Eccrine Porocarcinoma: Clinical and Histopathological Study of 14 Patients with Special Emphasis on Sentinel Lymph Node Biopsy.

Eccrine porocarcinoma is a rare skin adnexal tumour that affects elderly people. Most eccrine porocarcinomas are stage I or II according to the American Joint Committee on Cancer. The prognosis is good in early stages, but worsens when advanced. Since information on the use of sentinel lymph node biopsy in these patients is scarce, this study examined the records of all patients with eccrine porocarcinoma treated at Helsinki University Hospital during a 17-year period and focused on sentinel lymph node biopsy patients. The study identified 14 patients (9 male, 5 female). There were 2 metastases to the lymph nodes and 2 recurrences at initial referral to our institution. All primary tumours had wide local excision and 6 patients also had sentinel lymph node biopsy, of whom none had positive lymph nodes. There were no new metastases or recurrences during follow-up. Three patients died of causes other than eccrine porocarcinoma. When comparing the wide local excision only and wide local excision with sentinel lymph node biopsy groups, no parameters reached statistical significance. The decision process of the multidisciplinary tumour board meeting on whether to perform sentinel lymph node biopsy was not clear, perhaps due to the limited knowledge of eccrine porocarcinoma. Further studies and international collaboration are warranted.

Merkel cell polyomavirus is a passenger virus in both poroma and porocarcinoma.

BACKGROUND: Merkel cell polyomavirus (MCPyV) has been studied in several malignant and nonmalignant tissues. However, only in Merkel cell carcinoma (MCC) has the connection to tumorigenesis been established. Previously, eccrine porocarcinoma samples were shown to express MCPyV in the majority of samples. We aimed to examine MCPyV in porocarcinoma and poroma samples using MCC as the reference material. METHODS: We analyzed 17 porocarcinoma and 50 poroma samples for the presence of MCPyV using LT antigen immunostaining and DNA detection methods. In addition, 180 MCC samples served as controls. RESULTS: MCPyV LT antigen immunostaining was detected in 10% of poroma and 18% of porocarcinoma samples; on the other hand, it was present in 65% of MCC samples. MCPyV DNA was detected in only 10% of poroma and porocarcinoma samples compared with 96% of MCC samples. The viral DNA copy number in all MCPyV DNA-positive MCCs was at least 25 times higher than that in porocarcinoma or poroma samples with the highest MCPyV DNA-to-PTPRG ratio. CONCLUSIONS: The low number of viral DNA copies in poroma and porocarcinoma samples, together with the negative LT expression of MCPyV DNA-positive tumors, indicates that MCPyV is simply a passenger virus rather than an oncogenic driver of porocarcinoma.

Malignant Eccrine Porocarcinoma in Finland During 2007 to 2017.

Malignant eccrine porocarcinoma is a rare skin adnexal cancer arising from the sweat glands. Little is known about the epidemiology and incidence of eccrine porocarcinoma. This registry-based study examined the epidemiology and incidence data for eccrine porocarcinoma from the Finnish Cancer Registry. The study included all persons diagnosed with eccrine porocarcinoma in 2007 to 2017. There were 69 cases in the study period; 34 (49%) male and 35 (51%) female patients. Mean age at diagnosis was 75.5 years. Incidence for men was 0.06 per 100,000 person-years and for women 0.04 per 100,000 person-years adjusted for age according to the World Standard Population. Incidence increased with age. There was one eccrine porocarcinoma-specific death among the 69 patients. The incidence of eccrine porocarcinoma in Finland is therefore low. The mean age at time of diagnosis and the location of eccrine porocarcinoma are consistent with previous reports. The survival of patients with eccrine porocarcinoma is high.