p53 protein and proliferating cell nuclear antigen in eccrine poroma and porocarcinoma. an immunohistochemical study

Targeted molecular profiling reveals genetic heterogeneity of poromas and porocarcinomas

The genetic landscape of rare benign tumours and their malignant counterparts is still largely unexplored. While recent work showed that mutant HRAS is present in subsets of poromas and porocarcinomas, a more comprehensive genetic view on these rare adnexal neoplasms is lacking. Using high-coverage next generation sequencing, we investigated the mutational profile of 50 cancer-related genes in 12 cases (six poromas and six porocarcinomas). Non-synonymous mutations were found in two-thirds of both poromas and porocarcinomas. Hotspot HRAS mutations were identified in two poromas (p.G13R and p.Q61R) and one porocarcinoma (p.G13C). While in poromas only few cases showed single mutated genes, porocarcinomas showed greater genetic heterogeneity with up to six mutated genes per case. Recurrent TP53 mutations were found in all porocarcinomas that harboured mutated genes. Non-recurrent mutations in porocarcinomas were found in several additional tumour suppressors (RB1, APC, CDKN2A, and PTEN), and genes implicated in PI3K-AKT and MAPK signalling pathways (ABL1, PDGFRA, PIK3CA, HRAS, and RET). UV-associated mutations were found in TP53, APC, CDKN2A, PTEN, and RET. In conclusion, our study confirms and extends the spectrum of genetic lesions in poromas and porocarcinomas. While poromas exhibited only few mutations, which did not involve TP53, the majority of porocarcinomas harboured UV-mediated mutations in TP53 with some of these cases showing considerable genetic heterogeneity that may be clinically exploitable.

Porocarcinomas harbor recurrent HRAS-activating mutations and tumor suppressor inactivating mutations

Porocarcinomas are a rare eccrine carcinoma with significant metastatic potential. Oncogenic drivers of porocarcinomas have been underexplored, with PIK3CA-activating mutation reported in 1 case. We analyzed 5 porocarcinomas by next-generation sequencing using the DNA component of the Oncomine Comprehensive Assay, which provides data on copy number changes and mutational events in 126 cancer-relevant genes through multiplex polymerase chain reaction. We detected an average of 3.3 high-confidence nonsynonymous mutations per tumor (range, 1-6), including a spectrum of oncogenic activation and tumor suppressor inactivation events. Tumor suppressor mutations included TP53 (4/5, 80%), RB1 (3/5, 60%), ATM (2/5, 40%), ARID1A (1/5, 20%), and CDKN2A (1/5, 20%). In 4 (80%) of 5 tumors, at least 1 potential oncogenic driver was identified. Activating HRAS mutations were detected in 2 (40%) of 5, including G13D and Q61L hotspot mutations. Mutations of EGFR were identified in 2 (40%) of 5; these mutations have been previously reported in cancer but did not affect classic activation hotspot sites. EGFR and HRAS mutations were mutually exclusive. HRAS mutations were detected by targeted sequencing in a minority of benign eccrine poromas (2/17; 11.7%), suggesting that HRAS activation may rarely be an early event in sweat gland neoplasia. Together, our data suggest roles for HRAS and EGFR as drivers in a subset of poroma and porocarcinoma. TP53 and RB1 inactivation events are also likely to contribute to tumorigenesis. These findings suggest that porocarcinomas display diversity with respect to oncogenic drivers, which may have implications for targeted therapy in metastatic or unresectable cases.

Multiple eccrine poromas in the setting of total body irradiation and immunosuppression

Eccrine poromas are benign, adnexal tumors that most often occur as a solitary lesion on the palm or sole. The occurrence of multiple eccrine poromas is extremely rare. In this report, we describe the development of several eccrine poromas in an acral distribution in a 42-year-old man. Before the appearance of these tumors, the patient had received total body irradiation and allogeneic bone marrow transplantation for treatment of acute lymphocytic leukemia. As a complication of the bone marrow transplant, the patient developed chronic graft-versus-host disease, which was treated with immunosuppressive therapy. We discuss this patient and review the available literature regarding multiple eccrine poromas.

