In nearly every article about keratosis lichenoides chronica (KLC) reference is made to two articles by M. Kaposi, one of them published in 1886 [1] and the other in 1895. [2] In 1886, Kaposi told of a patient who presented himself with widespread papules, nodules, and keloid-like streaks (Fig. 1A), the latter being most prominent on the extremities, the lower part of the abdomen, and the neck. Kaposi thought that the disease in his patient resembled lichen planus and, therefore, he named it "lichen ruber moniliformis." In his article were included drawings of findings histopathologic, but the changes pictured bear no resemblance to those of lichen planus (Fig. 1B).

When, in 1895, Kaposi published his article titled (translated from the German) "Once again: lichen ruber acuminatus and lichen ruber planus," confusion reigned about a designation, namely, "lichen planus," that was applied by dermatologists to more than one condition. Moreover, no criteria were available then to differentiate clearly lichen planus from pityriasis rubra pilaris. In his article, Kaposi attempted to separate a condition that he called "lichen ruber acuminatus (verrucosus et reticularis)" from lichen planus. He reported on two patients. One, a 27-year-old woman, had an exanthem consisting of numerous tiny papules that became confluent to assume linear and reticular outlines. (Fig. 2A) Some of those lesions reminded Kaposi of lichen planopilaris because of the infundibulocentricity of them and, to his eye, findings histopathologic that resembled those of lichen planus. Kaposi made the same diagnosis of "lichen ruber acuminatus (verrucosus et reticularis)" in another patient, a 10-year-old child, although lesions in that patient were very different from those in the first (Fig. 2B) patient he presented. Attributes clinical pictured by Kaposi show features of what is called atopic dermatitis and of keratosis pilaris. The drawings of changes in sections of tissue cut from biopsy specimens taken from the patients of Kaposi do not permit a diagnosis to be made with specificity, but the section from the 27-year-old woman shows a lichenoid infiltrate beneath an epidermis that at the periphery of the lesion is acanthotic and in the center atrophic. (Fig. 2C) The lesion is hyperkeratotic, being associated with parakeratosis arranged in fashion staggered. From the attributes pictured, it is conceivable that the 27-year-old woman had an authentic disease typified by an exanthem clinically and by a lichenoid dermatitis histopathologically, whereas the child seems to have had a different condition, "atopic dermatitis" in company with keratosis pilaris.

In his article of 1895, Kaposi made only a brief reference to his previous publication in 1886, and it is likely that he, himself, did not regard the maladies presented in both articles to be the same disease. Nevertheless, in many articles published by others subsequently the terms "lichen ruber moniliformis" and "lichen ruber acuminatus (verrucosus et reticularis)" were employed as synonyms.

Reference also is made often to a 1936 article by Wise and Rein. In it the authors shared their experience with a patient who, in their view, had the same condition described by Kaposi in his seminal article of 1886. [3] The authors studied sections of tissue cut from biopsy specimens taken from their patient, and they could not find any similarity to lichen planus. For that reason, they suggested the term "morbus moniliformis lichenoides" for the condition. The pictures in that article do not permit a diagnosis to be made with certainty, but the process in that patient seems to be very different from that in any of the patients written about by Kaposi. (Figs. 3A and B)

In 1938, Nekam told of a woman who had been a subject in the publication of Kaposi in 1895. [4] When the painting in the article by Kaposi is compared to the photographs in the article by Nekam, there are similarities, but also differences. (Fig. 4 A–E) The size and the shape of individual papules and the involvement of the face in the eruption is similar in images of both articles but Nekam pictured also, on an arm, keloid-like streaks that seem to have been induced by an assault external, rather than having been brought into being by a process eruptive. Nekam took note of hyperkeratosis of acrosyringia, which prompted him to propose the name "porokeratosis striata lichenoides" for the condition. In none of his photomicrographs, however, is a cornoid lamella pictured, a finding requisite for diagnosis of porokeratosis of any type. Taking into account all the pictorial material presented by Kaposi in 1895 and by Nekam in 1938, it remains difficult to integrate all of the aspects. Nonetheless, the findings histopathologic are those of lichenoid dermatitis, different from lichen planus.

The term "keratosis lichenoides chronica" was introduced in 1972 by Margolis, when he recorded the history, attributes morphologic, and course of a patient who for 15 years had an asymptomatic eruption that consisted at the outset of the eruption of discrete perifollicular papules but, during the course of the process, took on linear and reticular shapes. (Fig. 5 A–C) [5] The photomicrographs reveal a lichenoid dermatitis affected with parakeratosis. Although the photomicrographs do not allow a diagnosis to be rendered with confidence, the process seems to be different from both lichen planus and lupus erythematosus.

