Path. Res. Pract. 188,413-417 (1992)
An Electronic Primer in Dermatopathology H. Kolles, G. Herth 1 and K. Remberger Department of Pathology, and 1Morphological Laboratory at the Department of Anatomy, Saarland University, Homburg-Saar, FRG
SUMMARY We present an electronic primer in dermatopathology based on a full-text retrieval system which contains all the features of traditional handbooks of dermatopathology. The system including high-resolution black and white pictures with coloured overlays runs on every personal computer with VGA card and needs no additional software and hardware equipment. The representation of pictures is improved by using high-resolution VGA cards. The system is able to work like an electronic diagnostic consultant in dermatopathology.
1 Introduction Actually many knowledge-based applications are developed in the field of surgical pathology3,9, 10, 12. We present an electronic primer in dermatopathology which consists of a database architecture in connection with a powerful full-text retrieval system? and a graphic display system. The system can be used both as a diagnostic encyclopedia workstation 6 and as an electronic diagnostic consultant. The main problem in using such a system is to find all theoretically possible diagnoses in dependence of the specified morphological criteria. Consequently a standardized nomenclature eliminating all occuring synonyma has to be implemented. The use of the recent optical scanner technology in connection with OCR programs (Optical Characater Recognition) allows to scan in a great number of morphological criteria. For prototype development we have used two standard handbooks in dermatopathologyl,4. The system does not require any additional software and runs on all DOS-based personal computers or compatibles. The prototype is intended for a single user station but some simple modifications in the program allow to use the system in a local area network (LAN). 2 Material and Methods 2.1 Information Proc~,ssing
Our electronic primer shell is written in Clipper8 , a dBASE (TM) dialect for relational database applications. © 1992 by Gustav Fischer Verlag, Sumgart
The database architecture is used to store the diagnoses with their corresponding morphological criteria. For information processing two different possibilities are available which can be combined during a consultation: The hypertext mode allows a quick retrieval of all diagnoses in dependence of the 31 standardized morphological findings presently available. For these standardized criteria all synonyms are also known by the system (Tab. 1). Several morphological diagnostic criteria can be chosen to restrict the pool of possible diagnoses. The full-text mode is used to extract or eliminate all the diagnoses which contain a specified search string in the list of the morphological criteria. It works more slowly than the hypertext mode but it is more flexible because the search string can be specified arbitrarily (e.g. truncated words or strings composed of several words). 2.2 Image Processing Taking and processing the pictures has been carried out on a special workstation provided with an image analysing system. The image reproduction as a part of the electronic primer, however, can be done on every PC with suitable equipment. Pictures were taken from a collection of selected slide preparations of dermatopathological diseases. The dermatopathological specimens were stained by standard methods (H. E., Giemsa, etc.).' The image processing was done by means of the image analysing system lBAS (Kontron Inc., Munich FRG), which consists of an image computer, a controlling computer based upon a 386-AT, as well as diverse peripheral components for input and output facilities. The optical information of the individual slides is converted to a binary image with 256 grey 0344-0338/92/0188-0413$3.50/0
414 . H. Kolies, G. Herth and K. Remberger Table 1. The 31 standardized morphological criteria used by the electronic primer. Only the upper characters are significant for the full-text retrieval Criterion
Synonyma
ABSCESS ATROPHy
pustule, accumulation of neutrophils thin epidermis, hypogranulosis, flattening or loss of rete ridges mitoses, pleomorphic, hyperchromatic bulla, vesicle, cleft, space, acantholysis granules, globules, particles elastosis
ATYPia BLISTER BODY DEGENERATion DYSKERATosis EDEMA EOSINOPHILS ERYTHROCYTE hemorrhage FIBRIN sclerosis, collagen changes, scar, keloid FIBRO GIANT CELLS GRANULOMA GRENZ ZONE HYPERKERATosis HYPERPLASia papillomatosis, hypergranulosis, acanthosis, elongated rete ridges INFILTRATE MAST CELLS MELANOPHAGES nuclear dust, pyknosis NECROsis ORGANISM PALISADe PARAKERATosis melanin pigment incontinence PI GMENTation PLASMA CELLS squama, squamotization SCALE intraepidermal edema SPONGIOsis erosion, excoriation ULCERation VACUOLation endothel, vascular VESSEL
values and a resolution of 640 X 512 pixels (predefined by the system). Beside the hardware specific of image analysis the IBAS consists of software that allows to work on complex morphometric operations. The software was used to write computer programs being able to find out structural and neighbourhood-related information depending on given morphological criteria. IBAS stores the information of the processed pictures as a binary file. For the later representation these files are converted into the popular PCX format 2 • Thereby the resolution is reduced to 640 X 480 pixel and a reduction of the amount of data is done by the PCX -own data compression. Depending on the contents of the pictures the final size of the compressed files is about 150 to 250 KB. Since the introduction of VGA cards hardware is available allowing representations in 256 different colours. Standard VGA systems (like the original IBM device), however, show these only at a resolution of 320: 200 pixel. For our purposes we use so-called Super-VGAs which in connection with a multi-sync monitor allow a resolution of 640 X 480 pixel in 256 colours. Generally these types of graphic adaptors have 512 kB video memory on their own. Unfortunately the individual products differ essentially in programming the higher resolution modes. The graphic representation of the pictures is therefore performed by an independent program adapted to the hardware used. The
electronic primer calls the external program with corresponding parameters for the representation of the stored images.
