Differential Diagnosis and Management on Seborrheic Keratosis in Elderly Patients

Abstract

Seborrheic keratoses are exceedingly common in the elderly and usually are easy to diagnose and do not require treatment. However, given their great variety of clinical presentation, they may give rise to false-positive cases, meaning that they may at times mimic melanoma, squamous cell carcinoma and basal cell carcinoma. On the other hand, melanoma may mimic seborrheic keratosis, leading to incorrect patient management. With this review, we would like to summarize the current knowledge about epidemiology, clinical, dermoscopic and reflectance confocal microscopy imaging of this common entity, and we also summarize the currently available treatment options.

Keywords: basal cell carcinoma; dermoscopy; elderly; melanoma; reflectance confocal microscopy; seborrheic keratosis.

Figure 1

Clinical, dermoscopy, RCM and histology of an acanthotic SK. (A) Clinical overview of the back of one 70-year-old man with multiple SKs. (B) Dermoscopy of one lesion, multiple milia-like cysts (white arrows) and comedo-like openings (red arrows) are visible. (C) RCM imaging at the level of the supra basal layer, enlarged inter papillary spaces are visible, with horn pseudocysts (white arrows) corresponding to milia-like cysts. The red arrow points a more superficial epidermal invagination filled with keratin, corresponding to a comedo-like opening in histology. (D) Histology showing acanthosis of epidermis and epidermal invaginations filled with keratin (hematoxylin and eosin stain, original magnification 100x).

Figure 2

Hyperkeratotic SK. (A) Clinical close up of a brownish pigmented papule with a crusty surface. (B) In dermoscopy a brain-like appearance is visible. (C) RCM mosaic (5×4 mm) showing multiple epidermal invaginations giving rise to sulci and gyri corresponding to the dermoscopic cerebriform surface.

Figure 3

Hyperkeratotic SK. (A) Dermoscopy showing multiple fat fingers, a variation on the theme of cerebriform surface. (B) Corresponding RCM mosaic (5×3 mm) showing the lesion surface with multiple sulci and gyri.

Figure 4

Adenoid or reticulated SK. (A) Dermoscopy of a lesion located on sun-damaged facial skin. A pseudo network is visible with well-demarcated borders. (B) In RCM, numerous bulbous projections at the level of DEJ and the so-called “cord like appearance” are seen. (C) Histology showing a basaloid epidermal proliferation arranged in thin, branched and intersected epithelial tracts (hematoxylin and eosin stain, original magnification 200x).

Figure 5

Clonal SK. (A) Dermoscopy with multiple grey blue globule like structures. This variant is difficult to differentiate from a pigmented basal cell carcinoma (B) RCM showing nests of epithelial cells. (C) Histology showing a basaloid epidermal proliferation characterized by acanthosis and horn pseudocyst. Melanin pigment is present in some cells. An intraepithelial roundish nest of epithelial cells is visible (Borst-Jadassohn phenomenon) (hematoxylin and eosin stain, original magnification 100x).

Figure 6

Irritated SK on the leg of a 76-year-old man. (A) Clinically the lesion is a large plaque with a partially keratotic surface, well-demarcated borders and color variegation from light brown to dark brown. (B) In dermoscopy a brown network is seen, with well-demarcated borders. In the non-pigmented area multiple dotted and hairpin vessels are visible surrounded by a whitish halo.

Figure 7

Melanoacanthoma. (A) A solitary dark papule on the abdomen of a 68-year-old man. (B) Close-up clinical image that shows the hyperkeratotic surface of the lesion. (C) In dermoscopy the lesion appears heavily pigmented, with peripheral streaks and a central hyperkeratosis. (D) RCM image at the level of the DEJ showing enlarged inter papillary spaces and multiple pseudo horn cysts. (E) Histology showing an SK with diffuse melanin pigmentation and colonization by melanocytes (hematoxylin and eosin, original magnification 200x).

Figure 8

Melanoma mimicking an SK with regression. (A) Clinical view on the trunk of a 77-year-old man. (B) Close up showing a small dark brown, partially keratotic macule. (C) In dermoscopy the lesion is asymmetric, with a peripheral area with hyperkeratosis and the rest of the lesion showing grey color and peppering. The lesion was excised, histology revealed a in situ melanoma with regression.

Figure 9

Melanoma mimicking an irritated SK. (A) Clinical view of the back of a 78-year-old man with multiple SKs, cherry angiomas and nevi. (B) Clinical close-up image, the lesion appears erythematous and not well defined. (C) In dermoscopy dotted vessels are visible over the entire lesion area (white arrows). Scales and crust are present on the surface.

Figure 10

RCM and histologic imaging of the case in Figure 9. (A) RCM at the level of the spinous layer showing bright dendritic cells. (B) Histology showing an irregular and asymmetrical junctional proliferation of melanocytes, characterized by consumption of thinned epidermis and a dense dermal lymphocytic infiltration. Some epidermal invaginations filled with keratin are evident on the right (hematoxylin and eosin stain, original magnification 40x). (C) RCM mosaic at the level of the DEJ showing non edged papillae and meshwork pattern. (D) Histology showing atypical melanocytes arranged in a lentiginous pattern and confluent irregular nests (hematoxylin and eosin stain, original magnification 200x)(Figure 10, Figure 11).

Figure 11

Invasive melanoma on the abdomen of an 81-year-old man. (A) The patient had multiple nevi and multiple SKs. All lesions were examined with dermoscopy, also the “hidden” ones. (B) Close up of the 7 mm macule finally diagnosed as melanoma. (C) In dermoscopy asymmetry and irregular globules are seen. Histologically a diagnosis of 0.6 mm Breslow thickness melanoma was rendered.

Figure 12

SK mimicking melanoma. (A) Multiple solar lentigos and SKs on the back of a 69-year-old man. (B) One larger, outstanding macule with color variegation. (C) In dermoscopy, the lesion is characterized by a very regular network, with well demarcated and moth-eaten borders. Hyperkeratosis can be seen on the lesion surface.