specificity: the proportion of benignThis glossary term has not yet been described. pigmented skin lesions that are correctly identified by dermoscopy
  • Sensitivity: the proportion of melanomas that are correctly identified by dermoscopy

Advantages and Disadvantages

Advanages
  • Valid indicators of diagnostic testThis glossary term has not yet been described. performance
  • Easily understood
Disadvanages

The diagnosis made by dermoscopy has to be divided into two groups: benign and malignantThis glossary term has not yet been described.. This is surely an oversimplification of the diagnostic procedure of dermoscopy.

DermoscopyDermoscopy is a non invasive diagnostic method. is a tool to minimize uncertainty, thus aiming to the correct interpretation of a dermoscopic finding and leading to a decision of the necessity of further diagnostic procedures (excision). However, the interpretation of the dermoscopic findings is also influenced by other variables:

  • Clinical impression of the lesion
  • Ageprocess of becoming older of the patient
  • Anatomic side
  • Number and appearance of other lesions on the same patient

Other disadvantages to the evaluation of diagnostic tests by their sensitivity and specificity include the prevalence of the disease of interest (in this case melanomaThis glossary term has not yet been described.) not being taken into account, and the difficulties of comparing two diagnostic tests.

Diagnostic accuracy factors

The diagnostic accuracy of dermoscopy depends on many factors:

Level of training of dermatologists

The diagnostic accuracy of dermoscopy depends on the level of experience of the observer, as when applied by non experts is in fact worse than the diagnostic accuracy achieved without dermoscopy.[1] The diagnostic accuracy of primary care physicians simnifically improved after teaching of dermoscopy. [2]

Diagnostic difficulty of the evaluated lesions

There is overwhelming evidence confirming, that dermoscopy improves the diagnostic accuracy for melanoma in comparison to inspection with unaided eye.

Type of algorithmIn mathematics and computer science, an algorithm (Listeni/ˈælɡərɪðəm/ AL-gə-ri-dhəm) is a self-contained sequence of actions to be performed. Algorithms can perform calculation, data processing and automated reasoning tasks. used to evaluate the lesions

  • Pattern analysis[3]
  • ABCD rule[4]
  • SevenThis glossary term has not yet been described. pointThis glossary term has not yet been described. checklistThis glossary term has not yet been described.[5]
  • Menzies and associates algorithm[6]

A number of diagnostic algorithms have been developed for the dermoscopic evaluation of pigmented lesions. Pattern analysis has been shown to have a higher specificity than the other algorithms, but no significant differences were found with regard to sensitivity.[7]

References

  1. An Atlas of Dermoscopy, Second Edition. Marghoob A. et al. CRC Press; 2012.
  2. Benelli C, Roscetti E, Pozzo VD, et al. The dermo- scopic versus the clinical diagnosis of melanoma. Eur J Dermatol 1999;9:470-6
  3. Binder M, Schwarz M, Winkler A, et al. Epiluminescence microscopy. A useful tool for the diagnosis of pigmented skin lesions for formally trained dermatologists. Arch Dermatol 1995; 131:286-91
  4. Binder M, Puespoeck-Schwarz M, Steiner A, et al. Epiluminescence microscopy of small pigmented skin lesions: short-term formal training improves the diagnostic performance of dermatologists. J Am Acad Dermatol 1997;36:197-202
  5. Carli P, De Giorgi,V, Naldi L, Dosi G. Reliability and inter-observer agreement of dermoscopic diagnosis of melanoma and melanocyticThis glossary term has not yet been described. naevi. Dermoscopy Panel. Eur J Cancer Prev 1998;7:397-402
  6. Cristofolini M, Zumiani G, Bauer P, et al. Dermato- scopy: usefulness in the differential diagnosis of cuta- neous pigmentary lesions.MelanomaThis glossary term has not yet been described. Res 1994; 4:391-4
  7. Dummer W, Doehnel KA, Remy W. Videomicroscopy in differential diagnosis of skin tumors and secondary prevention of malignant melanoma. Hautarzt 1993;44:772-6
  8. Krähn G, Gottlober P, Sander C, Peter RU. DermatoscopyThis glossary term has not yet been described. and high frequency sonography: two useful non-invasive methods to increase preoperative diagnostic accuracy in pigmented skin lesions. Pigment Cell Res 1998;11:151-4
  9. Lorentzen H, Weismann K, Petersen CS, et al. Clinical and dermatoscopic diagnosis of malignant melanoma. Assessed by expert and non-expert groups. Acta Derm Venereol 1999;79:301-4
  10. Nachbar F, Stolz W, Merkle T, et al. The ABCD rule of dermatoscopyThis glossary term has not yet been described.. High prospective value in the diagnosis of doubtful melanocytic skin lesions. J Am Acad Dermatol 1994;30:551-9
  11. Soyer HP, Smolle J, Leitinger G, et al. Diagnostic reliability of dermoscopic criteriaThis glossary term has not yet been described. for detecting malig- nant melanoma. Dermatology 1995;190: 25-30 11.
  12. Stanganelli I, Serafini M, Cainelli T, et al. Accuracy of epiluminescence microscopy among practical dermatologists: a study from the Emilia-Romagna region of Italy. Tumori 1998;84:701-5
  13. Stanganelli I, Serafini M, Bucch L. A cancer-registry-assisted evaluation of the accuracy of digital epiluminescence microscopy associated with clinical exami- nation of pigmented skin lesions. Dermatology 2000;200:11-16
  14. Westerhoff K, McCarthy WH, Menzies SW. Increase in the sensitivity for melanoma diagnosis by primary care physicians using skin surface microscop. Br J Dermatol 2000;143:1016-20
  15. Kittler H, Pehamberger H, Wolff K, Binder M. Diagnostic accuracy of dermoscopy. Lancet Oncol 2002;3:159-65
  16. Mayer J. Systematic review of the diagnostic accuracy of dermatoscopy in detecting malignant melanoma. Med J Aust 1997;167:206-10
  17. Bafounta ML, Beauchet A, Aegerter P, Saiag P. Is dermoscopy (epiluminescence microscopy) useful for the diagnosis of melanoma? Results of a meta-analysis using techniques adapted to the evaluation of diagnostic tests. Arch Dermatol 2001;137:1343-50
  18. Vestergaard ME, Macaskill P, Holt PE, Menzies SW. Dermoscopy compared with naked eye examination for the diagnosis of primary melanoma: a meta-analysis of studies performed in a clinical setting. Br J Dermatol. 2008 Sep;159(3):669-76.
  19. Pehamberger H, Steiner A, Wolff K. In vivo epilumi- nescence microscopy of pigmented skin lesions. I. Pattern analysis of pigmented skin lesions. J Am Acad Dermatol 1987;17:571-83
  20. Stolz W, Riemann A, Armand B, et al. ABCD rule of dermatoscopy: a new practical method for early recognition of melanoma. Eur J Dermatol 1994;7: 521-7
  21. Argenziano G, Fabbrocini G, Carli P, et al. Epiluminescence microscopy for the diagnosis of doubtful melanocytic skin lesions. Comparison of the ABCD rule of dermatoscopy and a new 7-point checklist based on pattern analysis. Arch Dermatol 1998;134:1563-70
  22. Menzies SW, Ingvar C, Crotty KA, McCarthy WH. Frequency and morphologic characteristics of inva- sive melanomas lacking specific surface microscopic features. Arch Dermatol 1996;132:1178-82
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