3 Results 3.1 Information Processing
The results concerning the information processing are partly illustrated by means of the corresponding screen masks (Fig. la-c). The user can choose the menus by means of movable light bars. The principle of a "consultation" is to enter morphological diagnostic criteria which are processed by the system to establish a list of probable diagnoses. It is possible to specify "and"-, "or"- and "not" -relations between the criteria. To use the system as
All ELECTRONIC PRIMER IN DERMATOPATIIOl.OGY
1. 2. 3. 4. 5. 6.
a
CONSULTATION - HYPERTEXT MODE CONSULTATION - FULL TEXT MODE EDIT CRITERIA EDIT KNOWLEDGE BASE SAVE KNOWLEDGE BASE SEARCH & REPLACE IN KNOWLEDGE BASE 7. STRING COUNTING IN KNOWLEDGE BASE 8. LOAD/APPEND KNOWLEDGE BASE 9. EXIT
HYPERTEXT IDlE Specify the criteria.
(Hit twice to cancel)
· FIBRO · GIANT CELL_s . GRANULOMA ·GRENZ ZONE *HYPERKERAT osis *HYPERPLAs3a · INFILTRATE ·MAST CELL_s ·MELANOPHAGE_s
b FULL TEXT IDlE HIT SELECTION Enter search string (Empty string to cancel; Blank is
):
hyperkerat Records with hits:
Conservation
[OJ
Elimination
[1]:
0
Record N° 470 is processed Number of hits: 71 Number of records to process: 470
c
Number of records after search: 71 Any key to continue ...
Fig. 1. Different screen masks of the electronic primer. a: The main menu of the electronic primer. - b: The menu "hypertext mode" serving to perform a high-speed full-text search. - c: The menu "full-text mode" serving to perform a fulltext search.
An Electronic Primer in Dermatopathology . 415
an electronic consultant there are two possible modes, the hypertext mode (Fig. 1 b) and the full-text mode (Fig. 1 c), producing a database containing all diagnoses with the specified morphological criteria. If it is not desired that the knowledge base should be restricted to the diagnoses containing a certain search criterion the menu "string counting in knowledge base" is available. This mode performs a simple counting of diagnoses in the underlying database in dependence of the specified morphological criterion. It is basically intended to get an overview of the specifity of the selected diagnostic criterion. Finally the
menus "search and replace " and the database editor can be used to update the databases containing diagnoses and criteria. Furthermore the database editor selects and shows t~e reference pictures corresponding to the actual diagnoSIS.
3.2 Image Processing The example of the diagnosis "lupus erythematosus" demonstrates the transformation of dermatopathological criteria into morphological parameters. This disease is
.-
.•
•
Fig. 2. Reproductions of digital tmages (PeX-format) representing some characteristical morphological criteria related to lupus erythematosus: Epidermal atrophy and Iymphohistiocytic infiltrate in the reticular dermis (a) extending into appendageal epithelium with vacuolation of basal cells (b) as well as follicular plugs (c). The labels, borderlines, rectangles which appear in different colors on the computer screen are shown here only in black and white.
..,..
-
416 . H. KoBes, G. Herth and K. Remberger
Fig.2c
characterized inter alia by an atrophic epidermis as well as by patchy infiltrates of histiocytes and lymphocytes in the dermis (Fig.2a) extending into appendageal epithelium with vacuolation of Basal cells (Fig. 2b). Futher characteristics of lupus erythematosus are follicular keratin plugs (Fig.2c). The epidermis, the cellular infiltrates and the follicular plugs can be distinguished from their environment morphologically by their grey value. The level of discrimination depends on many factors (e.g. the methods of staining) and is therefore set interactively. The r~sults of the image processing and analysis are marked by coloured borderlines.
