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Diagnostic accuracy in cases of skin lesions
Letters
[6] [7]
[8] [9]
Herrmann KL, et al. (Eds.), 5th Edn., Washington: American Society for Microbiology 1992;277-286. Temple DE, Boardman CR. The incidence of erythrasma of the toewebs. Arch Dermatol 1962;86:518-519. Serdaroglu S, &imen A, &bayram H, Tcziin Y. Ayak parmak arasl enfeksiyonlannda wood q@mm tamsal degeri. Deri Hast Frengi Ar$ 1988;22:37-42. Karaman A. Hastanede yatan hastalarm ayagmda mikolojik Galqma. Deri hast Frengi Aq 1982;16:69-72. Somerville DA. Erythrasma in normal young adults. J Med Microbial 1970;3:57-64.
Diagnostic
accuracy
in cases of skin lesions
To the Editor: Methods for verifying the accuracy of clinical diagnosis are of primary importance for improvement of dermatologic knowledge. Until now, studies performed have considered only some types of lesions [1,2] but there is little or limited information about skin lesions as a whole. We have evaluated the accuracy of the clinical diagnosis in 3572 cases of skin lesions, the frequency of Correct and Incorrect diagnosis, in the attempt to detect criteria, if possible, for mistakes for different groups of skin lesions. The methods used were those reported by Lightstone [3], and diagnoses were divided into Correct positive (A): a clinically diagnosed lesion, histologically confirmed as the same; Incorrect positive (B): a lesion for which clinical diagnosis was not histologically confirmed; Incorrect negative CC): a lesion for which histological diagnosis was different from the clinical diagnosis. We evaluated the Diagnostic Accuracy = A X 100/A + B + C and the Index of Suspicion (Z,S) = Clinical Incidence (A + B) X lOO/Actual Incidence (A + C) in all cases.The 3572 skin lesionswere diagnosedby a stable staff of three specialists; only a single diagnosis, the most likely, was permitted. The clinical impression was verified by microscopic findings, the final diagnosis was based on the histopathology. The results are summarized in Table 1 with particular attention to the incorrect clinical diagnosesof somevery significant lesions. Any clinical diagnosis in dermatology may be difficult, but our own casesdemonstrate that some types of lesions are more difficult to diagnose than others. Our personal experience does not claim to represent the state of the art but only to provide
to the Editor [lo]
Sarkany I, Taplin D, Blank H. The etiology and treatment erythrasma. J Invest Dermatol 1961;37:283-288.
* Corresponding author. This paper was presented at the Third September 1993, Copenhagen, Denmark.
EADV
Congress,
of
26-30
SSDI 0926-9959(94)00016-X
somefurther information on this topic. The concepts of diagnostic accuracy (DA) and index of suspicion (IS) are useful but a more important aspect in the clinical diagnosis of skin lesions is the analysis of Incorrect diagnosis. Such analysis demonstratesthat histopathologic examination should not be dispensed with for all apparently easy to identify lesions. In fact, as well emphasized by Fiadero [4], the risks are overtreatment, under or ineffective treatment or fortuitous treatment. The concept of IS addressesthe question of underdiagnosisor over diagnosis.Some “easy” or not specific or “common” skin lesionscan give a great number of possibilities of misdiagnosiswith serious practical consequences.As Grin pointed out [2], it would be preferable, especially for a suspectedskin tumor, to have an overdiagnosis (IS > 100). Diagnostic skill is the fundamental basis for appropriate care in several dermatoses,especially in the preoperative phasein casesrequiring surgical therapy. Multiple variables interfere in the correct clinical diagnosis: the level of training of the physician, the nosological entity of the lesion in question, the possibly changing feature of a lesion. Recently Norman [5] stated that diagnostic errors are not predictable on the basis of stable characteristics or changing features of lesions. Thus, we think that further and more detailed studies on DA and related problems could lead to significant improvement in the diagnostic skill exercised in all departmentsof dermatology. R. Betti
* , E. Inselvini,
Clinica Dermatologica 20142 Milano, Italy
A. Lodi,
IV, Ospedale
C. Crosti
sari Paolo,
Via di Rudiini
8,
Letters Table 1 Diagnostic Clinical
Accuracy Diagnosis
(DA),
Index n
of Suspicion
(IS),
Incorrect
to the Editor
Positive
(IP)
and Incorrect
DA
IS
IP
Basal cell cart.
756
85.1
105
adnexal neoplasm seborrheic keratoses sebaceous hyperplasia other
Pigmented
690
95.4
101
seborrheic keratoses basal cell carcinomas other
naevi
Nevocytic
naevi
615
88.0
Seborrheic
kerat.
233
53.5
76
Adnexal
Dermatofibromas Angiomas Keratoacanthoma Pyogenic granul. Kaposi’s sarcoma Lichenoid dermat. Lupus erithemat. Actinic keratosis Blue naevi Melanomas Lymphomas Annular granuloma Chondrodermatitis Epithelial naevi Sebaceous naevi Warts Squamous epithel. Bowen disease Epidermoid cysts Lipomas Bullous diseases Other TOTALS: IP: clinical diagnosis.
