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Basaloid/follicular hyperplasia overlying connective tissue/mesenchymal hamartomas simulating basal cell carcinomas,☆☆,,★★

https://doi.org/10.1067/mjd.2001.117727Get rights and content

Abstract

Background: Basaloid hyperplasia has been described overlying dermatofibromas as well as in the epidermis overlying nevus sebaceus. Although the morphology of these areas may resemble that of basal cell carcinoma (BCC), in the majority of cases aggressive behavior of the proliferation is not seen. In fact, the basaloid proliferation often shows follicular differentiation and may be stimulated and maintained by its relationship with the underlying stromal cells. Objective: We wanted to determine whether immunohistochemical staining for antibodies, which may suggest differences in pathogenesis, were different in basaloid hyperplasia overlying connective tissue/mesenchymal hamartomas and BCC. Methods: We report 3 cases of connective tissue/mesenchymal hamartomas with overlying basaloid hyperplasia, in which the areas of the basaloid proliferation showed follicular differentiation. Immunohistochemical stains included Ber-EP4, PCNA, Ki-67, Bcl-2, p53, SM-Actin, CD31, factor XIIIa, KP-1, and CD34. Results: There was a diffuse positive reaction for Ber-EP4 in all specimens and there was increased nuclear staining for PCNA and Ki-67. There was focal cytoplasmic staining for Bcl-2 in the areas of basaloid hyperplasia. Immunohistochemical staining for p53 showed only scattered positive cells except in a small focus in the areas of basaloid hyperplasia. The connective tissue component of all lesions showed diffuse staining for CD34 surrounding areas of basaloid hyperplasia in the mesenchymal component as well as in abundant S-100+ nerves. Conclusion: The areas of basaloid hyperplasia in these hamartomas exhibited an immature phenotype similar to that seen in both BCCs and follicular tumors; however, the patterns of proliferation markers, p53, Bcl-2, and the surrounding stromal cell markers were similar to those of benign follicular tumors. Thus the staining pattern for this group of antibodies suggests that areas of basaloid hyperplasia are not BCC. (J Am Acad Dermatol 2001;45:886-91.)

Section snippets

Material and methods

Three patients had lesions that had been present for decades (Table I).

. Patients with connective tissue/mesenchymal hamartomas with overlying basaloid hyperplasia

Patient No.Age (y)/Sex/RaceLocationSize (cm)Duration (y)
171/F/WLeft lateral ant low leg3>40
280/F/WRight forehead5 × 640-50
342/F/WRight ant chest4 × 5 cm>30

Ant, Anterior; F, female; M, male; W, white.

The first patient had a depressed plaque on the lateral leg with slight hyperpigmentation and superficial scale (Fig 1).

. Depressed plaque

Discussion

We are not aware of any previous reports of basaloid hyperplasia overlying connective tissue/mesenchymal hamartomas. We believe that these hamartomas are distinct from NS and dermatofibromas with areas of basaloid hyperplasia. NS has been associated with multiple ectodermal and mesodermal malformations including other cutaneous hamartomas.2 However, unlike most reports of NS, the lesions in this report were not noticed until later in life, and they did not become verrucous. Only case 1 showed a

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The opinions or assertions herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy, the Department of the Army, or the Department of Defense.

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Reprints not available from authors.

*Drs Skelton and Smith are now with Dermatopathology, Departments of Dermatology and Pathology, University of Alabama at Birmingham.

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**Dr Corbett is now practicing in Wilson, North Carolina.

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