4 Discussion Our electronic primer in dermatopathology has a function similar to a book on dermatopathology. It is, however, more flexible than a traditionally written book. By means of the integrated full-text retrieval system a powerful cross referencing is possible. By combining conservation and elimination of certain diagnoses in dependence of specified morphological criteria it is possible to select quickly a list of significant differential diagnoses. So our system can be considered in some respects as a diagnostic consultant or as a simple expert system. Compared to other diagnostic encyclopaedia workstations 6 our system needs no additional hardware to display high-resolution images. The pictures of our system are available in digital form and can therefore be transferred by any data media. Using this approach it is theoretically possible to connect different personal computer stations in a local area netvvork (LAN) or in a wide area network (WAN). Thus.it will be possible
to build central organ-specific reference databases in the different fields of pathology with a great number of reference pictures accessible by data transmission. In spite of the possibilities offered by the representation on VGA we have decided to show the pictures in grey shades with coloured overlays for the following reasons: - For VGA representation purposes the conversion of an image, taken with a colour camera and digitized, requires a data reduction from usually 24 bit (8 bit for the red, green and blue part resp.) to 8 bit. This does not produce in all cases satisfactory results and is connected to a great effort of the programmer ll . - The amount of data needed by a grey value picture is considerably smaller than that needed by a colour picture but the information density is comparable. - The eye is reacting much more sensitive to sliding colours inevitably appearing with such data reductions than to grey value differences 5 . - The additional coloured overlayed information is helpful in surveying and remembering morphological information in grey shade images. It is just the integration of images into the diagnostic system that makes the program a complete electronic primer. This symbiosis makes sense because the highest information flow is reached by visual information exchange. The morphological criteria used at image analysis and represented as additional information on the screen correspond exactly to those used in the consulting modes. . The pictures provided in PCX-format can be used independently of our program. Therefore we are planning to use the same pictures in a learning and teaching system for clinical education of students or to make them available to other interested departments.
An Electronic Primer in Dermatopathology . 417 References 1 Ackerman AB (1978) Histologic diagnosis of inflammatory skin diseases. A method by pattern analysis. Lea & Febiger, Philadelphia 2 Born G (1990) Referenzhandbuch Dateiformate. AddisonWesley, Miinchen 3 Haux R (1988/89) Expertensysteme in der Medizin, eine einfiihrende Dbersicht. Software Kurier. (Part 1) 1: 65-77 (Part 2) 2: 1-11 4 Hood AF, Kwan TH, Burnes DC, MIHM MC (1984) Primer of Dermatopathology. Little, Brown & Company. BostonlToronto 5 Inoue S (1989) Video Microscopy. Plenum Press. New York 6 Jansen W, BaakJPA, Smeulders AWM, Van Ginneken AM (1989) A computer-based handbook and atlas of pathology. Path Res Pract 185: 652-656
7 Kolles H, Remberger K (1991) How to build a computerassisted diagnosis finding system. An example in dermatopathology. Arch Pathol Lab Med 115: 1011-1015 8 Nantucket Corp. (1987) The Clipper Compiler, Nantucket Corp. Los Angeles and LeverkusenIFRG 9 Nathwani BN, Heckerman DE, Horvitz EJ, Lincoln TL (1990) Integrated expert systems and videodisc in surgical pathology. An overview. Hum Pathol 21: 11-27 10 Oberholzer M, Feichter G, Dalquen P, Ettlin R, Christe H, Buser M (1989) A simple "Expert System" for morphometric evaluation of cells in pleural effusions. Path Res Pract 185: 647-651 11 Schaale M (1989) Farbenlotto. Wiedergabe von Echtfarbbildern mit VGA-Karte. C'T 12: 166-177 12 Schill K (1990) Medizinische Expertensysteme. Methoden und Techniken. Oldenbourg-Miinchen-Wien
Received September 27, 1991 . Accepted October 28, 1991
Key words: Diagnostic encyclopedia workstation - Electronic primer - Dermatopathology - EDP Dr. med. Harry Kolles, Pathologisches Institut der Univcrsitatskliniken, Universitat des Saarlandes, D-W 6650 Homburg/Saar, FRG
An Electronic Primer in Dermatopathology H. Kolles, G. Herth 1 and K. Remberger Department of Pathology, and 1Morphological Laboratory at the Department of Anatomy, Saarland University, Homburg-Saar, FRG
SUMMARY We present an electronic primer in dermatopathology based on a full-text retrieval system which contains all the features of traditional handbooks of dermatopathology. The system including high-resolution black and white pictures with coloured overlays runs on every personal computer with VGA card and needs no additional software and hardware equipment. The representation of pictures is improved by using high-resolution VGA cards. The system is able to work like an electronic diagnostic consultant in dermatopathology.
