A serpentine inside eccrine spiradenoma: a new trichoscopic sign.

Trichoscopy being an in vivo technique aids in magnification of cutaneous structures with appropriate pattern and color. A female presented with erythematous tumor on scalp. Histopathology showed features of eccrine spiradenoma. Authors evaluated trichoscopic patterns in eccrine spiradenoma. It demonstrated specific trichoscopic pattern in the form of linear red structure appearing as 'serpentine'. Authors believe that this new trichoscopic pattern is hallmark of eccrine spiradenoma and can be utilized in the diagnosis.

INTRODUCTION

Eccrine spiradenoma (ES) also called as spiradenoma, is a benign tumor of sweat gland origin and is distinguished by its histology. It usually occurs as a solitary, firm, rounded, gray-pink dermal nodule.[1]

Commonly it measures <1 cm. There are many variants described in the literature. Pain and tenderness are frequently present.[2] It can occur along with cylindromas.[3] Lesions with features of spiradenoma may be part of the Brooke-Spiegler syndrome.[4] It demonstrates definite histopathology and hence it is the gold standard in the diagnosis.[2] Authors evaluated trichoscopy of ES and specific patterns of trichoscopy are helpful in the diagnosis of ES.

CASE REPORT

A 22-year-old female presented to the outpatient department of dermatology with skin lesion on the scalp for 3 months. On examination, pink nodule was situated on the occipital area [Figure 1]. It was firm in consistency and was 0.5 cm × 0.5 cm in measurement. It used to bleed on manipulation. No history of trauma to the site. There was no significant medical history. Systemic examination was unremarkable. Blood and urinalysis were within normal limits. Trichoscopy was performed using DermLite 3 polarized dermoscopy. It demonstrated reddish linear structure traversing the entire lesion, and it appeared like a serpentine. The reddish structure was surrounded by whitish areas [Figure 2]. Histopathology of the lesion revealed lobules in the tumor with two types of cells. One type cells were situated at the periphery with dark nuclei and the second type cells were present in the center. Blood vessels were dilated. There was increased collagen in dermis [Figures 3 and 4].

Figure 1

Clinical image of eccrine spiradenoma presenting as erythematous nodule on the scalp

Figure 2

Trichoscopy of eccrine spiradenoma showing “serpentine-like” linear reddish structure (yellow arrow) surrounded by whitish areas (black arrows)

Figure 3

Histopathology showing tumor lobules (black arrow) and dilated blood vessels (yellow arrows) in the dermis (H and E, ×4)

Figure 4

Histopathology showing large, pale tumor cells in the center and small, dark cells at the periphery arranged in cards (H and E, ×40)

DISCUSSION

Eccrine spiradenoma is a benign tumor of eccrine sweat gland. Diagnosis is made due to its characteristic features such as firm, dome-shaped dark blue tumor. However, it is difficult to differentiate from pyogenic granuloma and other dermal tumors.[1] Pyogenic granuloma presents as a solitary, rapidly growing, papule or polyp that bleeds easily after minor trauma.[5]

Dermoscopy is a simple, noninvasive diagnostic tool, which magnifies surface and subsurface structures, which can aid in clinical diagnosis.[6]

Trichoscopy, the dermoscopy of hair and scalp, demonstrates characteristic patterns in many dermal tumors namely pyogenic granuloma,[5] dermatofibroma and clear cell acanthoma.[7] Trichoscopy of pyogenic granuloma shows “reddish homogeneous area” and “white rail lines” histologically corresponding to numerous proliferating vessels and the fibrous septa respectively.[8]

Red globules or structures observed under dermoscopy correspond to dilated capillaries in the dermis.[9] Hence, they play a vital role in differentiation of many conditions. In psoriasis, they are observed as regularly dotted vessels over a light-red background. They take patchy configuration on a yellow background in pityriasis rosea. And, in classical lichen planus, vessels are arranged peripherally in the confines of white crossing lines, and they appear as clear red globules.[9] They appear as “hairpin-like” in seborrheic keratosis, as arborizing vessels in basal cell carcinoma and as “string of pearls vessels” in clear cell acanthoma.[7]

Histopathology of ES shows lobules with two cell types in the islands. Larger, pale cells are grouped around lumina and smaller dark cells situated at the periphery. Small, tubular structures or cystic spaces may be observed.[10]

The lobules consist of large, thin-walled, dilated vascular channels, and these lobules are surrounded by condensed connective tissue, which may encroach on the islands as hyaline droplets.[11]

In this case study of ES, red globules in a linear fashion appeared as “serpentine” under trichoscopy corresponding to dilated blood vessels. Whitish areas surrounding red globules correspond to condensed connective tissue in the dermis. Trichoscopy of ES is not reported in the literature.

CONCLUSION

Eccrine spiradenoma demonstrates red linear strand in “serpentine” pattern. Authors believe that this trichoscopic pattern is the hallmark of ES and propose that this new trichoscopic can be utilized in the diagnosis of ES. To the best of our knowledge, this is first report of trichoscopic pattern of ES from Indian sub-continent. However, further studies involving large sample size are recommended.