Compressed JPEG images of case 1 (trichofolliculoma) at different
original magnifications: A, ×4; B, ×10; and C, ×40.
Piccolo D, Soyer HP, Burgdorf W, Talamini R, Peris K, Bugatti L, Canzonieri V, Cerroni L, Chimenti S, De Rosa G, Filosa G, Hoffmann R, Julis I, Kutzner H, Manente L, Misciali C, Schaeppi H, Tanaka M, Tyler W, Zelger B, Kerl H. Concordance Between Telepathologic Diagnosis and Conventional Histopathologic DiagnosisA Multiobserver Store-and-Forward Study on 20 Skin Specimens. Arch Dermatol. 2002;138(1):53-58. doi:10.1001/archderm.138.1.53
To study the validity and feasibility of transferring images of cutaneous
biopsy specimens via e-mail to remote physicians active in dermatopathology
Twenty skin specimens previously diagnosed at the Department of Dermatology,
University of Graz, Austria, were subsequently sent for teleconsultation using
the store-and-forward method. For each case, 3 or 4 images at different magnifications
were sent by e-mail to 16 colleagues (11 dermatopathologists and 5 pathologists)
in 15 centers in 6 different countries. Six weeks later each observer received
the hematoxylin-eosin–stained specimens to render a conventional diagnosis.
Dermatopathology and pathology units within institutional and private
Twenty small skin biopsy specimens of cutaneous diseases were selected
randomly from a study set of 80.
Main Outcome Measure
Concordance between telepathologic diagnoses and conventional histopathologic
diagnoses of 20 skin specimens.
On average, 78% of the telediagnoses were correct (range, 60%-95%),
whereas 85% of the conventional diagnoses were correct (range, 60%-95%). A
perfect diagnostic concordance was obtained in 7 (35%) of 20 cases, and a
significant difference was identified in only 1 case.
Results suggest that telepathology performed by physicians active in
dermatopathology may serve as a reliable technique for the diagnosis of cutaneous
diseases when experts in dermatopathology are not available locally. Furthermore,
teledermatopathology is attractive because it provides an opportunity to obtain
timely consultation on difficult cases.
IN RECENT years, continuous progress in computer technology has led
to the introduction of a revolutionary diagnostic tool known as telemedicine.1- 3Telepathology is defined as the practice of pathology at
a distance, by visualizing an image on a monitor rather than viewing a specimen
directly through a microscope.4- 14
Using relatively simple equipment, dermatologists can rapidly transmit
microscopic still images photographed at one site to remote centers to obtain
a diagnostic consultation. Today's technologies allow a transfer of histopathologic
images in both dynamic (real-time) and static (store-and-forward) systems.
The first method provides remote consultation via a robotic microscope, which
can be controlled by the consulting pathologist. The equipment used for robotic
systems is relatively expensive and requires high data transmission rates
to achieve real-time image transfer. Using the store-and-forward method, each
image is captured and transmitted as a single file. The fields to be examined
are selected by the referring pathologist and then transmitted. This system
is much less expensive and does not require high-speed data transmission capability.
A limited number of studies have addressed the validity of both these systems,
and results suggest that static-image telepathology may be less accurate.15- 20
A number of studies have demonstrated that teledermatology represents
a useful diagnostic tool, especially in communities where dermatologic services
are not available.21- 29 Our group has published 2 studies demonstrating the reliability and reproducibility
of store-and-forward teledermoscopy for the diagnosis of pigmented skin lesions.30,31 In contrast, only a few teledermatopathology
studies have been done.10,19
We report the results of a multicenter teledermatopathologic study on
20 cutaneous specimens. A total of 67 JPEG (joint photographic experts group)
compressed representative static images were sent by e-mail from Graz, Austria,
to 16 telepathologists around the world (Austria, Czech Republic, Germany,
Italy, Japan, and the United States). Each participant rendered a telepathologic
diagnosis for each case. After 6 weeks, all participants received representative
hematoxylin-eosin–stained specimens of each case and rendered another
diagnosis. Comparing these diagnoses allowed us to evaluate the concordance
between the telepathologic and conventional diagnoses.
Our study included 20 histopathologic biopsy specimens of cutaneous
diseases selected randomly from a study set of 80. We concentrated on small
tissue specimens to avoid sampling error. Essential clinical information,
the number of images sent for each case, and the final diagnoses are given
in Table 1. The clinical information
was included on the actual histopathology laboratory submission form. For
example, for case 1, a trichofolliculoma, the clinical information read "59-year-old
female with a lesion on the forehead clinically diagnosed as sebaceous hyperplasia."