1 Introduction Actually many knowledge-based applications are developed in the field of surgical pathology3,9, 10, 12. We present an electronic primer in dermatopathology which consists of a database architecture in connection with a powerful full-text retrieval system? and a graphic display system. The system can be used both as a diagnostic encyclopedia workstation 6 and as an electronic diagnostic consultant. The main problem in using such a system is to find all theoretically possible diagnoses in dependence of the specified morphological criteria. Consequently a standardized nomenclature eliminating all occuring synonyma has to be implemented. The use of the recent optical scanner technology in connection with OCR programs (Optical Characater Recognition) allows to scan in a great number of morphological criteria. For prototype development we have used two standard handbooks in dermatopathologyl,4. The system does not require any additional software and runs on all DOS-based personal computers or compatibles. The prototype is intended for a single user station but some simple modifications in the program allow to use the system in a local area network (LAN). 2 Material and Methods 2.1 Information Proc~,ssing
Our electronic primer shell is written in Clipper8 , a dBASE (TM) dialect for relational database applications. © 1992 by Gustav Fischer Verlag, Sumgart
The database architecture is used to store the diagnoses with their corresponding morphological criteria. For information processing two different possibilities are available which can be combined during a consultation: The hypertext mode allows a quick retrieval of all diagnoses in dependence of the 31 standardized morphological findings presently available. For these standardized criteria all synonyms are also known by the system (Tab. 1). Several morphological diagnostic criteria can be chosen to restrict the pool of possible diagnoses. The full-text mode is used to extract or eliminate all the diagnoses which contain a specified search string in the list of the morphological criteria. It works more slowly than the hypertext mode but it is more flexible because the search string can be specified arbitrarily (e.g. truncated words or strings composed of several words). 2.2 Image Processing Taking and processing the pictures has been carried out on a special workstation provided with an image analysing system. The image reproduction as a part of the electronic primer, however, can be done on every PC with suitable equipment. Pictures were taken from a collection of selected slide preparations of dermatopathological diseases. The dermatopathological specimens were stained by standard methods (H. E., Giemsa, etc.).' The image processing was done by means of the image analysing system lBAS (Kontron Inc., Munich FRG), which consists of an image computer, a controlling computer based upon a 386-AT, as well as diverse peripheral components for input and output facilities. The optical information of the individual slides is converted to a binary image with 256 grey 0344-0338/92/0188-0413$3.50/0
414 . H. Kolies, G. Herth and K. Remberger Table 1. The 31 standardized morphological criteria used by the electronic primer. Only the upper characters are significant for the full-text retrieval Criterion
Synonyma
ABSCESS ATROPHy
pustule, accumulation of neutrophils thin epidermis, hypogranulosis, flattening or loss of rete ridges mitoses, pleomorphic, hyperchromatic bulla, vesicle, cleft, space, acantholysis granules, globules, particles elastosis
ATYPia BLISTER BODY DEGENERATion DYSKERATosis EDEMA EOSINOPHILS ERYTHROCYTE hemorrhage FIBRIN sclerosis, collagen changes, scar, keloid FIBRO GIANT CELLS GRANULOMA GRENZ ZONE HYPERKERATosis HYPERPLASia papillomatosis, hypergranulosis, acanthosis, elongated rete ridges INFILTRATE MAST CELLS MELANOPHAGES nuclear dust, pyknosis NECROsis ORGANISM PALISADe PARAKERATosis melanin pigment incontinence PI GMENTation PLASMA CELLS squama, squamotization SCALE intraepidermal edema SPONGIOsis erosion, excoriation ULCERation VACUOLation endothel, vascular VESSEL
values and a resolution of 640 X 512 pixels (predefined by the system). Beside the hardware specific of image analysis the IBAS consists of software that allows to work on complex morphometric operations. The software was used to write computer programs being able to find out structural and neighbourhood-related information depending on given morphological criteria. IBAS stores the information of the processed pictures as a binary file. For the later representation these files are converted into the popular PCX format 2 • Thereby the resolution is reduced to 640 X 480 pixel and a reduction of the amount of data is done by the PCX -own data compression. Depending on the contents of the pictures the final size of the compressed files is about 150 to 250 KB. Since the introduction of VGA cards hardware is available allowing representations in 256 different colours. Standard VGA systems (like the original IBM device), however, show these only at a resolution of 320: 200 pixel. For our purposes we use so-called Super-VGAs which in connection with a multi-sync monitor allow a resolution of 640 X 480 pixel in 256 colours. Generally these types of graphic adaptors have 512 kB video memory on their own. Unfortunately the individual products differ essentially in programming the higher resolution modes. The graphic representation of the pictures is therefore performed by an independent program adapted to the hardware used. The
electronic primer calls the external program with corresponding parameters for the representation of the stored images.
