Histiocytoma?- Fibroblastoma?- Fibrohistiocytoma-Vascular tumor?
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Richard J. Reed, M.D. (Jan. 2004)
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In the historical concepts of the histiocyte, a cell of hematopoietic origin has evolved from a cell of dubious nature to one of a pluripotent nature. As a “wandering macrophage,” a histiocyte is a most efficient phagocytic cell with the ability to engulf particles; it is defined by its ability to engulf particles of a certain size. It also has become a “dendritic cell;” in one guise, it has a role in the immune response, and has the ability to affect the homing of lymphoid cells. In another guise, it seems to have a role in the activation of connective tissue, particularly in the expression of mucinous components of connective tissue. These recent additions are conceptually useful. Histiocytes, in these useful, conceptualized roles, are assigned importance in a variety of immunological interactions. In yet another conceptualization, histiocytes function as “facultative fibroblasts” (I suspect that it is more likely that on occasion fibroblasts function as facultative histiocytes). In this approach, some numbers of proliferating histiocytes, having been recently recruited to a site of injury or inflammation, or having been neoplastically initiated, phenotypically transform to function as fibroblasts. They produce respectively either a reactive, or a tumor stroma; lesions, in this “facultative” (conceptual) role, display a biphasic quality; conceptually, a single line of cells functions as a system of cells (all derived from a basic progenitor cell).
The qualifier, epithelioid, has become intimately related to the concept of the histiocyte; the epithelioid histiocyte of tubercle-like granulomas is well recognized. Definitions of histiocytoid qualities, and those of epithelioid qualities have evolved to the point that it is often convenient to think of cells with histiocytic qualities as also having epithelioid qualities. The qualifier, epithelioid, initially gave recognition to patterns in which cells closely cluster without an intervening fibrous matrix among individual cells; it gave recognition to cells which are mutually dependent on, and in their activities require close contact with, their neighbors. Both round cells and spindle cells can be characterized as epithelioid cells, if encountered in the requisite patterns. Promoters of the concept of fibrous histiocytoma (and malignant variants) extended the definition of epithelioid to embrace the contours of individual cells; a round, plump cell was an epithelioid cell. In the latter approach, it seems somewhat redundant to characterize a histiocytic neoplasm as also being epithelioid. Bliss and Reed in their definition of “large cell sarcoma” implied that the cell of origin was a synoviocyte and, as such, the lesion had histiocytic qualities. Enzinger, in a play on words and concepts, preferred the designation, “epithelioid sarcoma;” he did not consider the lesion as having a relationship with synovial histiocytes.
The measure of a concept is utility; for many years, the concept of fibrous histiocytoma afforded great utility. Immunohistochemical studies have compromised the concept of a histiocyte in the role of a facultative fibroblast; in the face of contradictory evidence, some observers, on occasion, and when conceptually conventient, still promote the concept of fibrous histiocytoma in the classical manner. On the other hand, the concept, with certain alterations and adjustments, retains application, if dendritic histiocytes are richly distributed in a fibrous matrix, and among fibroblastic cells. The reader of all promotions of a fibrohistiocytic neoplasm should carefully evaluate the contributors intentions as regard the relationships of histiocytes to fibroblasts. In such lesions, it is often difficult to identify which of the two cell lines is the neoplastic one. In many common dermatofibromas, atypia is often more pronounced in the “histiocytic” component; the atypia would then implicate the histiocytic line as the neoplastic component. Other examples are remarkably fibroblastic to the relative exclusion of histiocytic components. In thinking about both the ease with which “new” fibrohistiocytic neoplasms aredefined and introduced, and the uncritical approach of reviewers - whose duty is to question the concepts of contributors - I am tempted to paraphase a question often posed by Jimmy Durante: “Did you ever have the feeling that you wanted to go but still have the feeling that you wanted to stay”...................? (or something to that effect).
Fifty years of engagement in any field lends a perspective; in the field of pathology, fifty years of practice is a progression toward a condition of isolation; the contemporaries of such a practitioner will be mostly retired (and wondering why the old fool doesn’t do the same), or will have passed on.
Accommodations are required for individual perspectives. Utility can take precedence over individual perspectives. That the concept of malignant fibrous histiocytoma could dominate the category of soft tissue tumors for approximately 40 years is clearly an illustration of the effects of utility on perspective; it became a convenience by which a variety of soft tissue tumors could all be assigned to a single treatment regimen. In the category of dermatofibroma, I believe this same sacrifice, in the name of utility, made the promotion of the concept dermal dendrocytoma briefly acceptable. This sacrifice can easily become a habit. In submitting to the habit, it is easy to characterize a tumor with epithelioid cells and dendritic histiocytes (the latter being immunoreactive for XIIIa) as some variant of histiocytoma or fibrous histiocytoma. In this submission, variations in distribution and intensity of cytoplasmic staining may be viewed as an expression of problems in technique and in the preservation of tissue. If one group sees mucinous components that have not been recorded in the observations of others, in what manner is the first group to reconcile the differences? Should the differences be recorded in the literature so that other observers with other perspectives and techniques can sort out the differences?