In most cases, the information was scant. All original histopathologic specimens
were examined with a conventional microscope (BX50; Olympus, Tokyo, Japan)
at the Department of Dermatology in Graz by 2 expert dermatopathologists (H.
Kerl and H.P.S.). One of them selected the fields to be photographed from
the original specimen and chose the magnification level. The final diagnosis
for these cases was made by both of the expert dermatopathologists in Graz
by assessing clinical features and histopathologic findings.
Images were captured with a digital Kodak DCS 460 camera (Eastman Kodak
Co, Rochester, NY), which uses a Nikon N90 body (Tokyo, Japan) mounted on
an ordinary Olympus BX50 microscope. Each image was obtained with the digital
camera in PICT format file (Macintosh native graphics format). For each case,
images at 3 or 4 different magnifications were acquired (Figure 1). The original size of these images was 17 megabytes, 2036
× 3060 pixels (71.83 × 107.96 cm; 72 pixels per inch [ppi]), in
RGB color mode (36 bit). Successively, all images were subsampled to a size
of 511 × 768 pixels (18.02 × 27.08 cm; 72 ppi) in RGB color mode
(24 bit) and compressed by using JPEG compression at a fixed quality setting.
The software used for subsampling and compression was Adobe Photoshop 4.0
(Adobe, San Jose, Calif); the JPEG quality setting was set at 6 (this value
is proportional to compression ratio). Finally, compressed images had a mean
size of 53 kilobytes (kb) (range, 48-67 kb). This compression was required
to allow a faster e-mail transmission. All images were sent to the remote
centers via e-mail (Eudora Light, San Diego, Calif) together with basic patient
data (age, sex, site and duration of the lesion, and clinical diagnosis).
The χ2 test and Fisher exact test were used for quantitative
parameters. Results were considered statistically significant at P≤.05 (2-sided).32
The clinical data, number of images, final diagnosis by both the expert
dermatopathologists in Graz, and the number of correct telediagnoses and correct
conventional diagnoses for the 20 cases are given in Table 1. A diagnostic concordance between the telediagnoses and
conventional diagnoses of the 16 pathologists was obtained in 7 (35%) of 20
cases (cases 1, 4, 8, 11, 16, 18, and 19). A significant difference between
telediagnoses and conventional diagnoses was identified in only 1 case (case
20). Telediagnoses were superior to conventional diagnoses in 4 (20%) of 20
cases (cases 2, 10, 13, and 14), whereas in 9 (45%) of 20 cases (cases 3,
5, 6, 7, 9, 12, 15, 17, and 20), telediagnoses were inferior to conventional
The performance of each participant is summarized in Table 2. Detailed results on telepathologic diagnosis, conventional
histopathologic diagnosis, and concordance between these 2 methods for each
of the 20 skin specimens is given for each independent observer. If the same
incorrect diagnosis was made on both telediagnosis and conventional diagnosis,
this is interpreted as "agreement." For example, observer 1 made 16 correct
telediagnoses and 19 correct conventional diagnoses, but only 15 diagnoses
were concordant. Thus he or she changed all 4 incorrect telediagnoses, but
also changed 1 correct telediagnosis. On average, 78% of the telediagnoses
were correct, with a range from 60% to 95%, whereas conventional diagnoses
were correct 85% of the time (range, 60%-95%). Differences of 10% or less
from perfect agreement were found among 11 (69%) of 16 observers (observers
2, 3, 4, 7, 8, 10, 11, 13, 14, 15, and 16). Differences greater than 10% to
15% occurred among 4 observers (25%; observers 1, 6, 9, and 12), whereas for
only 1 observer (6%; observer 5) was the difference from perfect agreement
more than 15%. No statistical differences were found comparing the percentage
of perfect agreement between telediagnoses and conventional diagnoses for
each observer (P>.05).
Table 3 summarizes detailed data on telepathologic diagnoses and conventional histopathologic diagnoses of all 20 skin specimens. It allows one to identify which diagnoses were proposed in addition to the final diagnosis.