In 1984, Mehregan and coworkers reported on a patient who, in their view, had lesions that resembled closely the ones described by Kaposi in 1886. [6] The authors, however, observed changes histopathologic of a subepidermal blistering disease that tended to resolve with scarring and with formation of milia. (Figs. 6 A and B) They concluded that the disease in their patient, as well as in the one of Kaposi in 1886, was a type of inherited epidermolysis bullosa in which the linear and bizarre shapes of individual lesions were a consequence of their having come into being by the effects of trauma external. The authors made a distinction clear between the condition called by Kaposi "lichen ruber moniliformis" (1886) from the one described by Kaposi under the title "lichen ruber verrucosus et reticularis" (1895). They asserted that the latter should be regarded as a variant of lichen planus for which they suggested the designation keratosis lichenoides chronica (KLC), whereas the former, in their opinion, was one type of inherited epidermolysis bullosa.

Mention is made often by those engaged in the subject under consideration here to an article published in 1989 by Braun-Falco et al. [7] Those coworkers sought to review the literature pertinent to KLC and, in the effort, to share with readers their own experience with a patient they diagnosed with KLC. The 61-year old woman had an exanthem that consisted of macules, lichenoid papules, and keratotic plaques, some of which Braun-Falco et al. characterized as having a "bizarre" outline. (Figs. 7 A and B) Several photographs of lesions clinical were shown, but only two of them seemed to come from their own patient. Whereas the palms, soles, and mucous membranes of that patient were spared by the process, lesions that obviously came from another patient, a man, were situated on the palms, the glans, and the nail units. Braun-Falco and collaborators did not comment specifically on the fact that the lesions they captured for purposes illustrative came from different patients and thereby left readers with the false impression that all the lesions pictured represented manifestations clinical of one and the same disease in a single patient. In actuality, the lesions shown are so dissimilar clinically that it seems more likely that they represent two different diseases in two or more patients. Only a single photomicrograph of a section cut from a specimen taken from their patient was included in the article. Although the authors described a bandlike lymphohistiocytic infiltrate, the changes pictured are those of a perivascular dermatitis that largely spares the dermoepidermal interface. The epidermis is acanthotic and orthokeratotic in compact fashion. The findings are not diagnostic of any particular condition. Nonetheless, on the basis of their search of the literature, Braun-Falco and colleagues came to the conclusion that KLC is distinctive. They tried to forge criteria for diagnosis clinical of KLC and for differentiation of it from lichen planus, "Morbus Kyrle," "Morbus Reiter," and psoriasis, but they failed to demonstrate compellingly that their own patient really had KLC.

Other authors in their report of a case of KLC included a review of the literature dedicated to the subject in general but rarely did they assess critically the attributes clinical and histopathologic. [8, 9] Baran, Panizzon, and Goldberg endeavored to characterize changes of the nail in KLC, but all 11 supposed examples of it likely are not representative of a single disease. [10] Some authors who reviewed what has been written during the past 120 years came to the conclusion that KLC represented a variant of lichen planus, [11] while others were impressed by its similarities to lupus erythematosus. [12]

In 1995, Masouyé and Saurat analyzed reports of 50 patients who had been diagnosed with KLC and found that in only 40 of them were features clinical and findings histopathologic consonant with what they regarded as typical. [8] They did not make it clear, however, to which articles specifically they were referring. They said other patients who claimed to have KLC had either dystrophic epidermolysis bullosa or what they called "congenital ichthyosiform syndromes." They acknowledged that the condition in some patients diagnosed as having KLC was extremely difficult to classify. The authors did not have experience of their own with a patient with KLC and showed neither a picture of lesions clinical nor photomicrographs of findings histopathologic of KLC.

In 1997, in the journal Dermatopathology: Practical & Conceptual, Massi, Chiarelli, and Ackerman addressed the issue of KLC in perspective historical and in a manner more comprehensive and more analytic than had been undertaken before. [14] They compared changes clinical and histopathologic as pictured in 42 articles published between 1886 and 1997. The authors noted that Kaposi, in his original work published in 1886, showed a patient whose lesions clinical seemed to have been induced factitiously as evidenced by the bizarre shape of them. They averred that drawings of findings histopathologic were not those of lichen planus and they were struck, too, how dissimilar were the aspects morphologic in patients reported on by Kaposi in 1895 and in those he presented in 1886. In their view, the second patient of Kaposi, the child (Fig. 2B), more likely had atopic dermatitis in company with keratosis pilaris.