My recogition of real and virtual images may evoke attitudes and opinions (i.e., a perspective) which differ greatly from those of other observers. Work which three of us did in the late 1980’s and early 1990’s led to interpretations of a problem lesion. Our interpretations differed greatly from the opinions recorded in the literature. We documented our approach and submitted the material for publication. The contribution was rejected with a recommendation that we reconcile our results with those current in the literature. I did not consider the reviewers’ opinion to be unbiased. I set our material aside with the impression that the rejection was based in politics rather than scientific honesty.
ANOTHER CATEGORY GREATLY INFLUENCED BY PERSPECTIVE:
On this site, a study of a group of uncommon skin lesions is presented. The end of the study was in 1992-93. At that time, this material was submitted for publication, but two reviewers rejected it. The rejections were so similar that collusion might be suspected but, surely, the editorial policy of a respected journal would not tolerate such a violation of standards. In the rejected material, a perspective, which contradicted the prevailing approach, was developed (might the contradiction have formed the basis for a rejection?). What is published on this site represents a rearrangement of material after the rejection, but the revised material was not submitted to another journal. The material has not been updated to include other pertinent references, but such references are available in common textbooks. The Critique includes recent revisions. The materials from which this SECTION was structured were all lost in the aftermath of Katrina.
In part, a conviction, that it would be difficult to find a home for this material, was founded on a belief that editorial policy is not immune to political influences. At one time, the senior author would not have experienced difficulty in finding a receptive journal but favor, even in editorial policy, is fleeting. As a young man, I might have attempted to search about to find a home for this material. Very few of my efforts have failed to find a home. One study in the early 1960’s of 100 cases of carcinoma of the thyroid from the files of Charity Hospital (with great effort by Beau Burch in searching out material from the files, and follow-up from the Tumor Registry) never found a home. My chairman, with greater allegiance to his former teacher than to me, suggested that I should set it aside. I never gave him the privilege, or task, of reviewing another manuscript for me. There are a few published contributions which I might withdraw, if given the opportunity. One example was cited by one reviewer as “excellent,” and by another reviewer as the “worst he had reviewed.” The editor, being a friend, accepted the article for publication; I am not sure he did me a favor. The attitude of editors is a two-way street. Confidence has a role in the structuring of a manuscript, and even in its acceptance. At my age, my judgment may be open to question. Certainly, the last article I submitted for publication was treated in a high-handed manner suggesting that I am too senile to even respond to the criticisms of a reviewer; the manuscript and photomicrographs were “lost.”
At this web address in this Section, the category in question is that of fibrous histiocytomas. An interested party with a good background in general pathology would not have to spend much time with A. P. Stout’s contribution of “facultative histiocytes” to turn away with a conviction that, at least in part, Stout was studying lymphomas. The technique of cell culture for the demonstration of the facultative transformation of histiocytes into fibrocytes is fraught with errors. The common approach to the category of fibrous histiocytoma is more of a linguistic compromise (a compromise which has proved to have practical utility) than a conviction that histiocytes facultatively function as fibroblasts. The evidence that two cell lines function in concert, even though one cell-line may be neoplastic, is more acceptable. The observation, that both cell lines have dendritic qualities, is hardly a basis for the definition of a system of genetically diverse cells in which the unifier is dendritic outlines. The articles which relate to the material on this site are variably titled, either as epithelioid cell histiocytoma, or epithelioid benign fibrous histiocytoma. Additional references are included. The references in Chapter 5 are not listed in a consistent fashion. I don’t feel like sorting the references, as I might have to do to satisfy an editor. In this format, I don’t have to conform to what some reviewer might think is a proper construction; I don’t have explain why I studied this lesion; I don’t have to reconcile my conclusions with those previously published.
After all this time, why resurrect this material? A lot of work went into the manuscript; the conceptual approach at the time was relatively unique. Finally, a recent contribution revised my interest in the material. In this recent contribution, the conceptual approach differs and yet, the results, if not the conclusions, seem to support what we proposed 10 years ago.
In the following presentation, the typos, the rambling, the acerbity, the incoherence and the diffuseness of the presentation are all the work of the senior author; Don and Syed are not to blame.
Adventitial myxofibroblastoma (Reed, RJ, Pulitzer, D, and Hoda, S)
Adventitial cellular myxofibroblastoma is an uncommon lesion of the skin with a clear preference for the adventitial dermis and acral sites (recently this anatomic restriction has been questioned). In the most characteristic gross configuration, it is polypoid or mushroom-shaped. Generally, the interface with the adjacent dermis is sharply defined. Some examples are prominently “myxomatous” (this word conveys a quality that is lacking in the designation, “myxoid”), some are uniformly cellular, and some have a fibrous quality. Cytologic features are distinctive. Some variant lesions, which expand into the reticular dermis, and are uniformly myxomatous, may be related to the classic lesion of the papillary dermis. For these variant lesions, reservations regarding an identity with the more characteristic lesions should be entertained. A few of the more cellular, uniformly myxomatous examples are not associated with a conspicuous plexus of vessels. For such lesions, the distinctions between myxoma and adventitial cellular myxofibroblastoma are difficult to define. In the definition of this lesion, the diverse potentials of fibroblasts, and the interplay of fibroblasts and histiocytes, are manifested. A recent contribution relating to myopericytomas, documents histologic patterns in at least one example that remarkably resemble those of some examples of “adventitial myxofibroblastoma.”