Malignant eccrine poroma in an unusual location

Malignant eccrine poroma is a rare skin appendage tumour, originating from the intraepidermal and upper dermal eccrine ducts. The tumour either arises spontaneously or develops in a long-standing eccrine poroma, generally in elderly people over 60. Clinically, it tends to be a localized lesion, which manifests itself as a nodule or ulcerated tumour, favouring extremities. We report an 83-year-old female with an enlarging and bleeding tumour on her lumbosacral region. This lesion first appeared as a small pigmented papule and progressed to an erythematous patch with central papular portion and some peripheral pigmentation. Histopathology revealed malignant eccrine poroma. Also, immunohistochemically, diffuse and intense p53 staining was observed. Regular pigment pattern, brown globules and black dots were seen in dermoscopic examination. After performing a wide excision, 20 months of follow-up revealed no recurrence or metastasis of the tumour. This case represents an unusually located malignant eccrine poroma with some pigmentation.

An assessment of the malignant potential of actinic keratoses and Bowen's disease: p53 and PCNA expression pattern correlate with the number of desmosomes

Actinic keratoses (AK) and Bowen's disease (BD), both intraepidermal skin tumors, have a potential progression to squamous cell carcinoma (SCC). To evaluate the malignant potential of AK and BD, the expression pattern of p53 protein and proliferating cell nuclear antigen (PCNA) were examined in five types of AK and BD by immunohistochemistry. The ultrastructural difference of epidermal cells between AK and BD lesions was investigated. In the study of p53 and PCNA expression, the atrophic and acantholytic types of AK showed lower positive rates compared to others. These two types did not demonstrate all layers expression pattern. The number of desmosomes of the epidermal cells was significantly reduced in BD, and in the bowenoid and hypertrophic types of AK compared with other types of AK The number of hemi-desmosomes showed greatest reduction in BD and the bowenoid type of AK On the basis of our findings, it is hypothesized that atrophic and acantholytic types of AK may have the lowest, and the bowenoid type of AK and BD may have the highest, malignant potential.

P53 Protein Expression in Eccrine Poroma and Porocarcinoma

The role of p53 mutation has been shown in different human malignancies, including various skin cancers. In this study, we examined p53 protein expression in 25 eccrine poromas and 11 porocarcinomas by immunohistochemistry. P53 expression was observed in 88% (22 of 25) of eccrine poromas and 73% (8 of 11) of porocarcinomas. In eccrine poromas, percentage of cells reactive for p53 was less than 5% (low expresser) in 6 cases, 5 to 50% (moderate expresser) in 14 and greater than 50% (high expresser) in 2 cases. In terms of intensity, 13 cases showed weak staining, 8 moderate, and 1 case showed strong reactivity. On the other hand, 2 cases of porocarcinoma were low expresser, 2 were moderate and 4 were high expresser. All of the high expressers had also strong staining. This study has demonstrated that eccrine poromas showed significant p53 expression as much as porocarcinomas and, therefore, p53 positivity cannot be accepted as a valuable parameter for malignancy. P53 gene may involve in the carcinogenetic pathway of porocarcinoma but it is likely that other oncogenes may also have a role.

Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases

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 review of tumor suppressor genes in cutaneous neoplasms with emphasis on cell cycle regulators

Cells normally have five options. These include renewal or proliferation, terminal differentiation, quiescence, senescence, and apoptosis. Many factors interact with cell cycle regulators to direct the cells toward these different options. Tumor suppressor genes play a pivotal role in this process. Alterations in these genes may limit the options that cells have and thus play a significant role in the multistep process of carcinogenesis. We will focus on tumor suppressor genes and especially tumor suppressor genes that interact directly with the cell cycle proteins.

Immunohistochemistry: a prognostic as well as diagnostic tool?

The assessment of proliferating cell populations has been used to aid in the differentiation of benign from malignant neoplasms, and it has been hoped that assessment of proliferation markers and oncogenic determinants holds information regarding prognosis. Various markers, including Ki-67, p53 protein, bcl-2, and proliferating cell nuclear or paraffin-embedded tissue. These determinants may prove useful in understanding the biology of certain neoplasms and may carry prognostic information that influences clinical management. Results in this developing field must always be interpreted in the clinical and histological context. This article reviews the applicability of some commonly available markers to selected skin disorders.