24 22
of skin lesions
28 4 12
seborreheic keratoses dermatofibromas other
75.9
nevocytic naevi actinic keratoses other
38.3
49.3
sebaceous hyperplasia nevus sebaceous other
149 97 51 50 37 70 57 46 42 37 19 32
75.6 84.0 67.2 90.9 84.6 85.5 83.8 65.4 90.6 74.3 69.5 78.3
93.2 111.4 100 98.1 94.5 101 105.2 97.8 95.2 83.1 89.4 106.2
23 43 20 33 39 39 42 19 48 209
95.8 67.2 51.8 47.0 48.8 53.8 97.6 89.4 71.6
104.3 113.9 105.0 127.2 56.4 105.1 102.4 105.8 101.7
neither
Diagnosis
Bowen disease nevocytic naevi seborrheic keratoses other
24
11
13
seborrheic keratoses dermatofibromas other
14 5 15
epithelial naevi basal cell carcinomas other
19 16 55 20
0
basal cell carcinomas warts other
nor negated
17
13 25 13 10 3 4
10 2 2 6 7 9
4 10
2 5
18 6 13 1
0 6 6 9 17 11 0
10
9
12
316 confirmed
2 5
15
3572 diagnosis
(IN) IN
seborrheic keratoses basal cell carcinomas other
neoplasms
101
Negative
by histological
[1] Presser SE, Taylor R. Clinical diagnostic accuracy of basal cell carcinoma .I Am Acad Dermatol 1987;16:988-990. [2] Grin CM, Kopf AW, Welkovich B, Bart RS, Levenstein MJ. Accuracy in the clinical diagnosis of malignant melanoma. Arch Dermatol 1990;126:763-766 [3] Lightstone AC, Kopf AW, Garfinkel L. Diagnostic accuracy-A new approach to its evaluation. Results in basal cell carcinomas. Arch Dermatol 1965;91:497-502. [4] Fiadeiro T, Tavares Bello RC, Feio A, Fernandes Rodrigues
findings;
IN:
histopathological
363 diagnosis
different
from
clinical
JC. Basal-cell carcinoma: diagnostic accuracy (1988-1989) Skin Cancer 1991;6:9-13. [5] Norman GR, Rosenthal D, Brooks LR, Allen SW, Muzzin LJ. The development of expertise in dermatology. Arch Dermatol 1989;125:1063-1068.
* Corresponding
author.
SSDI 0926-9959(94)00023-2
[6] [7]
[8] [9]
Herrmann KL, et al. (Eds.), 5th Edn., Washington: American Society for Microbiology 1992;277-286. Temple DE, Boardman CR. The incidence of erythrasma of the toewebs. Arch Dermatol 1962;86:518-519. Serdaroglu S, &imen A, &bayram H, Tcziin Y. Ayak parmak arasl enfeksiyonlannda wood q@mm tamsal degeri. Deri Hast Frengi Ar$ 1988;22:37-42. Karaman A. Hastanede yatan hastalarm ayagmda mikolojik Galqma. Deri hast Frengi Aq 1982;16:69-72. Somerville DA. Erythrasma in normal young adults. J Med Microbial 1970;3:57-64.
Diagnostic
accuracy
in cases of skin lesions
To the Editor: Methods for verifying the accuracy of clinical diagnosis are of primary importance for improvement of dermatologic knowledge. Until now, studies performed have considered only some types of lesions [1,2] but there is little or limited information about skin lesions as a whole. We have evaluated the accuracy of the clinical diagnosis in 3572 cases of skin lesions, the frequency of Correct and Incorrect diagnosis, in the attempt to detect criteria, if possible, for mistakes for different groups of skin lesions. The methods used were those reported by Lightstone [3], and diagnoses were divided into Correct positive (A): a clinically diagnosed lesion, histologically confirmed as the same; Incorrect positive (B): a lesion for which clinical diagnosis was not histologically confirmed; Incorrect negative CC): a lesion for which histological diagnosis was different from the clinical diagnosis. We evaluated the Diagnostic Accuracy = A X 100/A + B + C and the Index of Suspicion (Z,S) = Clinical Incidence (A + B) X lOO/Actual Incidence (A + C) in all cases.The 3572 skin lesionswere diagnosedby a stable staff of three specialists; only a single diagnosis, the most likely, was permitted. The clinical impression was verified by microscopic findings, the final diagnosis was based on the histopathology. The results are summarized in Table 1 with particular attention to the incorrect clinical diagnosesof somevery significant lesions. Any clinical diagnosis in dermatology may be difficult, but our own casesdemonstrate that some types of lesions are more difficult to diagnose than others. Our personal experience does not claim to represent the state of the art but only to provide
to the Editor [lo]
Sarkany I, Taplin D, Blank H. The etiology and treatment erythrasma. J Invest Dermatol 1961;37:283-288.
* Corresponding author. This paper was presented at the Third September 1993, Copenhagen, Denmark.
