Book Review

Differential Diagnosis in Dermatopathology I

N Engl J Med 1993; 328:1050-1051April 8, 1993

Article

Differential Diagnosis in Dermatopathology I
Second edition. By A. Bernard Ackerman, Ana Maria N. Mendonca, and Ying Guo. 199 pp., illustrated. Philadelphia, Lea and Febiger, 1992. $139.50. ISBN: 0-8121-1383-7

The scope of this book is formidable; it covers not only a wide range of inflammatory dermatoses but also benign and malignant cutaneous neoplasms, for a total of 90 different diseases. As compared with other textbooks of dermatopathology, it is unique in its didactic approach. Rather than the conventional thematic narrative grouped into long chapters and interrupted by an occasional figure, this book consists of vignettes of 45 pairs of diseases and combines a clinical picture with a miniseries of photomicrographs of histologic slides at low, intermediate, and high magnification for each pair of diseases. These exceptionally high quality images are printed on one page of a two-page spread; on the opposite page is a series of brief descriptions of the two diseases, presented in a telegraphic style. These two pages are then followed by a succinct summary of relevant clinical and pathological features of the preceding pair of diseases and related disorders.

This book is based on the concept that many skin diseases have overlapping clinical and histopathological patterns, which can ultimately be separated by attention to key distinguishing attributes. The challenge for the authors is to convey exactly what those key attributes are with a few photomicrographs and some brief dialogue with the reader. This difficult task is made considerably more challenging, as the authors recognize, by the changing clinical and histologic characteristics of the disease itself. Thus, a snapshot of the fully evolved “textbook” lesion may not correspond to what physicians see at the bedside or through the microscope.

For a more complete differential diagnosis of several diseases, which took into account their evolving nature, the authors would need to narrow the scope of this book or greatly expand it. Moreover, pairs of diseases really do not represent valid clinical differential diagnoses, and the few histologic similarities they have give their inclusion in this book a gratuitous quality. Pairs of diseases that could be eliminated on this basis include: syringocystadenoma papilliferum and hidradenoma papilliferum; epidermolytic hyperkeratosis and plane wart; nevus verrucosus and acanthosis nigricans; and porokeratosis and inflammatory linear verrucous epidermal nevus.

What I am trying to suggest is that the authors should focus on the diseases suggested by their book's title -- that is, on authentic differential diagnosis. The glaring discrepancies in the clinical pictures of several of the paired diseases greatly detract from the overall presentation, and although the authors acknowledge the clinical differences in the brief narrative section that follows the visual presentation, I found this aspect of the book to be contradictory to its title. Rather than attempting to differentiate by microscopy between skin diseases that are similar histologically but clinically different, why not do something of more practical value: focus on diseases that are similar both histologically and clinically?

Another deficiency is the lack of figures or descriptions of useful supplemental procedures that can aid in the differential diagnosis. Certainly, sections routinely stained with hematoxylin and eosin can take us very close to the correct diagnosis of many diseases (with appropriate correlation with clinical features), but to fail to mention the usefulness of immunohistochemistry in the diagnostic practice of contemporary dermatopathology is most unfortunate. For example, in the differential diagnosis of reactive versus neoplastic B-cell proliferations (i.e., pseudolymphoma vs. malignant lymphoma, B-cell type), it is appropriate to distinguish a B-cell from a T-cell proliferation with appropriate monoclonal-antibody cell reagents and then to determine if a clonal population is present (which would favor a malignant over a reactive process) by staining the B cells for expression of kappa and lambda immunoglobulin light chains. Genotypic analysis is required for a complete evaluation, but immunophenotypic studies would ideally complement the light-microscopical assessment.

A related point is that many new developments have occurred in the past decade, yet this new edition of Differential Diagnosis does not incorporate them. Important newly recognized neoplasms such as microcystic adnexal carcinoma (also called sclerosing sweat-duct carcinoma) have been recognized and characterized by their clinical and immunohistochemical-staining properties. Why not devote a section to the differential diagnosis of this neoplasm and trichoepithelioma? Also, a cell type recently identified by its reactivity to factor XIIIa, called the dermal dendrocyte, is being recognized as an important constituent of dermatofibromas and other benign and malignant skin diseases. In the text, the authors refer to the “fibrocyte,” but this term is not defined in the glossary, and its relation to dermal dendrocytes or other dermal cell types is not clear.

Finally, how does the second edition differ from the first (published in 1982)? The same 90 diseases are covered in the same order, and only one clinical picture has been changed. As for the microscopical pictures, some are identical and many have been replaced, but I did not find the new ones to be much better than the already excellent figures in the previous edition. The essential histologic points are slightly altered, but these changes are relatively minor, and the new version is not substantially different from, or better than, the previous presentation. The longer narrative description for the same pairs of diseases is also similar, but not identical, to that in the previous edition. For some of the presentations, several sentences or a paragraph has been changed, but this second edition also suffers from the main flaw in the original edition -- no citation of any references in the literature. Although it is difficult to quibble about the validity of conclusions based on experiential knowledge (the authors state in the preface that they have examined more than 750,000 additional specimens in the past 15 years), I would have preferred a modern list of relevant publications.

In conclusion, this second edition is similar to the first edition in many aspects. It has many of the same positive elements (easy readability, outstanding clinical and histologic photographs and photomicrographs, and concise cataloguing of relevant histologic features), but it also has the same negative aspects (pairing disease processes that would not fall within a genuine clinical differential diagnosis, lack of results of immunohistochemical staining, and absence of citations of the scientific literature). If you own the first edition, therefore, you may wish to forgo the purchase of this second edition, which is 50 percent more expensive. If you did not buy the first edition and are willing to overlook these negative points, you could purchase the second edition and be the proud owner of a unique dermatopathology textbook that is broad in scope, well illustrated, and attractive. It will probably be of more use to the novice who is struggling to obtain an image of the clinical and light-microscopical features of fully evolved skin diseases than to the experienced dermatopathologist who tackles difficult differential diagnoses of skin diseases. Perhaps as laser-disk technology in the production of medical textbooks becomes more widely used, it will be possible to have available a more comprehensive edition that illustrates all the phases of skin diseases that present differential-diagnostic challenges, and that includes appropriate information on supplemental diagnostic procedures, results, and a bibliography.

Brian J. Nickoloff, M.D., Ph.D.
University of Michigan, Ann Arbor, MI 48109