Eccrine porocarcinoma of the thumb in a patient with chronic exposure to benzene glue.

Eccrine porocarcinoma (EPC) is an uncommon and aggressive type of skin cancer that originates from the intraepidermal component of the sweat gland apparatus, also known as acrosyringium [1]. The first case was reported in 1963 by Pinkus and Mehregan. The authors referred to this tumour as “epidermotropic eccrine carcinoma” [2], whereas Mishma and Moriok in 1969, were the first ones to coin the term “eccrine porocarcinoma” [3] and focused on the common histopathologic transformation of the benign form of eccrine poroma to its subsequent malignant counterpart. This type of skin cancer is extremely rare and corresponds to 0.005 to 0.01 % of all the cutaneous tumors [4]. According to data from the Rare Care-Surveillance of Rare Cancers in Europe, the incidence rate is 0.28/100.000 for the skin adnexal carcinoma of the skin [5]. EPC occurs in both sexes and has been described to have a female predominance and it is often seen during the 6th to 8th decades of life [6],[7]. It can occur de-novo or on a pre-existing eccrine poroma lesion. It arises mainly in the lower limbs, head, trunk and hands [6]. No standard treatment has yet been established. Wide excision and Mohs surgery have been described as treatment options with chemotherapy to be the only management modality for lymph node spread of the tumor. Even by wide local excision with tumour-free margins, about 20 % of EPC will recur and 20 % will present regional nodal metastases [8]. Distant metastases are rare, although have been reported by Robson et al. [6]. Eccrine porocarcinoma should be differentiated from aggressive digital papillary adenocarcinoma, an extremely rare type of sweat gland carcinoma that is essentially limited to the digits [9] but has a much more aggressive behaviour, with a high rate of local recurrences and distant metastases [10].