Cystic fibroepithelioma of pinkus

Trichoblastic infundibular cyst should be renamed infundibular cyst with unique papillary projections

Trichoblastic infundibular cyst (TBIC) was previously reported as a unique keratinous cystic lesion, which was characterized by the papillary projections of follicular germinative-like cells emanating from the cyst wall. Here, we report three additional cases of this cyst and discuss the pathogenesis of this unique entity. In all cases, a unilocular cyst contained keratin, and the cyst wall was composed of squamous epithelium. A number of cords and papillary projections emanated from the basal layer of the cyst wall. They were composed of cells with large nuclei and scant cytoplasm arranged in a peripheral palisade. Immunohistochemically, anti-cytokeratin 15, anti-cytokeratin 20, and anti-epithelial cell adhesion molecule antibodies were negative. Thus, these cells resembled follicular germinative cells or sebaceous mantle morphologically, but we failed to prove the differentiation immunohistochemically. The cyst was surrounded by fibrotic stroma and inflammatory cells, suggesting previous rupture of the cyst. We speculate that the cells of the projections possibly differentiate into the mantle rather than follicular germinative cells, even though we could not provide sufficient immunohistochemical evidence. We also suggest that they may be induced by special reaction to fibrohistiocytic stroma surrounding the infundibular cyst. Therefore, TBIC should be renamed infundibular cyst with unique papillary projections.

Fibroepithelioma of Pinkus (FeP) Located in the Left Lower Quadrant of the Abdomen - Case Report and Review of the Literature

BACKGROUND

Fibroepithelioma of Pinkus (FeP) is an uncommon and controversial skin lesion, sharing features of both basal cell carcinoma (BCC) and trichoepithelioma. In this article, we present a case of FeP and synthesise current concepts on the etiopathogenesis, diagnosis and treatment of this uncommon tumour.

CASE REPORT

We report the case of an 88-year-old male patient presenting to the dermatology clinic for a sharply demarcated, pink, exophytic cutaneous tumour situated in the left inguinal region. The histopathological examination performed after complete surgical excision of the lesion revealed a diagnosis of FeP. A systematic review of the literature was conducted. The terms `fibroepithelioma` and `Pinkus` have been searched in bibliographical databases, including PubMed and Google Scholar, without time limitation up to February 15th, 2017. Seventy-nine articles that fulfilled all the required conditions were identified. Relevant citations and additional articles identified from references have been assessed. The systematic review included a total number of 452 cases of FeP.

CONCLUSION

Even though FeP is considered a relatively rare tumour, its true incidence rate might be higher than previously believed. The clinical aspects of the lesion described in this paper and its location in the left lower quadrant of the abdomen are classic features of FeP. Histopathologic examination revealed features of both BCC and trichoepithelioma. Further epidemiological studies are required to clarify whether patients with FEP should be screened for the occurrence of other malignancies.

Fibroepithelioma of Pinkus Revisited

Background

Fibroepithelioma of Pinkus (FeP) is considered a variant of basal cell carcinoma (BCC); however, in the past 20 years, some researchers have argued for its classification as a trichoblastoma. Recently, use of a new immunostaining marker and further dermoscopic characterization of FeP have advanced the debate about its proper classification.

Purpose

A review of the evidence for and against classification of FeP as BCC or trichoblastoma is presented.

Methods

Using PubMed, the term FeP was searched and relevant citations were assessed. Additional relevant articles were identified from references of key papers.

Results

FeP shares characteristics of both trichoblastoma and BCC.

Conclusion

Derived from the same cell type, BCC and trichoblastoma may be best considered as representing opposite ends of a spectrum of differentiation, with FeP deserving an intermediate classification.

Cystic fibroepithelioma of Pinkus: two new cases and cystic changes in classical fibroepithelioma of Pinkus

We report two new cases of cystic fibroepithelioma of Pinkus together with immunohistochemical features and analyze the presence of cystic changes in a series of 16 classical fibroepitheliomas of Pinkus. Our findings show that the formation of cystic spaces is most probably caused by ischemic degeneration of stromal fenestrations, rather than by central tumor cell necrosis. This finding is supported by lack of CD34 positive blood vessels in edematous and hyalinized stromal fenestrations undergoing transformation into cystic spaces, as opposed to the uninvolved stromal fenestrations. Therefore, it is probably more accurate to refer to this process as pseudocystic stromal degeneration rather than true cyst formation. Also, two out of 16 classical Pinkus fibroepitheliomas exhibited focal pseudocystic changes in 50% and 10% of the tumor, respectively, demonstrating that this degenerative process can be found, rarely and focally, in classical cases as well.

