gms | German Medical Science

Eccrine spiradenoma is a rare benign skin tumour [1]. It was first described in 1956 by Kersting and Herwig who established that the lesion is of sweat gland origin [1], [2], [3]. Eccrine spiradenoma often presents as a slow growing, encapsulated cystic, non-tender, nodular swelling on the trunk and in the extremities [2], [4]. Multiple lesions and those presenting on the scalp are rare [1], [5]. Given its rarity, well-defined treatment guidelines have not yet been established. However, most studies recommend surgical excision as the gold-standard treatment [1], [6]. Using collective evidence, our review aims to summarise all reported cases of solitary scalp eccrine spiradenomas; their clinical presentation, histopathological features and management.

A 50-year-old male presented with a solitary cystic lesion of the scalp with no associated symptoms. He was a non-smoker, with no personal or family history of cutaneous tumours.

On examination, the lesion was a 26 mm x 24 mm non-pigmented nodular lesion with a smooth surface and regular border (c.f. Figure 1 [Fig. 1]). No lymphadenopathy of the head and neck was appreciated. The lesion was fully excised under local anaesthesia, with primary closure and no visible scalp defect. Histopathological analysis revealed a cutaneous tissue incorporating a benign adnexal neoplasm with a multilobar architecture and occasional foci of cyst formation. The patient had no recurrence nor were any postoperative complications detected on subsequent visits to our plastic dressing clinic.

A MEDLINE, PubMed and Cochrane Library search was carried out for between January 1999 and January 2019 using a combination of terms (child, adult) and keywords (eccrine spiradenoma, eccrine adenoma, sweat gland tumour, scalp, head).

• Inclusion criteria: systematic review, randomised controlled trials, review articles, cohort studies and case reports
• Exclusion criteria: laboratory studies and non-English translated articles

The literature review was independently repeated by two authors. Six studies met our inclusion criteria. Three articles were excluded as they were reported as multiple eccrine spiradenomas (Figure 2 [Fig. 2]).

Including our case report, of the 4 papers that were included in the final review, there were 2 females and 2 male patients with a mean age at excision of 36 years (range: 15–55 years)

There was a bimodal distribution, with most lesions occurring in the first 3 decades (50%) and in the 6^th decade (50%) (Figure 3 [Fig. 3]). Information about ethnicity was available in all studies: 2 Caucasians, 1 Chinese and 1 Indian (Table 1 [Tab. 1], Table 2 [Tab. 2]).

Our patient had been investigated for Brooke-Spiegler’s syndrome. In the remaining 3 papers, there was no patient with an associated genetic condition.

Most patients presented with an asymptomatic cystic nodule. Two patients presented with lesions over the occipital region and in 1 patient the lesion was over the right temporal region. All 4 patients presented due to aesthetic reasons. Pain was not an indication for presentation. Lesions ranged from 5 mm to 15 mm in diameter, with a mean size of 19 mm (range in mm: 12–26) and 10 mm (range in mm: 5–15) in males and females, respectively. This translates to a total mean size of approximately 15 mm across all cases.

Excised lesions were all investigated using haematoxylin and eosin (H and E) staining. The histology findings from all 4 patients revealed a common pattern of two types of distinctive cell types:

1.

central basaloid or cuboidal cells;

2.

peripheral small cells containing dark nuclei and pale cytoplasm (Figure 4 [Fig. 4]).

Individual papers commented on other features such as the presence of hair follicles, cells devoid of atypia or significant mitotic activity [7]. Using a dermoscope, Ankad et al. demonstrated a new specific trichoscopic pattern of eccrine spiradenoma, in the form of a linear red structure appearing as a ‘serpentine’ [8].

In the 4 studies, patients underwent complete excision of the lesion with uncomplicated outcomes. There were no recurrences or malignancies reported on subsequent follow-ups. The length of follow-up was not documented in any of the 3 papers, excluding our case.

It is reported that the age distribution of eccrine spiradenomas is bimodal with most lesions occurring in the first three decades and in the sixth decade [9]. Our review demonstrated similar findings with the mean age during lesion excision being 36 years (range 15 to 55 years) [1], [10]. Considering the distribution of gender, previous reviews reported an equal male to female ratio [2], [6]. Our review suggested similar results. We found an equal percentage number of Caucasians and Asians. Though, this may be a misrepresentation of the exact ethnic distribution as patients from less-developed countries may not present to clinic.