In this study, we evaluated the influence of image selection on diagnostic performance to verify concordance between conventional diagnosis and telediagnosis. The results obtained showed that telepathology accuracy was slightly lower than glass slide accuracy (78% and 85%, respectively). Nevertheless, among 15 (94%) of 16 observers, no significant differences in accuracy were found between telepathology and conventional pathology, suggesting the usefulness of teledermatopathology.
Telepathology involves the use of the new telematic technologies to transmit images for the purposes of diagnosis, consultation, and education. In the past years, many articles on telepathology have been published.4- 20 Moreover, many Web sites teaching with telepathology can be found easily with the common search engines. The major problem using e-mail is that the security and confidentiality of the patient data may be compromised by hackers.11
The main problems with static telepathology are image selection and image quality. Image selection is more of a problem for the store-and-forward system. It is important to emphasize that the referring pathologist must select images that adequately present the case without attempting to influence the remote pathologists. The main risk lies in a personal and incomplete photographic characterization of the case on the basis of a diagnostic hypothesis, inadvertently leading the remote pathologist toward a diagnostic misinterpretation. The referring pathologist and the consultant should understand the risks involved in embracing and using these technologies. The store-and-forward method should be considered in small dermatopathology biopsy specimens where the sampling bias is not a major problem. In a large solid tumor, for example, image selection by the local pathologist could represent a greater obstacle.
Problems such as these might be avoided by using a remote-control telepathology system, where the consultant pathologist controls the microscope, directly choosing the areas of viewing and the magnification. One disadvantage, however, of using the real-time systems is that they are more technologically complex and expensive. Furthermore, the consultant pathologist must be online together with the referring pathologist.
The quality of the histopathologic images depends on the equipment used and the capacity of the telecommunications link. For our study, all 67 histopathologic images were compressed using JPEG compression. As demonstrated by Okumura et al33 in 1997 and by Kittler et al34 in 1998, with this type of compression the lost information is most likely to be imperceptible to the individual doing the remote assessment. The compression of the images was necessary to allow a faster e-mail transmission; JPEG is an accepted standard image type for the multipurpose Internet mail extension (MIME). This technology is an extension to the e-mail message format facilitating the delivery of multimedia messages such as images, sounds, and movies.
Making telepathologic diagnosis on a high-resolution monitor is qualitatively different than directly viewing images through a conventional light microscope. Becker et al35 demonstrated the importance of experience in using a telepathology system both for accurate reading of video images and for effective communication between sending and receiving pathologists. The telepathologic diagnostic accuracy of many of these systems is untested. Our study suggests that for small biopsy specimens, the sampling procedure is not really problematic and that the store-and-forward method works well.
In 5 cases (cases 4, 8, 11, 13, and 16), the telepathologic diagnosis was identical to the final diagnosis established by clinicopathologic correlation, whereas the conventional histopathologic diagnosis was the same as the final diagnosis in 6 cases (cases 4, 5, 8, 11, 12, and 16). In 2 cases (cases 1 and 2), there was only a slight difference between telediagnoses and conventional diagnoses compared with the final diagnosis. In case 1, three of 16 pathologists preferred the diagnosis of trichoepithelioma instead of trichofolliculoma not only when viewing transmitted images but also by conventional microscopy. In case 2, two remote pathologists and 4 pathologists performing conventional diagnosis made the diagnosis of xanthoma instead of xanthelasma. In cases 6, 7, and 9, only the combination of both clinical and histopathologic findings permitted one to obtain the final diagnoses (pityriasis lichenoides for the first case, Grover disease for the second, and Hailey-Hailey disease for the third). On the basis of only the histopathologic features, many participants diagnosed other bullous diseases such as pemphigus, Darier disease, herpesvirus infection, and acantholytic dermatitis for cases 7 and 9 (Table 3). This result underscores the importance of meticulous clinicopathologic correlation for the diagnosis of certain inflammatory skin diseases. Such a clinicopathologic correlation could be achieved by evaluating a relevant clinical image, something that could be integrated in a telepathology protocol.
This study is based on only 20 skin specimens. We have confirmed that the store-and-forward method is a useful tool within the field of dermatopathology at least when dealing with small biopsy specimens where sampling bias is not a major obstacle. Particularly in inflammatory skin diseases, a meticulous clinicopathologic correlation is still crucial for achieving competent diagnosis.
Accepted for publication May 1, 2001.
Corresponding author: H. Peter Soyer, MD, Department of Dermatology, University of Graz, Auenbruggerplatz 8, A-8036 Graz, Austria