Seborrheic keratoses in five elderly patients: an appearance of raindrops and streams.

Five Chinese patients were found to have a linear, splayed, vertical pattern of lesions on their back, chest and abdomen. These lesions were clinically and pathologically diagnosed as seborrheic keratosis. The mean age of our patients was 77.6 years. During the follow-up period of 12-20 years, the lesions appeared to increase with age, and no malignant changes were observed on these sites. These patients had no serious underlying medical problems or malignant neoplasm, except for one patient with duodenal ulcer. While we are uncertain as to the cause of this patterning of seborrheic keratoses, we believe that it is distinct from previously reported patterns; this will contribute to research on the pathogenesis of seborrheic keratosis.

Introduction

Seborrheic keratosis is raised growths on the skin of older individuals. They usually start off with a light tan and then may darken to dark brown or nearly black. The consistent feature of seborrheic keratoses is their waxy, pasted-on or stuck-on look. The look is often compared to brown candle wax dropped onto the skin. The lesions can appear anywhere on the body, but most often occur on the face, chest, and back. There may be just one or clusters of dozens. As people age, they may simply develop more. We report a raindrop and stream pattern of seborrheic keratosis on the back, chest and abdomen of five Chinese elderly patients who had no seriously underline diseases or visceral malignancy during the follow-up period of 12–20 years.

Cases Report

Five Chinese patients, including four females and one male, sporadically had been referred to our clinic for asymptomatic but unattractive lesions on their backs, chest and abdomen. The lesions were characterized by multiple linear, spindle-or leaf-shaped eruptions that distributed linearly or radially in the direction of skin cleavage lines. The lesions were enlarged and spread slowly over time. Two patients complained slight itchy sensation on their lesions. Photographs of some lesions were taken [Figures 1–4] at the patients’ initial visits except for one patient who refused to have those lesions photographed.

Figures 1-4

The lesions of seborrheic keratosis on the back, chest and abdomen of four patients. Some lesions looked like clay or a blob of dirt “stuck” on the skin by someone. Their distribution displayed a pattern of raindrop and stream. The color of the lesions varied from pale brown with pink tones to dark brown or black

The mean age of onset in our patients was 59.2 years (from 52 to 65 years). The initial hematology tests, biochemistry tests and urinalysis revealed no abnormal data. Blood levels of carcinoembryonic antigen were within normal limits.

On physical examination, we observed that these lesions were sharply defined, light brown and flat papules and plaques with a velvety to finely verrucous surface, whose size varied from 1 mm to 1.5 cm in diameter. The distribution of lesions was unusual; some tended to follow skin cleavage lines on their backs and waists, and the arrangement of lesions was streamlined. Meanwhile, some lesions presented as raindrops that cross relaxed skin tension lines. The individual fully developed seborrheic keratoses displayed a deeply pigmented plaque showing obviously keratotic plugging of the surface.

Four biopsies from different patients were performed and the histology showed hyperkeratosis and acanthosis and horn cysts in the epidermis and chronic inflammatory reaction in dermis [Figures 5 and 6]. The stratum Malpighi showed moderate acanthosis caused by proliferation of squamous and basal cells. Rete ridges were usually elongated and interconnected.

Figures 5 and 6

Histopathological examination of skin biopsy showed acanthosis consisting primary of basaloid cells with hyperkeratosis and horn cysts (H and E stain, original magnification ×100)

During the 12–20 years of follow-up, these patients had no visceral malignancy, and only one patient had duodenal ulcer. New skin lesions continued to appear on their trunks; moreover, the third patient had developed a basal cell carcinoma on her left temple at the age of 66 years, 3 years after her visit to our department. Their clinical data are summarized in Table 1.

Table 1

Clinical data of the five patients with seborrheic keratosis

Discussion

Seborrheic keratosis is more common in populations with white skin compared to those having dark skin, and a sex difference does not appear to exist in the frequency of occurrence of seborrheic keratosis. The cause of seborrheic keratosis is unknown. They are mostly hereditary[1] and occur more frequently in sunlight exposed areas.[2] They may look like warts but they donot contain human papilloma viruses that cause warts. Clothing rubbing against can get them irritated and make them grow.

The lesions have a variety of clinical appearances and vary from macular form to papules and plaques with rough texture and waxy yellowish to dark brownish scaly surface. Sudden appearance of multiple eruptive seborrheic keratoses frequently suggests the Leser-Trélat sign,[3] which is associated most commonly with internal malignancy such as adenocarcinoma, especially of the gastrointestinal tract; however, an eruption of seborrheic keratoses may develop after an inflammatory dermatosis (eg, eczema, severe sunburn). The numbers of lesions on the trunks of our patients varied from 50 to over 100. Although the lesions are multiple, they increase gradually with age, and not suddenly. After 12–20 years of follow-up, no internal malignancy was found in these patients.

Our cases are of great interest for the pattern of their lesions. A variety of clinical appearance of seborrheic keratosis has been already reported. One case of multiple fibroepithelial basal cell carcinomas associated with seborrheic keratosis distributed in a neviform fashion has been described.[4] Another report was that of a 65-year-old woman who had multiple keratotic lesions distributed along skin cleavage lines on her lower back and waist.[5] Darjani and Ramezanpour[6] described a case of a 16-year-old woman who presented with itchy brownish lesions of seborrheic keratosis on the right side of her chest with dermatomal distribution for 2 years, and proposed that dermatomal seborrheic keratosis is a clinical variant. A 66-year-old Japanese man who had seborrheic keratosis following Blaschko's lines was also reported.[7]

Raindrop pattern of seborrheic keratosis on the back of elderly patients has been described by Hefferan and Khavari.[8] In their report, the lesions followed what appears to be a linear, splayed, vertical distribution. The mean age of their patients was 62.5 years and racial distribution included five Whites, one Black and one Hispanic; all the patients were males. The authors proposed that the distribution of their seborrheic keratoses may represent a response to repeated overhead or near-overhead sun exposure of the back, hence the near-vertical raindrop pattern. In contrast, our patients belonged to yellow race, without chronic sun exposure, and their lesions were located not only on the back but also on the chest and abdomen. The lesions on the body of our patients appeared like raindrops and streamlines. While we are uncertain as to the cause of this patterning, we believe that it is distinct from the previously reported patterns; our cases will contribute to a better understanding of pathogenesis of seborrheic keratosis.

Follow-up for patients with multiple seborrheic keratoses is important because malignant tumors can develop elsewhere on the body (or rarely within a seborrheic keratosis).[9] Treatment is usually not required unless the growths become irritated or are cosmetically displeasing. If treatment is needed, growths may be surgically removed or removed by cryotherapy (freezing).