3 Results 3.1 Information Processing
The results concerning the information processing are partly illustrated by means of the corresponding screen masks (Fig. la-c). The user can choose the menus by means of movable light bars. The principle of a "consultation" is to enter morphological diagnostic criteria which are processed by the system to establish a list of probable diagnoses. It is possible to specify "and"-, "or"- and "not" -relations between the criteria. To use the system as
All ELECTRONIC PRIMER IN DERMATOPATIIOl.OGY
1. 2. 3. 4. 5. 6.
a
CONSULTATION - HYPERTEXT MODE CONSULTATION - FULL TEXT MODE EDIT CRITERIA EDIT KNOWLEDGE BASE SAVE KNOWLEDGE BASE SEARCH & REPLACE IN KNOWLEDGE BASE 7. STRING COUNTING IN KNOWLEDGE BASE 8. LOAD/APPEND KNOWLEDGE BASE 9. EXIT
HYPERTEXT IDlE Specify the criteria.
(Hit twice to cancel)
· FIBRO · GIANT CELL_s . GRANULOMA ·GRENZ ZONE *HYPERKERAT osis *HYPERPLAs3a · INFILTRATE ·MAST CELL_s ·MELANOPHAGE_s
b FULL TEXT IDlE HIT SELECTION Enter search string (Empty string to cancel; Blank is
):
hyperkerat Records with hits:
Conservation
[OJ
Elimination
[1]:
0
Record N° 470 is processed Number of hits: 71 Number of records to process: 470
c
Number of records after search: 71 Any key to continue ...
Fig. 1. Different screen masks of the electronic primer. a: The main menu of the electronic primer. - b: The menu "hypertext mode" serving to perform a high-speed full-text search. - c: The menu "full-text mode" serving to perform a fulltext search.
An Electronic Primer in Dermatopathology . 415
an electronic consultant there are two possible modes, the hypertext mode (Fig. 1 b) and the full-text mode (Fig. 1 c), producing a database containing all diagnoses with the specified morphological criteria. If it is not desired that the knowledge base should be restricted to the diagnoses containing a certain search criterion the menu "string counting in knowledge base" is available. This mode performs a simple counting of diagnoses in the underlying database in dependence of the specified morphological criterion. It is basically intended to get an overview of the specifity of the selected diagnostic criterion. Finally the
menus "search and replace " and the database editor can be used to update the databases containing diagnoses and criteria. Furthermore the database editor selects and shows t~e reference pictures corresponding to the actual diagnoSIS.
3.2 Image Processing The example of the diagnosis "lupus erythematosus" demonstrates the transformation of dermatopathological criteria into morphological parameters. This disease is
.-
.•
•
Fig. 2. Reproductions of digital tmages (PeX-format) representing some characteristical morphological criteria related to lupus erythematosus: Epidermal atrophy and Iymphohistiocytic infiltrate in the reticular dermis (a) extending into appendageal epithelium with vacuolation of basal cells (b) as well as follicular plugs (c). The labels, borderlines, rectangles which appear in different colors on the computer screen are shown here only in black and white.
..,..
-
416 . H. KoBes, G. Herth and K. Remberger
Fig.2c
characterized inter alia by an atrophic epidermis as well as by patchy infiltrates of histiocytes and lymphocytes in the dermis (Fig.2a) extending into appendageal epithelium with vacuolation of Basal cells (Fig. 2b). Futher characteristics of lupus erythematosus are follicular keratin plugs (Fig.2c). The epidermis, the cellular infiltrates and the follicular plugs can be distinguished from their environment morphologically by their grey value. The level of discrimination depends on many factors (e.g. the methods of staining) and is therefore set interactively. The r~sults of the image processing and analysis are marked by coloured borderlines.