Massi and associates interpreted lesions in patients pictured in a number of articles on the subject of KLC as being brought about factitiously entirely and called attention to lesions induced in fashion analogous, i.e., from trauma external, in other diseases, e.g., epidermolysis bullosa. [1, 2, 5, 15–26] Images of those lesions thought to have been caused artefactually by patients said to have KLC were reprinted by Massi et al. Those lesions with shapes artefactual surely look very similar to each other and have shapes artificial. But other lesions clinical pictured in articles published prior to the Arbeit of Massi and coworkers do not have the appearance of ones created artificially. They appear to have erupted rather than having been brought into being by trauma external. [27–31] Massi et al. did not comment in detail on changes histopathologic that were pictured in articles previous and they elected to reprint photomicrographs from only three articles, about which they commented that the findings shown defy diagnosis with specificity. Massi and colleagues were correct in their assessment that many of the photomicrographs in articles about KLC are difficult to interpret because of factors technical, but despite that limitation, some of them show more than simply changes consequent to rubbing vigorously and scratching excitedly, namely, lichenoid dermatitis. [5, 12, 16, 20, 21,23] Massi et al. acknowledged that some patients written about under the title of KLC might have had an authentic disease underlying, such as lichen planus, discoid lupus erythematosus, psoriasis, or pityriasis rubra pilaris, on top of which signs of rubbing and scratching were imposed. The authors, however, provided no clue to which of the patients in particular might have had a primary process pathologic that was complicated by trauma external. No comment was made by Massi, Charelli, and Ackerman about the attributes clinical and histopathologic pictured in several reports about KLC that do not seem to correspond to any well defined disease, but were similar to each other and were marked by distinctive lichenoid dermatitis.

Ackerman, then Editor of Dermatopathology: Practical & Conceptual, encouraged colleagues to provide readers with examples of their own with KLC. In the very same issue of the journal an article can be found devoted to KLC by Ruben and LeBoit [32] and another by Aloi and Tomasini. [33] Ruben and LeBoit told of their experience with four patients diagnosed by them with KLC. [32] Unfortunately, the authors showed only a single photograph of lesions clinical and photomicrographs of one section of tissue from a biopsy specimen taken from that patient. No material pictorial of lesions in the other three patients was made available. The features clinical are subtle, but seem to consist of small papules that assumed shapes linear and reticular by way of confluence. The findings histopathologic are those of a lichenoid dermatitis centered on acrosyringia of eccrine units, peppered with neutrophils. These changes do not correspond precisely to any disease already established, and they are dissimilar from both lichen planus and lupus erythematosus. The authors also reviewed the literature dedicated to the subject of KLC and although they interpreted what was presented in 26 articles as being consonant with a specific disease, they neither indicated which articles in particular they were referring to nor identified the disease with exactness. Ruben and LeBoit concluded that KLC is an authentic disease but failed to demonstrate convincingly that all the four patients studied by them really had the same disease.

Tomasini and Aloi, too, had made the diagnosis of KLC in four patients and, based on their experience personal, concluded that KLC is a variant disseminated of an inflammatory verrucous epidermal nevus. [33] The authors illustrated their work with pictures of lesions clinical and with photomicrographs of sections of tissue from different patients. Alas, the authors did not attempt correlation clinicopathologic, patient by patient (Fig. 9 A–G). The lesions depicted by them do not seem to represent manifestations of a single process pathologic. The lesions pictured in Figs. 9A–C are similar to one another and appear to be infundibulocentric tending to become confluent with the assumption of shapes linear and reticular. Figs. 9D and E, however, show changes very different; infundibulocentric papules are absent. The photomicrographs in the article also show findings dissimilar: the changes in Fig. 9G are those of a lichenoid dermatitis covered with parakeratosis, whereas those in Fig. 9F portray only papillomatosis and orthokeratosis. Despite these differences profound, Tomasini and Aloi thought that all of their patients had one and the same disease. They failed to make clear which section pictured belonged to which lesion clinical. It can be surmised, however, that the section shown in Fig. 9H came from the patient pictured in Fig. 9 A–C.