Fibroepithelioma of pinkus on mucocutaneous junction

Fibroepithelioma of Pinkus is a variant form of basal cell carcinoma that clinically presents as a single or multiple red plaques or flesh-colored nodules without ulceration. It is usually located in the trunk, inguinal, or crural areas and only rarely occurs on the mucocutaneous junction. A 57-year-old male patient presented with a mass at the left nostril, which had first appeared about 10 years earlier. A single nontender red lesion was about 1 cm in size, and its base was on the mucocutaneous junction at the floor of the left nostril. The patient did not complain of any pain. Computed tomography results revealed a 0.8 × 0.8 × 1.0-cm mass with moderate enhancement at the left nostril without infiltration to the adjacent soft tissue. Wide local excision was carried out with an adequate resection margin under local anesthesia. Microscopic examination showed strands of basaloid cells infiltrating into the stroma, forming an interanastomosing pattern. The specimen exhibited no atypia, and the margin of excised mass was clear. The patient is being monitored for any possible local recurrence.

Basal cell carcinoma: biology, morphology and clinical implications

Basal cell carcinoma (BCC) is the most common malignant neoplasm of humans. Rising dramatically in incidence in North America, as likely reflects changing habits of the population and a move from more northerly climes to the sunbelt of the Southern and Southwestern United States, the incidence is surely to rise even higher in the future. The last decade has seen significant advances in our understanding of BCC biology and novel approaches to therapy, which hinge upon accurate diagnosis and subclassification by pathologists. The purpose of this review article is to summate the research advances in our understanding of BCC biology and to acquaint pathologists and clinicians to the practical issues in BCC diagnosis and subclassification which flow there from.

Fibroepithelioma of Pinkus Is a Fenestrated Trichoblastoma

Pinkus described "pre-malignant fibroepithelioma" as a proliferation that gave rise to many tiny basal cell carcinomas within each lesion. Later authors have generally considered it to be an unusual variant of basal cell carcinoma (BCC). The delineation of trichoblastoma as the general term for the benign counterpart of BCC raises the possibility that the fibroepithelioma of Pinkus (FEP) would be better classified under that rubric. To address this subject, we examined the records of 114 patients with FEP for body site, age and sex distribution, and sections from 75 lesions. All FEP examined show a blunt interface with the underlying dermis (where one could be seen), differentiation toward follicular bulbs and papillae, and large areas of cellular stroma. FEP has a slight female preponderance in contrast to BCC, which is more common in males. Unlike the common types of BCC, FEP has an overwhelming predilection for the trunk and extremities, and only 5% of tumors are set in a dermis with significant amounts of solar elastosis. Next, FEP, BCC, and FEP with BCC-like areas were stained with MIB-1 (to assess proliferation), p53 (an oncogene product), and CK20 (a Merkel cell marker) antisera. FEP shows a low level of staining for p53 and MIB-1, in contrast to conventional BCCs that over-express these markers. FEP also shows retention of Merkel cells, a characteristic of benign neoplasms with follicular germinative differentiation but not in general of BCC. The BCC-like areas in some FEP tumors reflect these staining tendencies with less striking differences. Given the contrast between FEP and BCC with respect to site of occurrence, relationship to sun damage, histopathologic features, and immunohistochemical studies, it appears that FEP more closely resembles trichoblastoma than BCC.

Pedunculated basal cell epithelioma which is not Pinkus tumor

A 33-year-old female with pedunculated basal cell epithelioma was reported. She had noticed a cutaneous tumor on the scalp for two years before admission. It developed gradually and clinically resembled fibroma or pigmented nevus. Total resection was performed, and its histopathology revealed the solid or cystic type of basal cell epithelioma.