Atlas and synopsis of Lever's histopathology of the skin, Third Edition. D. E. Elder, R. Elenitsas, A. I. Rubin, M. Iofredda, J. Miller, O. F. Miller III. Wolters Kluwer/Lippincott Williams & Wilkins, Philadelphia, PA, 2013, 531 pages.

The perfect format for an introductory dermatopathology textbook has yet to be derived. The relationships between clinical and microscopic images form somewhat of a vicious circle – one is never sure where to advise a beginner to step in. In addition, individuals are likely to enter dermatopathology from two quite different backgrounds – clinical dermatology and anatomic pathology. One group knows the clinical features but is unaccustomed to recognizing both microscopic patterns and cytological details; the other group instantly spots granulomatous inflammation or atypical lymphocytes but has no idea what granulomatous slack skin could be.

Clearly the least useful approach for beginners is a dermatopathology primer following the traditional groupings of a clinical dermatology textbook such as infectious diseases, papulosquamous disorders, genodermatoses, connective tissue diseases and the many subcategories of neoplasms. Somewhat surprisingly, this is the format employed by almost all the widely used dermatopathology textbooks. The novice is expected to somehow magically know the problem is autoimmune only by seeing a thinned epidermis and damaged epidermis. The first person to attack the problem of how to microscopically approach disease in an English textbook were Hermann Pinkus and Amir Mehregan who in their 1969 book A Guide to Dermatohistopathology included concepts such as lichenoid tissue reactions and a periodic table of adnexal tumors. The next breakthrough was Bernie Ackerman's gold book Histologic Diagnosis of Inflammatory Skin Diseases: A Method by Pattern Analysis which was clearly the most important dermatopathology book of the last century, firmly establishing pattern diagnosis and providing a useful method for approaching unknown slides.

When David Elder and his colleagues at the University of Pennsylvania took over Walter Lever and Gundula Schaumberg-Lever's Histopathology of the Skin, they retained the traditional disease-oriented classification but also set about to produce a book which would simplify ‘Lever’, show skin reaction patterns and provide clinical–pathological correlations. I must confess that I spent little time looking at the first two editions of Atlas and Synopsis of Lever's Histopathology of the Skin, but when David sent me some PDF files from the 3rd edition to enhance my contribution to the upcoming 11th edition of the regular ‘Lever’, I was very impressed and obtained a copy of the atlas to study.

In his introduction to the First Edition of the Atlas, Elder pointed out the two major problems he hoped to address: (i) ‘provide at least one important example of essentially all reaction patterns in the skin’; (ii) ‘facilitate an understanding of the way in which different diseases [that is diseases covered in totally different chapters of a traditional book] may induce similar reaction patterns’, thus facilitating a more useful bundling of microscopic differential diagnosis lists. In addition, the Atlas includes clinical pictures and more extensive clinical summaries than found in the text. As an example, the first chapter deals with disorders of the epidermis and especially the stratum corneum. A representative subheading is B. Hyperkeratosis with normal or hypergranulosis. The two subdivisions are (i) no inflammation which includes several forms of ichthyosis and epidermodysplasia verruciformis and (ii) scant inflammation which includes lichen amyloidosis and macular amyloidosis. This simple example is enough to show the advantage of such an approach – the likelihood of reading about amyloidosis and ichthyosis when scanning a traditional dermatopathology text is almost zero, yet the differential diagnostic considerations are legitimate.

I will not inflict all the different categories on the reader, but suffice it to say that one moves through epidermal and melanocytic proliferations, diseases of the superficial cutaneous reactive unit (in essence superficial dermatitis) and into deeper lesions. The classification often become quite complex and is not always intuitive. For example, under superficial dermatitis with lichenoid infiltrates, there are subcategories based on lymphocytes only, lymphocytes predominantly, eosinophils, plasma cells, melanophages, histiocytes, mast cells and dermal fibroplasia. Is there ever an infiltrate that only has lymphocytes? I doubt it, but the category is nonetheless useful. Under lichenoid disorders, in addition to all the diseases we all consider lichenoid (lichen planus, lichenoid drug reaction, lichen nitidus, graft-vs.-host disease), other important microscopic differential points such as lichenoid keratosis and lichenoid actinic keratosis (I was glad to see them clearly separated), mycosis fungoides, secondary syphilis and urticaria pigmentosa are included.

Tumors have always been harder to approach in a pattern fashion. Ackerman always emphasized silhouettes to distinguished benign neoplasms from malignant ones, but then his system required one to recognize whether a tumor was follicular, apocrine, or eccrine – which was often a moving target as he revised his schemes. Elder and colleagues rely on cell types – small cell, large polygonal and round cell, spindle cell, pleomorphic and connective tissue – to approach tumors. The small cell tumors are all hematopoietic except for Merkel cell carcinoma; to my surprise, no adnexal tumor is small cell. Panniculitis is probably the easiest disease to approach microscopically but at the same time one of the hardest to diagnosis clinically; here the standard lobular vs. diffuse approach is used.

Technically, the most outstanding feature of the Atlas is the perfect photomicrographs. I have never seen such pristine low power views as those here; Elder tells me they were obtained by digital scanning of slides for virtual microscopy. When I think of all my unsuccessful attempts over the years to take sharp low-power views, I can only congratulate the authors on finally solving that problem. The images at higher magnification views are equally good and the combination of detailed legends and key features highlighted by block text and arrows make the pathological illustrations didactically superb. I wish I could say the same for the clinical photographs. Today I receive many sharp clinical pictures from around the world from colleagues – all taken on iPhones or similar devices. Digital cameras are even more flexible. Three of the six authors are clinicians; I challenge them to move the clinical photographs into the same quality league as their dermatopathology colleagues have brought the photomicrographs. We all are aware of how it is sometimes hard to get perfect pictures of rare diseases, but the illustrations of plaque psoriasis or lichen planus say it all. Despite their variable quality, the clinical pictures greatly enhance the Atlas and give those coming from a pathology background a feel for what is seen in the examining room.

I think the value of this book can be answered simply. If you were to give one group a residents a copy of the standard Lever text and another group a copy of the Atlas, who would be better at interpreting slides after a month's rotation on dermatopathology or through regular participation in teaching conferences. I am convinced the Atlas is clearly a better way to start and commend it to all young dermatologists and pathologists.