EADV
Congress,
of
26-30
SSDI 0926-9959(94)00016-X
somefurther information on this topic. The concepts of diagnostic accuracy (DA) and index of suspicion (IS) are useful but a more important aspect in the clinical diagnosis of skin lesions is the analysis of Incorrect diagnosis. Such analysis demonstratesthat histopathologic examination should not be dispensed with for all apparently easy to identify lesions. In fact, as well emphasized by Fiadero [4], the risks are overtreatment, under or ineffective treatment or fortuitous treatment. The concept of IS addressesthe question of underdiagnosisor over diagnosis.Some “easy” or not specific or “common” skin lesionscan give a great number of possibilities of misdiagnosiswith serious practical consequences.As Grin pointed out [2], it would be preferable, especially for a suspectedskin tumor, to have an overdiagnosis (IS > 100). Diagnostic skill is the fundamental basis for appropriate care in several dermatoses,especially in the preoperative phasein casesrequiring surgical therapy. Multiple variables interfere in the correct clinical diagnosis: the level of training of the physician, the nosological entity of the lesion in question, the possibly changing feature of a lesion. Recently Norman [5] stated that diagnostic errors are not predictable on the basis of stable characteristics or changing features of lesions. Thus, we think that further and more detailed studies on DA and related problems could lead to significant improvement in the diagnostic skill exercised in all departmentsof dermatology. R. Betti
* , E. Inselvini,
Clinica Dermatologica 20142 Milano, Italy
A. Lodi,
IV, Ospedale
C. Crosti
sari Paolo,
Via di Rudiini
8,
Letters Table 1 Diagnostic Clinical
Accuracy Diagnosis
(DA),
Index n
of Suspicion
(IS),
Incorrect
to the Editor
Positive
(IP)
and Incorrect
DA
IS
IP
Basal cell cart.
756
85.1
105
adnexal neoplasm seborrheic keratoses sebaceous hyperplasia other
Pigmented
690
95.4
101
seborrheic keratoses basal cell carcinomas other
naevi
Nevocytic
naevi
615
88.0
Seborrheic
kerat.
233
53.5
76
Adnexal
Dermatofibromas Angiomas Keratoacanthoma Pyogenic granul. Kaposi’s sarcoma Lichenoid dermat. Lupus erithemat. Actinic keratosis Blue naevi Melanomas Lymphomas Annular granuloma Chondrodermatitis Epithelial naevi Sebaceous naevi Warts Squamous epithel. Bowen disease Epidermoid cysts Lipomas Bullous diseases Other TOTALS: IP: clinical diagnosis.
24 22
of skin lesions
28 4 12
seborreheic keratoses dermatofibromas other
75.9
nevocytic naevi actinic keratoses other
38.3
49.3
sebaceous hyperplasia nevus sebaceous other
149 97 51 50 37 70 57 46 42 37 19 32
75.6 84.0 67.2 90.9 84.6 85.5 83.8 65.4 90.6 74.3 69.5 78.3
93.2 111.4 100 98.1 94.5 101 105.2 97.8 95.2 83.1 89.4 106.2
23 43 20 33 39 39 42 19 48 209
95.8 67.2 51.8 47.0 48.8 53.8 97.6 89.4 71.6
104.3 113.9 105.0 127.2 56.4 105.1 102.4 105.8 101.7
neither
Diagnosis
Bowen disease nevocytic naevi seborrheic keratoses other
24
11
13
seborrheic keratoses dermatofibromas other
14 5 15
epithelial naevi basal cell carcinomas other
19 16 55 20
0
basal cell carcinomas warts other
nor negated
17
13 25 13 10 3 4
10 2 2 6 7 9
4 10
2 5
18 6 13 1
0 6 6 9 17 11 0
10
9
12
316 confirmed
2 5
15
3572 diagnosis
(IN) IN
seborrheic keratoses basal cell carcinomas other
neoplasms
101
Negative
by histological
[1] Presser SE, Taylor R. Clinical diagnostic accuracy of basal cell carcinoma .I Am Acad Dermatol 1987;16:988-990. [2] Grin CM, Kopf AW, Welkovich B, Bart RS, Levenstein MJ. Accuracy in the clinical diagnosis of malignant melanoma. Arch Dermatol 1990;126:763-766 [3] Lightstone AC, Kopf AW, Garfinkel L. Diagnostic accuracy-A new approach to its evaluation. Results in basal cell carcinomas. Arch Dermatol 1965;91:497-502. [4] Fiadeiro T, Tavares Bello RC, Feio A, Fernandes Rodrigues
findings;
IN:
histopathological
363 diagnosis
different
from
clinical
JC. Basal-cell carcinoma: diagnostic accuracy (1988-1989) Skin Cancer 1991;6:9-13. [5] Norman GR, Rosenthal D, Brooks LR, Allen SW, Muzzin LJ. The development of expertise in dermatology. Arch Dermatol 1989;125:1063-1068.
* Corresponding
author.
SSDI 0926-9959(94)00023-2