4 Discussion Our electronic primer in dermatopathology has a function similar to a book on dermatopathology. It is, however, more flexible than a traditionally written book. By means of the integrated full-text retrieval system a powerful cross referencing is possible. By combining conservation and elimination of certain diagnoses in dependence of specified morphological criteria it is possible to select quickly a list of significant differential diagnoses. So our system can be considered in some respects as a diagnostic consultant or as a simple expert system. Compared to other diagnostic encyclopaedia workstations 6 our system needs no additional hardware to display high-resolution images. The pictures of our system are available in digital form and can therefore be transferred by any data media. Using this approach it is theoretically possible to connect different personal computer stations in a local area netvvork (LAN) or in a wide area network (WAN). Thus.it will be possible
to build central organ-specific reference databases in the different fields of pathology with a great number of reference pictures accessible by data transmission. In spite of the possibilities offered by the representation on VGA we have decided to show the pictures in grey shades with coloured overlays for the following reasons: - For VGA representation purposes the conversion of an image, taken with a colour camera and digitized, requires a data reduction from usually 24 bit (8 bit for the red, green and blue part resp.) to 8 bit. This does not produce in all cases satisfactory results and is connected to a great effort of the programmer ll . - The amount of data needed by a grey value picture is considerably smaller than that needed by a colour picture but the information density is comparable. - The eye is reacting much more sensitive to sliding colours inevitably appearing with such data reductions than to grey value differences 5 . - The additional coloured overlayed information is helpful in surveying and remembering morphological information in grey shade images. It is just the integration of images into the diagnostic system that makes the program a complete electronic primer. This symbiosis makes sense because the highest information flow is reached by visual information exchange. The morphological criteria used at image analysis and represented as additional information on the screen correspond exactly to those used in the consulting modes. . The pictures provided in PCX-format can be used independently of our program. Therefore we are planning to use the same pictures in a learning and teaching system for clinical education of students or to make them available to other interested departments.
An Electronic Primer in Dermatopathology . 417 References 1 Ackerman AB (1978) Histologic diagnosis of inflammatory skin diseases. A method by pattern analysis. Lea & Febiger, Philadelphia 2 Born G (1990) Referenzhandbuch Dateiformate. AddisonWesley, Miinchen 3 Haux R (1988/89) Expertensysteme in der Medizin, eine einfiihrende Dbersicht. Software Kurier. (Part 1) 1: 65-77 (Part 2) 2: 1-11 4 Hood AF, Kwan TH, Burnes DC, MIHM MC (1984) Primer of Dermatopathology. Little, Brown & Company. BostonlToronto 5 Inoue S (1989) Video Microscopy. Plenum Press. New York 6 Jansen W, BaakJPA, Smeulders AWM, Van Ginneken AM (1989) A computer-based handbook and atlas of pathology. Path Res Pract 185: 652-656
7 Kolles H, Remberger K (1991) How to build a computerassisted diagnosis finding system. An example in dermatopathology. Arch Pathol Lab Med 115: 1011-1015 8 Nantucket Corp. (1987) The Clipper Compiler, Nantucket Corp. Los Angeles and LeverkusenIFRG 9 Nathwani BN, Heckerman DE, Horvitz EJ, Lincoln TL (1990) Integrated expert systems and videodisc in surgical pathology. An overview. Hum Pathol 21: 11-27 10 Oberholzer M, Feichter G, Dalquen P, Ettlin R, Christe H, Buser M (1989) A simple "Expert System" for morphometric evaluation of cells in pleural effusions. Path Res Pract 185: 647-651 11 Schaale M (1989) Farbenlotto. Wiedergabe von Echtfarbbildern mit VGA-Karte. C'T 12: 166-177 12 Schill K (1990) Medizinische Expertensysteme. Methoden und Techniken. Oldenbourg-Miinchen-Wien
Received September 27, 1991 . Accepted October 28, 1991
Key words: Diagnostic encyclopedia workstation - Electronic primer - Dermatopathology - EDP Dr. med. Harry Kolles, Pathologisches Institut der Univcrsitatskliniken, Universitat des Saarlandes, D-W 6650 Homburg/Saar, FRG
