Expression of Androgen Receptor by Fibroepithelioma of Pinkus: Evidence Supporting Classification as a Basal Cell Carcinoma Variant?

Cutaneous Lymphadenoma Is a Distinct Trichoblastoma-like Lymphoepithelial Tumor With Diffuse Androgen Receptor Immunoreactivity, Notch1 Ligand in Reed-Sternberg-like Cells, and Common EGFR Somatic Mutations

The term "cutaneous lymphadenoma" was coined in this journal for an unusual lymphoepithelial cutaneous adnexal neoplasm, possibly with immature pilosebaceous differentiation. Some authors further proposed that cutaneous lymphadenoma was an adamantinoid trichoblastoma. However, although a hair follicle differentiation is widely accepted, the fact that this is a lymphoepithelial tumor is not appropriately explained by the trichoblastoma hypothesis. Our goal was to further clarify the phenotypic and genotypic features of cutaneous lymphadenoma in a series of 11 cases. Histologically, a lobular architecture surrounded by a dense fibrous stroma was present in all cases. The lobules were composed of epithelial cells admixtured with small lymphocytes and isolated or clustered large Reed-Sternberg-like (RS-L) cells. The epithelial cells were diffusely positive for the hair follicle stem cell markers CK15, PHLDA1, and for androgen receptor. No immunostaining for markers of sebaceous differentiation was found. Intraepithelial lymphocytes were predominantly CD3+, CD4+, FoxP3+ T cells. RS-L cells showed both strong Jagged-1 and Notch1 cytoplasmic immunostaining. Androgen-regulated NKX3.1 nuclear immunostaining was present in a subset of large intralobular cells in all cases. Double immunostaining showed coexpression of NKX3.1 and CD30 in a subset of RS-L cells. No immunostaining for lymphocytic or epithelial markers was present in RS-L cells. EGFR, PIK3CA, and FGFR3 somatic mutations were found by next-generation sequencing in 56% of the cases. We consider that cutaneous lymphadenoma is a distinct benign lymphoepithelial tumor with androgen receptor and hair follicle bulge stem cell marker expression, RS-L cell-derived Notch1 ligand, and common EGFR gene mutations.

Morphologic, Immunohistochemical, and Molecular Distinction Between Fibroepithelioma of Pinkus and "Fenestrated" Basal Cell Carcinoma

Fibroepithelioma of Pinkus (FEP) is a rare cutaneous neoplasm with a characteristic fenestrated architecture and a prominent spindle cell stromal component and which invariably pursues an indolent course. The classification of FEP has been much debated since its first description in 1953, with some arguing that it represents a variant of a basal cell carcinoma (BCC) while others view it as a variant of a trichoblastoma. Multiple previous immunohistochemical studies aiming to clarify this issue have yielded conflicting results. To date, there have been no molecular studies of FEP. We identified 16 cases of fenestrated follicular neoplasms and classified them as BCC or FEP based solely on histomorphologic criteria. CK20 immunohistochemistry supported this classification scheme, with FEP showing significantly more CK20-positive Merkel cells than BCC. We then analyzed a subset of these tumors by a targeted next-generation DNA sequencing platform. All the BCC cases harbored pathogenic PTCH1 mutations, confirming the diagnosis. By contrast, none of the FEP cases harbored a PTCH1 mutation or indeed any mutation known to be causally linked to the development of BCC. Our results suggest that FEP can be distinguished from BCC on morphologic, immunohistochemical, and molecular genetic grounds. We argue that FEP is better considered a benign follicular neoplasm and support its classification as a variant of trichoblastoma.

Clinical and dermoscopic features of Fibroepithelioma of Pinkus: case series with an emphasis on hypopigmented to pink lines intersecting at acute angles

Fibroepithelioma of Pinkus (FEP) is a subtype of basal cell carcinoma (BCC) that can clinically resemble intradermal nevi (IDN) and fibromas. We performed a retrospective review of consecutively biopsied lesions confirmed to be FEP on histopathology diagnosed from January 1, 2008 to April 8, 2019. Clinical (n = 48), contact non-polarized dermoscopy (NPD) (n = 44), and contact polarized dermoscopy (PD) (n = 22) images from 36 patients were reviewed. Mean age was 64.5 years (SD 15.1 years, range 24-86 years) at diagnosis of first FEP lesion. Most lesions were located on the torso (n = 28, 58.3%), followed by the lower extremity (n = 9, 18.8%). The most common differential diagnoses at the time of biopsy included BCC (n = 40) and nevus (other than IDN, n = 5). Clinically, FEP were pink (95.8%), scaly (66.7%) papules (77.1%) displaying disrupted skin markings (62.5%) and absence of hair follicles (87.5%). NPD revealed serpentine (97.7%), dotted (81.8%), or polymorphous vessels (86.4%), and hypopigmented to pink lines intersecting at acute angles (HPLA) (52.3%). PD demonstrated serpentine (95.5%), dotted (86.4%), or polymorphous vessels (81.8%), shiny white lines (50.0%), and HPLA (59.1%). Classic features of BCC such as arborizing vessels (n = 2), ulceration (n = 1), shiny white blotches and strands (n = 1), blue-gray ovoid nest (n = 1), and leaf-like areas (n = 1) were uncommon. FEP often presents as scaly, erythematous papules with disrupted skin markings and absence of hair follicles. Dermoscopy reveals polymorphous vessels with shiny white lines and HPLA.

