Dermatopathology: Practical & Conceptual

October – December 2010 | Volume 16, No. 4


François Milette


It is a sad story, the story of primary acquired melanosis and a sad story, too, is that of this series of articles on the subject.

What was our intent when we undertook this Arbeit? We wanted to review, in the most collegial and open-minded spirit possible, the subject of melanocytic proliferations of the conjunctiva in order to see whether these neoplasms deserve an approach different from that used in the evaluation of melanocytic lesions of the skin and, more specifically, of malignant melanocytic proliferations that develop in actinically damaged skin, the so-called lentigo maligna.

In order to achieve this goal we proceeded in our usual exegetic manner, going through the history of melanoma in situ, of lentigo maligna and, finally of primary acquired melanosis itself. An exhaustive review of the literature was done and as we proceeded it became constantly more evident that what is called primary acquired melanosis is, in virtually every case, melanoma in situ. The very same characteristics were illustrated clearly in the articles advocating the concept of primary acquired melanosis as those now considered universally as characteristics of melanoma in situ when found in the skin.

After having completed this review, we collected cases of our own of primary acquired melanosis and, once again, the histological and cytological characteristics appeared to us as diagnostic, screamingly diagnostic, of melanoma.

At the end of this journey, therefore, the only conclusion we can arrive at is the following: primary acquired melanosis as described in the literature and, as observed in the few cases we collected, is melanoma in situ in virtually every instance. A few images are not conclusive so that it cannot be stated with certainty whether benign lesions were also included under the designation. In fact it is probable that various kinds of lesions are included under the title of “benign acquired melanosis without atypia.” This has yet to be elucidated. While doubtlessly some areas of single melanocytes in melanoma in situ or of regression of melanoma in situ have been diagnosed as “acquired melanosis without atypia” the same diagnosis also was given to entirely benign lesions, such as junctional nevi and racial melanosis. It appears that we are touching here the limits of diagnostic possibilities, but concepts such as primary acquired melanosis in no way clarify the situation. All to the contrary, they blur it still more just as do, in pathology of the skin, concepts such as melanocytic dysplasia, superficial atypical melanocytic proliferation, melanocytic proliferation of unknown significance, de novo intra-epithelial melanocytic dysplasia, etc., etc., etc. This conclusion is crystal clear to us after reviewing extensively the literature pertaining to these various evasions from uncertainty or from a clear diagnosis of melanoma in difficult cases.

Hopes are often placed in molecular biology as a promising tool for differentiating benign (innocuous) melanocytic lesions from malignant (life-threatening) ones. Our sharing of these hopes is limited. How could it be possible to define molecular signature of malignancy/benignancy while resting on the paradigm accepting the possibility of neoplasia being neither benign nor malignant? The chances are that molecular biology data derived from the study of primary acquired melanosis or of any other lesion of unknown significance or unknown malignant potential, be it from the skin or the conjunctiva, will bring only conclusions of unknown significance, only more confusion.

We think that our arguments, developed extensively in these pages, are compelling, and we hope that they will convince the reader, but we are worried for several reasons:

Numerous colleagues, ophthalmologists and ophthalmopathologists, were contacted by Dr. Ackerman over the course of two years, but hardly any of them was willing to share biopsy specimens of pigmented lesions from his own experience. Most of the time our repeated efforts to obtain cases of primary acquired melanosis from colleagues ophtalmopathologists were systematically and cavalierly rejected, the essence of the answers we obtained being adequately summarized thus: “Mind your own business.” This answer at first induced anger, but even after anger was dissipated, frustration remained because it would have been great to review a number of cases larger than the mere five we finally collected. Most of these five cases were submitted by ophthalmologists or general pathologists that sent them to us as unusual cases in their practice. They thought that, as dermatopathologists, we had the greatest expertise concerning melanocytic lesions; we think they were right but, of course, not everybody will agree with this statement! In any event, it is from them that we derived the motivation to pursue our undertaking and we are grateful beyond measure. We wish here to stress this gratitude.

Beyond our frustration born from the difficulties in obtaining cases, sadness was induced by the observation that collegiality is disappearing in pathology. Different subspecialties are working more and more as in separate towers of glass, and they can communicate no more without risking a catastrophic break of their authority. At no time in our careers was this lack of collegiality made more evident to us than during our work on the present series of articles.

We can add here that even though we regret having met up with the refusal to share information, we understand clearly the good intention behind the concept of primary acquired melanosis. The aim is to avoid overtreatment by mutilating surgery of lesions that evolve slowly and cause death relatively rarely. This same argument was invoked repeatedly against the notion that lentigo maligna of the skin is melanoma in situ. In the case of lentigo maligna, overtreatment meant disfiguration. In the case of primary acquired melanosis, it means blindness, and as one author stated: “better death than blindness.” But this argument is devoid of sense. Compassion for the fears of patients changes nothing of the nature of a neoplasm! Treatment must be planned on the basis of a clear and consistent diagnosis. Diagnosis is not to be coined in order to fit treatment choice or patients’ fears!

Who has ever seen a superficial basal cell carcinoma causing death? Nobody! But it has never been proposed to change the term “superficial basal cell carcinoma” by an oddity such as “primary acquired basalosis”! Why? Because the natural history of this entity is well understood and because when a patient expresses his fear of the term “carcinoma” the clinician can explain clearly that the meaning of it is not necessarily dreadful. The same should be true for melanoma in situ. The choice is not merely between death and blindness. Other alternatives exist!

In the ultimate, it is for the reader to decide for himself. For our part, we will welcome any critic or comment concerning this series and we will answer them to the best of our ability.

It is not possible to conclude this series without evoking the memory of one of us who left for a better world during its realization: our friend Bernie. We find no better way to honor his memory than to give Bernie Ackerman these last words. The following is a transcription, verbatim, of a message by him left on the voice mailbox of one of us (Almut Böer) on November 23, 2008, a few days before his unexpected death in December of the same year. It probably can be considered his swan song, and it summarizes perfectly this series of articles and our opinion concerning primary acquired melanosis:

“Almut. I don’t know whether you’re in Germany or in Spain, but wherever you are I hope you’re enjoying it. I’m about halfway through the illustrations of your chapter about primary acquired melanosis and virtually every photomicrograph shows melanoma in situ. I’m rewording the legends making them brief and consistent. When we speak next we’ll decide how much detail should be given to why each of them is melanoma in situ. It becomes quite repetitive after a while, and of course there are changes very different from very early, when there’re solitary melanocytes only too many nests of melanocytes. So we can get back to that. But I think that it really tells an incredible story, the material that you’ve culled and that story is that primary acquired melanosis with and without atypia is melanoma in situ. Bye now!”

Bye now!

Francois Milette, M.D., is a pathologist from Centre Hospitalier Pierre-Boucher in Longueuil, Canada. Contact corresponding author via email: francois.milette@cssspb.qc.ca .