EPC is an infrequent cutaneous neoplasm arising from the cells of the acrosyringium with metastatic potential. This tumor may occur de novo or developing from a pre-existing lesion as degenerative progression, and it can manifest clinically as a solitary lesion with non characteristic macroscopic appearance, as an ulcerated nodule or as a plaque, polypoid, or verrucous lesion [
14]. The most common location of EPC are the lower limbs, head and neck, trunk, vulva, breast, nail bed and upper extremities [
15]. The histological diagnosis can be done on specific microscopic features. In the primary tumor, the malignant cells arise from the intraepidermal portion of the eccrine sweat glands and may be limited to the epidermis or may extend into the dermis. The tumor are asymmetric with cords and lobules of polygonal tumor cell, typically with a cribriform pattern. Nuclear atypia is evident, with frequent mitoses and necrosis. From the lymphatics, the tumor cells can invade the overlying epidermis because of the "epidermotropic" nature of the tumor cells (Pagetoid pattern) [
16‐
18]. Immunohistochemical studies with positive staining using antibodies to various kinds of antigens (human CK, EMA, carcynoembrionic antigen, p53 protein and others) can be done to confirm acrosyringeal differentiation and to support the conclusive diagnosis [
9]. The differential diagnosis of EPC is extensive and runs the spectrum of basal cell carcinoma to metastatic adenocarcinoma [
15]. Histologic findings predictive of the aggressive clinical course were the evidence of lymphovascular invasion, which is associated with multiple regional cutaneous metastases, the existence of more than 14 mitoses per field and a tumoral depth of more than 7 mm [
5]. In our case, the tumor depth was 3.3 mm with mitotic activity of 14 mitoses per 10 high-power fields, and it showed lymphovascular invasion and Pagetoid intraepidermal extension. Both regional and distant metastases are attributed to the tumor's ability to invade the dermal lymphatics. Solid organ metastases are observed in 10% of cases, lymph nodes metastases in 20% of cases, and local recurrence in 20% of cases [
5‐
15]. However the prognosis of this carcinoma seems difficult to establish due to missed follow-up of cases described in the literature and tumor rarity.
The optimum surgical treatment for EPC is wide surgical excision of the primary tumor with broad tumor margins, given the propensity for local recurrences, with curative rates from 70% to 80% of cases [
14‐
18]. Therapeutic lymphadenectomy should be performed in case of lymphadenopathy, while the role of sentinel lymph node biopsy (SLNB) for staging EPC remains unknown, and probably may be reserved in cases of histological aggressiveness or intralymphatic permeation by the primary tumor [
16‐
20]. In our case, tumor cells were detected in the needle aspiration of the left axillary lymph node and an axillary lymphadenectomy was performed.
Electroporation, which can be used to introduce chemotherapeutic drugs directly into cancer cells (electrochemotherapy), has been shown in clinical trials to have a high response rate in treatment of patients with primary or metastatic skin cancers. The procedure is normally well tolerated by patients and can be repeated [
21]. It should be considered as an excellent alternative to standard therapies in treatment of locoregional recurrent EPC.
No standard therapeutic protocols for metastatic EPC exist. However, a variety of chemotherapeutics have been used with varying degree of responsiveness. Gonzales-Lopez et al reported a case of a 71-year-old man developing multiple cutaneous and regional lymph node metastases 15 months after surgical excision of the primary tumor, treated with lymphadenectomy, radiotherapy, and oral isotretinoin, subsequently substituted by tegafur, with no evidence of distant metastases after a 5.6-year follow-up [
16].