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Richard J. Reed, M.D.
Feb., 2004
12 Versailles Blvd.
New Orleans, LA 70112
Site: www.pathology-skin-rjreed.com
INTRODUCTION:
In a contribution (section) on this site, /spitzjuvmel.html, the controversy surrounding the nature of Spitz lesions is discussed. In the presentation on the latter site, it is proposed that the designation, “Spitz nevus,” fosters a group of inappropriate virtual images, all having to do with the qualities of a nevus. As an alternative, the designation, juvenile melanoma, might avoid many of the muddled concepts which have grown up around “Spitz” lesions; the evoked virtual images would then have to do with a special variant of melanocytic neoplasia - something apart from common melanoma. In this approach, “Spitz” lesions are assigned to a category of intermediate neoplasia - the same domain as the minimal deviation melanomas; juvenile melanoma would take on the qualities of MDM of the Spitz-like type (fig. c8t3P1).
The intermediate category is heterogeneous. It is composed in part of lesions which resemble the variant “nevi,” such as Spitz “nevus,” halo “nevus,” pigmented spindle cell “nevus,” combined “nevus,” etc. These variant “nevi” might be better characterized as melanocytomas. Thin, common melanomas, in which lesions are defined by physical dimensions with secondary attention to cytologic features, also belong to this intermediate category; to qualify in this variant category of the common melanomas, lesions must measure less than 1 mm in vertical dimensions.
In the system of logic related to intermediate neoplasia, the metastasizing “Spitz” lesions would not be assigned to the category of common melanoma. Although a metastasizing “Spitz” lesion elicits virtual images related to the biologic potentials of common melanomas, there are no definitive studies which define the biologic potentials of deviant Spitz-like lesions.
Herein, the presentation is basically in two parts. In the first section, features commonly emphasized, or variably accepted, as being within the conceptual domain of “Spitz nevus” are discussed. In the second section, patterns, which in a different system of logic have been promoted as typical of a special melanocytic neoplasm - minimal deviation melanoma of Spitz-like type - are given separate attention. To fully appreciate this different system of logic the reader must review the material on /spitzjuvmel.html.
In the classification of skin disorders, a nevus is a blemish; often it is congenital. Characteristically, a nevus is a rather stable lesion; it slowly attains a certain size. Having stablized in size it may, over the years, slowly involute, or may show changes in the external appearance; progressive neoplasms may arise in the setting of a nevus. The designation, nevus, has application to a variety of hamartomas representing diverse tissue lines, such as melanocytic, epithelial, vascular, and mesenchymal.
The “Spitz” lesions are not by nature truly nevoid. In addition, they are rarely associated with remnants of a pre-existing common melanocytic nevus. To characterize a “Spitz” lesion as a nevus, evokes images of a rather stable lesion, often with a history of having been present for years without a change in size. A potential for neoplastic progressions are implicit in the concept of a nevus but, generally, such a neoplasm shows progressive growth, and is often associated with a remnant of the precusor. The “Spitz” lesions generally are lesions of recent onset with a history of rapid growth.
Richard J. Reed, M.D. (23 Feb. 04)
New Orleans, La.
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