The manifestation of eccrine spiradenoma de novo is known to be due to the presence of faulty tumour suppressor genes, supporting the degenerative progressive tumour theory [4], [9]. For instance, in conditions such as Brooke-Spiegler syndrome, of which eccrine spiradenoma is a cutaneous feature, faulty genes have been found such as the CYLD gene on chromosome 9 [6], [7], [9], [11]. This further supports the fact that cells of eccrine spiradenoma also display apocrine and trichoepitheliomatous differentiation [9], [12]. This may suggest that eccrine spiradenoma are in fact of mixed eccrine, follicular and apocrine descent [9], [13].

Based on immunohistochemistry and stem cell studies, it is plausible that initiating mutations in proto-oncogenes and/or tumour suppressor may lead to formation of malignant eccrine spiradenomas, albeit this being a small transformation risk [14], [15]. In such rare cases of malignant transformation, an increased expression of the p53 gene is also observed and is a useful marker if the malignancy status is unknown [9], [16].

To our knowledge, our case report is the first documented in the United Kingdom of pure solitary eccrine spiradenoma of the scalp. Typically, it presents as a pink or blue, solitary, nodulo-cystic, smooth lesion [9], [17], [18]. Few studies have however reported multiple lesions on the scalp [9], [12]. In our review, all four patients presented because of aesthetic concerns about the lesion. In the literature, eccrine spiradenomas on extremities have been associated with pain [6], [9]. Scalp eccrine spiradenoma may differ in its presentation, in that it is less commonly associated with pain [10]. Thus, scalp eccrine spiradenomas presenting with symptoms such as pain and bleeding are rare, and should raise suspicion of locoregional disease. Metastases to distant sites have been reported in some cases, often to regional lymph nodes and rarely to bone [19], [20]. Malignant change is characterised by rapid enlargement of a cutaneous nodule, increasing tenderness and ulceration [1], [21]. In our review, only one paper recorded the time from diagnosis to excision, and so it is difficult to identify the exact benign-malignancy time-length. What we know is that, at presentation, 40% of those with malignant eccrine spiradenoma have metastases, suggesting an aggressive nature of its malignant form [22], [23]. Thus, we recommend excision of the lesion as soon as a clinical diagnosis of eccrine spiradenoma has been established.

The histological and clinical distinctions between benign eccrine spiradenomas and other benign skin tumours such as angioleiomyoma and glomus tumours can be challenging due to their cytological constituents and similar presentation. Lack of specific immunohistochemical markers to differentiate them is also a contributing factor [6], [24]. In this regard, the presence of peripheral small, dark basaloid cells and central large pale cells, with acidophilic nuclei, were the commonest pathological findings.

The role of dermoscopy to identify a trichoscopic pattern of eccrine spiradenoma, in the form of a linear red structure appearing as a ‘serpentine’, appears to be a new and useful clinical distinguishing factor [8]. Further to this, eccrine spiradenomas express markers such as cluster of differentiation (CD) 200 gene, S-100 protein, carcinoembryonic antigen (CEA) and cytokeratin. Angioleiomyoma typically express smooth muscle actin (SMA) and glomus tumours are usually associated with conspicuous vasculature components [4], [6], [25].

As a result of the rarity of scalp eccrine spiradenomas, there are no agreed standards for their management. Complete surgical excision is the recommended first line [5], [6]. Radiotherapy and chemotherapy may be more suited to the treatment of recurrent disease or residual macroscopic disease [6], [26]. One of the papers in our review mentioned a 2 mm excision margin, and it appears that if eccrine spiradenoma of the scalp is fully excised, with an adequate safety margin, there is no recurrence [27], [28]. Indeed, none of the patients in our review had any disease recurrence following excision.

Eccrine spiradenomas of the scalp are tumours originating from sweat gland. Current literature suggests they may also develop from hair follicles and apocrine cells.

Mutations in the p53 and CYLD genes have been mentioned to be thought of as implicated in development of eccrine spiradenomas [9], [16]. The tricoscopic serpentine pattern appears to be a useful clinical diagnostic sign [8], [29]. Complete surgical excision is almost always curative.

The authors declare that they have no competing interests.

The copyright holder of Fig. 1 is the Korean Cleft Palate-Craniofacial Association and Fig. 1 is distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), whereas the article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).