Novel Presentation of Fibroepithelioma of Pinkus on the Ear of a Patient Treated on a Panamanian Humanitarian Mission

Fibroepithelioma of Pinkus (FEP) is traditionally classified as an unusual variant of basal cell carcinoma. It has non-specific clinical findings yet distinct histologic features. The diagnosis can be challenging for clinicians because it often mimics benign entities such as intradermal nevi. FEP typically occurs on the trunk, but many body sites can be involved including the head, neck, and genitalia. According to a PubMed search of articles indexed in MEDLINE using "Fibroepithelioma of Pinkus" and "ear" or "auricle," there are no reports of FEP specifically occurring on the ear. We describe the first case of FEP on the ear of a heavily sun-damaged male treated while on a military humanitarian mission to Panama. This case helps support the classification of FEP as a basal cell carcinoma variant and raises awareness for this entity as it may be encountered both on military humanitarian missions and in military clinics.

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.

Fibroepithelioma of Pinkus: Solitary tumor or sign of a complex gastrointestinal syndrome

Fibroepithelioma of Pinkus (FEP), which is considered to be an uncommon variant of basal cell carcinoma, has been described in association with other systemic diseases. However, no specific studies are currently available on this subject. The aim of our study was to evaluate the clinical and morphological characteristics of FEP and investigate whether this rare tumor is a single entity or seen in the context of a more complex syndrome. We retrospectively analyzed 49 cases of FEP diagnosed and excised in a single academic institution from 1995 to 2011. The tumors were mainly located on the trunk (77.55%), followed by the lower extremities (12.20%) and the head and neck (10.20%). In 9 of the 49 cases (18%), FEP was associated with gastrointestinal tumors. The abovementioned cases are presented in an attempt to make clinicians more aware of a possible association between FEP and gastrointestinal cancer. Although a possible underlying common genetic background between FEP and gastrointestinal tumors was not provided, our study suggests that patients with FEP should be screened for the occurrence of gastrointestinal tumors.

Fibroepithelioma of Pinkus is a true basal cell carcinoma developing in association with a newly identified tumour-specific type of epidermal hyperplasia

BACKGROUND

Fibroepithelioma of Pinkus (FEP) has long been viewed as a subtype of basal cell carcinoma (BCC). Recently, however, the proposal has been made that FEP represents a fenestrated trichoblastoma/trichoepithelioma. One of the main arguments is the presence of Merkel cells in FEP, which typically do not occur in BCC.

OBJECTIVES

As the new stem cell marker, PHLDA1 (TDAG51), labels trichoepithelioma but not BCC, our aim was to characterize its staining pattern in FEP. Because adnexal tumours have been viewed as recapitulating embryogenesis, we also examined PHLDA1 immunoreactivity in the skin of human embryos and fetuses.

METHODS

We studied immunohistochemically PHLDA1 staining in 31 FEPs, 14 BCCs and 16 trichoepitheliomas and compared this with its staining pattern in embryonic skin and with the distribution of Merkel cells.

RESULTS

In FEP, PHLDA1 labels the anastomosing network of thin cellular strands but not the basaloid nubbins. During embryogenesis, PHLDA1 stains the basal cell layer of the epidermis, as long as adnexal structures develop. Immunoreactivity for PHLDA1 correlates positively with the presence of Merkel cells.

CONCLUSIONS

We propose that the thin anastomosing network of PHLDA1-positive cells represents a type of epidermal hyperplasia specific to FEP. The multifocal BCCs that are PHLDA1-negative develop from this network which becomes incorporated into the tumour. Viewing the anastomosing network as a tumour-specific form of epidermal hyperplasia explains the hitherto enigmatic presence of Merkel cells in FEP.

