J Cutan Pathol 2008: 35: 89Blackwell Munksgaard. Printed in Singapore

Copyright # Blackwell Munksgaard 2007

Journal of

Cutaneous Pathology

Letter to the Editor

ReplyTo the Editor,I believe that Dr Francois Milette has completely

missed the purpose of the paper by Doctors Davis andZembowicz (1). Themain gist ofDrMilette’s argument,as summarized in his concluding remarks, is that theauthors misdiagnosed melanoma in situ as a junctionalnevus and that the authors have concocted newdiagnostic terminology to hide their diagnoses or coverthem up. This reductionist position is simplistic at bestand anti-progressive at worst. Dr. Milette’s view that allthese cases outlined in the paper are diagnosticallystraightforward and easily diagnosed as melanoma insitu, completely nullifies the reality of the field ofmelanocytic lesions in which atypical lentiginousmelanocytic proliferations are difficult to classify. If onewere to simply classify all these lesions as melanoma, Ibelieve that we truly would have an epidemiologicalexplosion of case reports of melanomas. Doctors Davisand Zembowicz have attempted to generate criteria fora subset of atypical lentiginous melanocytic prolifer-ations which if left alone, will continue to persist andprogress, thus behaving in a malignant fashion. DrMilette disagrees with the criteria proposed in table 2 asnegative and irrelevant. The criteria generated in thetable reflect an attempt to reproduce reliable criteria fordiagnosing these problematic lesions. I do agree withDrMilette’s query of the use of the term �floating’ abovethebasal layerof the epidermis.However, the remainderof the criteria does provide a framework around whichto analyze similar lesions.DrMilette’s contention that the images in fig. 1 are

all diagnostic of melanoma in situ is puzzling. Firstly,fig. 1 is divided into three time periods over which theproliferation appears to increase in cellularity, how-ever, the overall picture is that of an atypicallentiginous junctional proliferation. There is no solarelastosis or effacement of the retiform epidermis,changes seen in lentigo maligna, or the typicalshotgun appearance of malignant melanoma of thesuperficial spreading type. I therefore, think that theseare not diagnostically straightforward or typical ofmelanoma in situ as previously classified. Dr Milette’spoint that only high magnifications are shown is welltaken and the authors perhapswould have been betterserved to submit more low-power fields. In fig. 2, thecaption does state that it is a Level 2melanoma, whichis in agreement with what DrMilette has ascertained.

With regards to the biological behavior, it isprecisely this fact that has led the authors to maintainthat these lesions do indeed behave in a malignantfashion. The time course of 12 years for their index todevelop into invasive melanoma, is precisely whatlead the authors to conclude that these were indeeda melanoma, and most probably a variant of a lentigomaligna. Our experience was indeed similar withthree of our index cases being initially diagnosed asatypical lentiginous nevi and the lesions persisting andprogressing over long periods of time (2).

In summary, the well-recognized patterns of cutane-ousmelanoma, namely, lentigomaligna type, superficialspreading type and acral lentiginous type, are well-defined in the literature, and for themost part are readilyrecognized as malignant melanoma. However, thereexist a substantial number of cases in which atypicallentiginous melanocytic proliferations are identified,and in which the lesions do not precisely fit into therecognized histologic patterns that we recognize asmalignant melanoma. I believe that as histopathologistsand scientists, it is our responsibility to attempt to furtherclassify these lesions and to determine their biologicalbehavior. I believe that Doctors Davis and Zembowiczhave defined a subset of such lesions, which if leftuntreatedwill persist and progress asmelanomas.Theselesions most probably represent a variant of lentigomaligna. Dr Milette is incorrect in his contention thatthese lesions were mistakenly diagnosed as junctionalnevi when in fact they were always melanomas in situs,and therefore readily recognized from the outset. Theselesions in fact donot conformtoanyof the criteria for thewell-known histologic subtypes of melanoma, and onlywith careful follow-up, monitoring of the progression ofthese lesions, and generation of histologic criteria, canwe proceed to label these lesions as melanoma, asoutlined by Doctors Davis and Zembowicz. To simplysay that all lentiginous melanocytic lesions are mela-nomas is tantamount saying that all sebaceous lesionsshould be called sebaceous carcinomas.

Roy King, MDKnoxville Dermatopathology Laboratory and

Departments of Pathology, University of Tennessee,Graduate School of Medicine, Knoxville, and

Vanderbilt University, Nashville, TN, USAemail: rking@labpath.com

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