Eccrine Porocarcinoma (Malignant Eccrine Poroma)

Abstract

The clinicopathologic characteristics of 69 cases of eccrine porocarcinoma (EP) have been studied. Seven cases of purely in situ disease are included. Forty patients were female, 29 male with ages ranging from 29 to 91 years (mean 73 years). The lower extremity represented the single most common site (44%). Other common sites were the trunk (15 cases, 24%) and head (11 cases, 18%). The histologic diagnosis of EP was predicated on the basis of an irregular tumor at least partly formed of characteristic poromatous basaloid epithelial cells displaying ductal differentiation, and significant cytologic atypia. Forty-seven tumors (68%) contained mature well-formed eccrine ducts having an eosinophilic luminal cuticle, with the remaining tumors containing small ill-formed ducts and/or intracytoplasmic lumina. All ducts were discernible via light microscopy and in 49 cases were highlighted with DPAS stain and/or CEA/EMA immunocytochemistry. A variant with a broad pushing tumor margin and marked nuclear pleomorphism showed some resemblance to proliferative bowenoid dysplasia. In 11 cases (18%) the tumors appeared to arise in continuity with a benign preexistent poroma. A variety of histologic patterns were displayed including clear, squamous, and spindle cell differentiation, mucus cell metaplasia, and colonization by melanocytes. Lymphovascular invasion was present in 9 cases (15%). Three cases showed pagetoid extension of malignant cells (epidermotropism) and appeared to be multifocal. Follow-up was available in 54 patients (78%) with 9 (17%) experiencing local recurrence, 10 developing lymph node metastases (19%), and 6 (11%) experiencing distant metastases or death. Mitoses, the presence of lymphovascular invasion, and tumor depth >7 mm were associated with a poorer prognosis. Dividing tumors into those with a "pushing" or "infiltrating" advancing margin was also predictive of outcome with the latter having an increased risk of local recurrence. This report, the largest series of EP to date, suggests that the incidence of aggressive behavior is less than popularly believed. Furthermore, EP can display a wide variety of histologic patterns that may lead to diagnostic error in the unwary. The large number of cases in this series enables a reliable evaluation of prognostic parameters. A more aggressive clinical course may be indicated by more than 14 mitoses per high power field (hazard ratio [HR] for death 17.0, 95% confidence interval [CI] 2.71-107), lymphovascular invasion by tumor (HR 4.41, CI 1.13-17.2), and depth >7 mm (HR 5.49, CI 1.0-30.3). Thus, mitoses, lymphovascular invasion, and tumor depth should be evaluated in these tumors. We also suggest that tumors presenting an "infiltrative" advancing margin are particularly prone to local recurrence and require wide excision with close attention to the surgical margins by the reporting pathologist.

A Case of Recurrent Eccrine Porocarcinoma with Regional Lymph Nodal Metastasis, Arising on a Bowen’s Disease Patch

“…Mortality among patients with EPC with nodal metastasis is high at 67 % [3]. In their study of 69 patient cases, Robson et al [6] found that infiltrative as opposed to a pushing histologic subtype is predictive of local recurrence after controlling for both tumor depth and mitosis [6]. They also found that, depth >7 mm, >14 mitosis per high power field, and lymphovascular invasion were predictive of death due to EPC.…”

“…Most patients undergo surgical excision often with wide margin. But some of these patients go on to develop regional nodal involvement (20 %) or distant metastases (10 %) [6]. Mortality among patients with EPC with nodal metastasis is high at 67 % [3].…”

Porocarcinoma: relato de caso

“…9 In the case presented, the lesion was extensive, affecting the entire anterior thorax, a less common region, seen in 24% of the cases described in the literature. 10 The most affected locations, in 44% of cases, are the lower limbs, with 11% for the leg and 10% for the feet. 10 Other places less frequently described are the eyelids, penis and vulva.…”

“…10 The most affected locations, in 44% of cases, are the lower limbs, with 11% for the leg and 10% for the feet. 10 Other places less frequently described are the eyelids, penis and vulva. [11][12][13][14] It occurs with greater frequency in females and a 12-case study showed higher incidence in the age group with mean age of 70 years.…”

A Case of Clear Cell Eccrine Porocarcinoma

“…First described in 1963 by Pinkus and Mehregan as epidermotropic eccrine poroma 2 , the lesions of EP are clinically described as verrucous plaques or polypoid growths often mimicking squamous cell carcinoma or Bowen's disease. The lower extremities are the most commonly affected site, followed by the trunk and head 3 . The origin of the The tumor in this case should be distinguished from other tumors showing prominent clear cell changes, such as clear-cell Bowen's disease, sebaceous carcinoma, basal cell carcinoma with adnexal differentiation and balloon cell melanoma 6 .…”