Vulvar merkel carcinoma: a case report

This is a new case of Merkel cell carcinoma of the vulva. It is a rare neuroendocrine carcinoma with an aggressive behavior. Because of its rarity in this location, it is not clear whether it behaves differently from the usual neuroendocrine carcinomas of the skin. A case of a 63-year-old patient with vulvar Merkel carcinoma is presented. The clinical presentation, microscopic and immunohistochemical features, and treatment are discussed.

Tumor of follicular infundibulum is Basal cell carcinoma

Tumor of follicular infundibulum (TFI) is currently thought to be a benign epithelial neoplasm with follicular differentiation. It is encountered commonly in association with basal cell carcinoma (BCC), often as an incidental finding. We reexamined 24 cases of TFI and noted, often only focally, many changes typical of BCC, including palisading of cells at the periphery of aggregations, germinative cells, follicular germs in the absence of a follicular papilla, crowding of cells, individual necrotic neoplastic cells, fibromucinous stroma, and clefts between aggregations of neoplastic cells and stroma. Five cases were associated with BCC, and 2 of them showed obvious continuity between both types of lesions. Moreover, we observed recurrences of what seemed to be a completely removed BCC in which tiny columns of cells typical of TFI were present in surgical margins. Those findings prompted us to conclude that TFI may be one of many manifestations of BCC rather than a differential diagnosis of it.

Does the panel of cytokeratin 20 and androgen receptor antibodies differentiate desmoplastic trichoepithelioma from morpheaform/infiltrative basal cell carcinoma?

BACKGROUND

Evaluation of androgen receptor (AR) and cytokeratin 20 (CK20) expression can aid in distinguishing between conventional basal cell carcinoma (characteristically AR+, CK20-) and trichoepithelioma (frequently AR-, CK20+). Within these two groups of tumors, morpheaform/infiltrative basal cell carcinoma (mBCC) and desmoplastic trichoepithelioma (DTE) are particularly challenging to differentiate both clinically and histologically. We investigated whether AR and CK20 immunostains may distinguish between mBCC and DTE.

METHODS

Immunohistochemistry for AR and CK20 was performed on 15 DTEs and 31 mBCCs. Any immunoreactivity within the tumor for AR or CK20 was considered positive.

RESULTS

AR expression was seen in 13% (2/15) of DTE and 65% (20/31) of mBCC cases (chi-square p = 0.0011). CK20-positive Mërkel cells were identified in 100% (15/15) of DTE and 3% (1/31) of mBCC (chi-square p < 0.0001). The expected pattern of AR-, CK20+ immunophenotype was present in 87% (13/15) of DTE cases. In mBCC, 61% (19/31) was AR+, CK20-. No DTE was AR+, CK20- and no mBCC was AR-, CK20+.

CONCLUSIONS

Immunohistochemical stains for AR and CK20 are useful to differentiate DTE from mBCC. The AR-, CK20+ immunophenotype is sensitive (87%) and specific for DTE (100%). The AR+, CK20- immunophenotype is specific (100%) and moderately sensitive (61%) for mBCC.

Fibroepithelioma of pinkus in a 9-year-old boy: a case report

Fibroepithelioma of Pinkus (FEP) is a rare indolent variety of basal cell carcinoma that is typically polypoid and located on the trunk of adult males aged 40–60 years. Basal cell carcinoma (including FEP) is very rare in the pediatric population. We are reporting such a case occurring in a 9-year-old boy.

Basal cell carcinoma with fibroepithelioma-like histology in a healthy child: report and review of the literature

We report the case of a 13-year-old girl with a 7 mm plaque on the trunk. The mother of the patient reported that the lesion developed at the age of 3 and it was characterized by a slow growth. In 2003 a dermoscopic examination was executed and a diagnosis of dermical nevus was made. On examination at our department, a red-pinkish plaque with two small areas of ulceration was found on the anterior part of the trunk. At dermoscopic examination we observed vascular pattern with linear-irregular vessels, multiple blue-gray dots, blue-gray ovoid nests, and ulceration. A diagnosis of basal cell carcinoma was made and confirmed by histopathologic examination. The histopathologic specimen showed nests or lobules of basalioid cells associated with a surrounding loose fibromucinous stroma; two patterns were observed: adenoid-cystic and fibroepithelial. Some fibroepithelioma of Pinkus-like areas were present, where the fibrovascular stroma was very abundant with an arborizing network of long, thin cords of basaliod cells that extended downward from the epidermis and created a fenestrating pattern. The lesion was surgically excised. Basal cell carcinoma occurs rarely in children and is most often associated with an underlying condition that predisposes patients to the development of malignancy that was not present in our case.