Tumors of the epidermis

Tumors of surface epithelium.

Seborrhoeic keratoses are benign epidermal neoplasms that are rarely associated with other skin lesions especially malignancies. In this study, the aim was to assess the incidence of associated lesions occurring either adjacent to or contiguous with a seborrhoeic keratosis. A retrospective case series over a 12-month period was carried out. In total, 639 consecutive histologically diagnosed seborrhoeic keratoses were identified, of which 85 (9%) were found to be associated with other lesions. Of these associated lesions, 44 (7%) were malignant, with four of these found to be arising within the seborrhoeic keratosis. These associated lesions included premalignant lesions, malignancies, melanocytic lesions and miscellaneous lesions. Men (59%) were affected more commonly than women. The average age was 74 years (range 33-98 years). Seborrhoeic keratoses associated with other lesions were found most commonly on the head and neck. The incidence of associated lesions, in particular malignancy arising within seborrhoeic keratoses may be higher than previously thought. This may be an incidental phenomenon, or seborrhoeic keratosis could represent a precursor lesion. Therefore, seborrhoeic keratoses that have undergone recent clinical change should be considered for biopsy and histological examination.

Seborrhoeic keratoses with associated lesions: A retrospective analysis of 85 lesions

Importance Melanomas that clinically mimic seborrheic keratosis (SK) can delay diagnosis and adequate treatment. However, little is known about the value of dermoscopy in recognizing these difficult-to-diagnose melanomas. Objective To describe the dermoscopic features of SK-like melanomas to understand their clinical morphology. Design, Setting, and Participants This observational retrospective study used 134 clinical and dermoscopic images of histopathologically proven melanomas in 134 patients treated in 9 skin cancer centers in Spain, France, Italy, and Austria. Without knowledge that the definite diagnosis for all the lesions was melanoma, 2 dermoscopy-trained observers evaluated the clinical descriptions and 48 dermoscopic features (including all melanocytic and nonmelanocytic criteria) of all 134 images and classified each dermoscopically as SK or not SK. The total dermoscopy score and the 7-point checklist score were assessed. Images of the lesions and patient data were collected from July 15, 2013, through July 31, 2014. Main Outcomes and Measures Frequencies of specific morphologic patterns of (clinically and dermoscopically) SK-like melanomas, patient demographics, and interobserver agreement of criteria were evaluated. Results Of the 134 cases collected from 72 men and 61 women, all of whom were white and who had a mean (SD) age of 55.6 (17.5) years, 110 (82.1%) revealed dermoscopic features suggestive of melanoma, including pigment network (74 [55.2%]), blue-white veil (72 [53.7%]), globules and dots (68 [50.7%]), pseudopods or streaks (47 [35.1%]), and blue-black sign (43 [32.3%]). The remaining 24 cases (17.9%) were considered likely SKs, even by dermoscopy. Overall, lesions showed a scaly and hyperkeratotic surface (45 [33.6%]), yellowish keratin (42 [31.3%]), comedo-like openings (41 [30.5%]), and milia-like cysts (30 [22.4%]). The entire sample achieved a mean (SD) total dermoscopy score of 4.7 (1.6) and a 7-point checklist score of 4.4 (2.3), while dermoscopically SK-like melanomas achieved a total dermoscopy score of only 4.2 (1.3) and a 7-point checklist score of 2.0 (1.9), both in the range of benignity. The most helpful criteria in correctly diagnosing SK-like melanomas were the presence of blue-white veil, pseudopods or streaks, and pigment network. Multivariate analysis found only the blue-black sign to be significantly associated with a correct diagnosis, while hyperkeratosis and fissures and ridges were independent risk markers of dermoscopically SK-like melanomas. Conclusions and Relevance Seborrheic keratosis–like melanomas can be dermoscopically challenging, but the presence of the blue-black sign, pigment network, pseudopods or streaks, and/or blue-white veil, despite the presence of other SK features, allows the correct diagnosis of most of the difficult melanoma cases.

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Dermoscopic Clues for Diagnosing Melanomas That Resemble Seborrheic Keratosis

Background: Pseudoepitheliomatous hyperplasia (PEH) is a reactive epithelial proliferation that occurs in response to underlying infectious, inflammatory, and neoplastic conditions. The histologic features of PEH may simulate squamous cell carcinoma and may obscure an underlying malignant process. The association of PEH with benign melanocytic nevi is well described in the literature. However, reports documenting the association of PEH with melanoma are rare.



Methods:  We examined the demographic and histologic features in 13 cases of melanoma in association with PEH. In addition, we evaluated the possible pathogenic role of epidermal growth factor receptor (EGFR) using immunohistochemical methods.



Results:  In each case, histologic examination revealed epidermal hyperplasia with irregular cords of well-differentiated epithelial cells extending into the dermis and infiltrating the melanoma. Although overlap existed, two patterns of epidermal hyperplasia were noted. The majority of cases (69%) exhibited acanthosis, hyperkeratosis, papillomatosis, and irregular infiltrating epithelial cords with squamous eddies. The remaining cases demonstrated basaloid acanthosis, laminated orthokeratosis, and horn cysts. EGFR immunohistochemical studies revealed strong staining within the basal layer of the epithelium, with no discernible difference between the hyperplastic epithelium overlying the melanoma cells and adjacent normal skin. Immunostaining among the melanoma cells was absent to weak in each of the cases. All cases exhibited intense EGFR immunoreactivity in macrophages underlying the epidermal lesions.



Conclusions:  Melanoma is capable of presenting in a variety of histologic guises, including a pattern with PEH. The etiology of PEH, as rarely seen in conjunction with melanoma, unlikely involves EGFR and remains to be elucidated.

Melanoma associated with pseudoepitheliomatous hyperplasia: a case series and investigation into the role of epidermal growth factor receptor.

We report a case of malignant melanoma associated with seborrheic keratosis. This has been reported rarely in the literature, with disagreement regarding whether it is coincidental or whether malignant transformation occurs. Because seborrheic keratoses are common and association with malignant melanoma is very rare, we conclude that the association is coincidental. However, because of the association of other malignancies, a biopsy of any suspect or changing seborrheic keratosis is essential.

Robert J. Zabel

Papers

Malignant melanoma arising in a seborrheic keratosis