Dermoscopy of Eruptive Syringoma

Abstract

Syringoma is a benign adnexal tumor of eccrine origin. Eruptive syringoma (ES) is a rare variant and can mimic other diseases especially lichen planus (LP). The dermoscopic observation of ES is not well described. We report here a case of ES, initially misdiagnosed as LP. The dermoscopic findings showed fine reticulate brown lines on a light brown background contrarily to the findings usually seen in LP. These findings prompt a skin biopsy which subsequently confirmed the diagnosis of ES. The use of dermoscopy in ES can be useful and may help differentiate it from other diseases.

Established Facts

• Syringoma is a benign adnexal tumor of eccrine origin and has a variety of clinical presentations.

• Eruptive syringoma is a rare variant and can mimic other diseases clinically especially lichen planus.

Novel Insights

• The dermoscopic features of eruptive syringoma in our patient showed fine reticulate brown lines on a light brown background which can be useful and may help differentiate it from other diseases.

Introduction

Syringoma is a benign adnexal tumor derived from the ducts of eccrine sweat glands [1]. It typically affects young to middle-aged females, predominately in the periorbital region [2]. Eruptive syringoma (ES) is a rare variant of generalized syringoma and can mimic other diseases clinically. Dermoscopy can be a useful tool in such cases. The dermoscopic observation of ES is not well described. We report here a case of ES to demonstrate its dermoscopic features.

Case Report/Case Presentation

An otherwise healthy 36-year-old woman presented with itchy skin lesions for more than a year. None of her family members had similar lesions. On examination, there were multiple brown and skin-colored flat-topped papules over anterior trunk (Fig. 1). Dermoscopy showed fine reticulate brown lines on a light brown background (Fig. 1). Histopathology findings showed a circumscribed proliferation of small and large ducts in the superficial dermis, larger ducts were dilated and filled with secretion, while smaller ones showed comma-shaped extensions “tad pole pattern” embedded in a fibrous stroma in the upper dermis and presence of melanin in the rete ridges (Fig. 2). The diagnosis of ES was established and no treatment was initiated. The lesions remained stable with no progression.

Fig. 1.

Multiple brown flat-topped papules on the left lower abdomen (left). Dermoscopy shows fine reticulate brown lines on a light brown background (right) (DermLite DL4, polarized mode, magnification ×10).

Fig. 2.

A circumscribed proliferation of small and large ducts embedded in a fibrotic stroma. Hyperpigmented rete ridges are noted (magnification ×10).

Discussion/Conclusion

Syringoma is a harmless benign adnexal neoplasm of eccrine origin. It can appear at any age but usually occur after puberty [2]. Women are more frequently affected than men [1]. Syringoma has a variety of clinical presentations including localized and generalized forms as well as familial types and in association with Down's syndrome [3]. Other rare forms as plaque-type, linear, and milium-like syringoma have been reported [2]. In localized forms, it typically involves the periorbital region and the diagnosis is made clinically [4]. However, in ES, the neck, anterior trunk, and axilla are the most frequently involved sites [2]. Lesions are usually symmetrical and characterized by asymptomatic or pruritic skin-colored to brownish shiny papules [5]. The pathophysiology of ES is not fully understood. It has been proposed that a previous cutaneous inflammatory process may lead to hyperplastic reactive process in eccrine duct resulting in the development of ES [5].

ES may be confused with other diseases such as lichen planus (LP), mastocytosis, or histiocytosis. Of note, our patient was misdiagnosed and treated for LP by previous dermatologists. The use of dermoscopy may help differentiate ES from other diseases. There are limited data describing the dermoscopic features of syringoma (Table 1). An image of homogeneous brownish area with delicate brown pigment network was reported for linear syringoma [1] and shiny white structures over a fading pink background with dotted and linear vessels were seen in vulvar syringoma [6]. Dermoscopic findings of incomplete pigment network with a reddish tinge were described in a patient with ES [3]. In recent report with 2 cases of ES, features of reticular light brown lines, structureless light brown areas, and reticular vessels were seen on dermoscopy [4], as shown in our patient. It is suggested that fibrotic stroma in syringoma might cause epidermal thickening and basal melanosis, as often shown in derma­tofibroma [1] and that the pigment network seen in dermoscopy correlates to the presence of melanin in basal layer. Of note, dermoscopic features of LP usually show white reticulate lines corresponding to Wickham's striae [4] and thus can be differentiated from ES. The definite diagnosis of ES can be made on histopathological examination as it includes distinct features including the characteristic comma shaped tail “tad pole pattern” comprised of dilated cystic eccrine ducts [7]. Treatment of syringoma is unsatisfactory [5, 7, 8] and often includes physical modalities as excision, cryotherapy, electrodessication, or laser therapy. Topical and oral retinoids have been used in generalized forms with little improvement [8].

Table 1.

Review of previously reported dermoscopic features of syringoma in literature

Author	Patients, n	Syringoma type	Clinical features	Dermoscopic findings
Hayashi et al. [1]	1	Linear type	Linear dusky erythematous macules over the left arm	Homogenous brownish area and delicate pigment network
Sakiyama et al. [3]	2	Eruptive type	Multiple skin-colored to light red papules in intertriginous areas	Pigment network with a reddish tinge
Corazza et al. [6]	1	Vulvar type	Single pink-yellowish papule of the vulva	Glittering yellow-whitish round structures with dotted and short linear vessels
Botsali et al. [4]	2	Eruptive type	Multiple red to brown macules and papules on the trunk and intertriginous areas	Reticular light brown network and light brown areas with reticular vessels

Dermoscopy is considered as a helpful tool in the diagnosis of pigmented lesions [1]. However, it is also useful when evaluating other lesions, as in our case. The diagnosis of ES can be easily missed and the use of dermoscopy can differentiate ES from LP and helps narrow the differential diagnosis.

Statement of Ethics

A written consent was obtained from the patient to publish photos and details of the case.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

The authors did not receive any funding.

Author Contributions

Aleissa wrote the manuscript, performed clinical and dermoscopic examinations, and did the literature research. Aljarbou did the histopathology examination and revised and commented on the manuscript. Aljasser performed clinical and dermoscopic examinations and revised and commented on the manuscript.