Bcl-2, CD34 and CD10 expression in basaloid follicular hamartoma, vellus hair hamartoma and neurofollicular hamartoma demonstrate full follicular differentiation

"Kissing" basaloid follicular hamartomas of the eyelid

Basaloid follicular hamartomas (BFH) are rare, benign, cutaneous adnexal tumors characterized by branching cords and anastomosing strands of basaloid cells in a loose, fibrous stroma. BFH exhibit variable clinical presentations although they are commonly observed as skin to flesh colored papules and are diagnosed based on histological features. Common systemic diseases associated with BFH include alopecia, myasthenia gravis, and palmoplantar pitting. BFH of the eyelid is extremely rare with only five cases reported in the literature to date. Congenital "kissing" lesions have only previously been reported with nevi. Here we present a novel case of congenital "kissing" basaloid follicular hamartoma of the right upper and right lower eyelid and histological examination revealed intradermal nodules of basaloid cells forming reticulated strands, pseudohorn cysts, mucinous stroma and palisading with CD34 and Bcl-2 expression in the stromal fibroblasts and periphery, respectively. This article is protected by copyright. All rights reserved.

Basaloid Follicular Hamartoma: An Additional Criterion of Nevoid Basal Cell Carcinoma Syndrome

ABSTRACT

Basaloid follicular hamartoma (BFH) is a rare, benign follicular neoplasm which typically presents as brown to skin-colored papules on the face, scalp, and trunk. Histologically, BFH consists of cords and strands of basaloid cells forming cystic structures with scant stroma and should be distinguished from infundibulocystic basal cell carcinoma to avoid overly aggressive treatment. Although BFH has been found to be associated with distinct syndromes, including alopecia, myasthenia gravis, and cystic fibrosis, there is often clinical, histopathologic, and genetic overlap with nevoid basal cell carcinoma syndrome (NBCCS). In this article, we describe a case of a 13-year-old patient with NBCCS who presented with multiple BFHs and propose that it its inclusion into the diagnostic criteria for NBCCS be considered.

Orofacial Manifestations Assisting the Diagnosis of Cowden Syndrome in a Middle-Aged Patient: Case Report and Literature Overview

Middle-aged and old adults (≥ 50 years) diagnosed with Cowden syndrome (CS) with orofacial manifestations are uncommon. We describe a case of CS in a 53-year-old female showing "narrow bird-like" face, macrocephaly, acral keratoses, oral candidiasis, burning in the mouth, and multiple asymptomatic papillomatous lesions with a cobblestone pattern distributed on the alveolar ridge, tongue, buccal mucosa, and commissure. The histopathological features of lesions of the oral mucosa were those of papillary fibroepithelial hyperplasia. Immunohistochemistry revealed strong positivity for PTEN and p53 in most epithelial cells, while the expression of Bcl-2, S-100, and Ki-67 was weak/negative. According to a review conducted in PubMed, Web of Science, Embase, and Scopus for the analysis of reports of CS individuals ≥ 50 years with orofacial manifestations, 56 cases have been described in literature. Predilection for women was observed, with a female:male ratio of 2.3:1. Thirty-five (62.5%) individuals developed some malignant neoplasms. Oral health providers should be aware of the orofacial aspects of CS, including multiple papillomatosis, which can be an important criterion for diagnosis. Since malignancies may occur in older adults with CS, the need for strict surveillance is necessary. The present case has been under follow-up for 7 years without evidence of other manifestations.

Basaloid follicular hamartomas in pediatric Basal Cell Nevus Syndrome: A diagnostic challenge

Basal Cell Nevus Syndrome (BCNS) is an autosomal dominant inherited disease caused by PTCH1 (9q22.3‐q31) germline mutations. Skin manifestations are mainly characterized by hyperkeratosis of the palms and soles, palmoplantar pits and a strong predisposition to develop multiple basal cell carcinomas (BCCs). Recently, it has been hypothesized that basaloid follicular hamartomas (BFH) could be included in BCNS skin features. We present three pediatric cases of GS with BCCs and BFHs. Clinical, dermoscopic and immunohistochemical tools are reported.

Basaloid follicular hamartoma of the eyelid in a pediatric patient

Purpose

We report a case a pediatric patient with an eyelid lesion found to be a basaloid follicular hamartoma.

Observations

A six-year-old female with juvenile diabetes who presented with a benign eyelid lesion harboring an aberrant eyelash.

Conclusions and Importance

Basaloid follicular hamartoma is a rare benign neoplasm arising from hair follicles. These lesions can resemble basal cell carcinomas and require complete excision.

Basaloid tumors arising from seborrheic keratosis: Malignant basal cell carcinoma or benign basaloid follicular hamartomatous proliferation?

BACKGROUND

Basaloid tumors arising from seborrheic keratosis (SK) that resembled basal cell carcinoma (BCC) were infrequently observed in our patients. They also exhibited morphologic features similar to those of trichoblastoma or basaloid follicular hamartoma.

METHODS

We retrospectively collected cases of SK with basaloid tumors from 2001 to 2017. Ten cases of BCC, five of nevus sebaceus with trichoblastoma, five of trichoblastoma, and five of trichoepithelioma were included as controls. Tumor-associated antigens Bcl-2, CD10, PHLDA1, and CK20 were tested. Antigenic markers CD34 and CD10 were used to analyze peritumoral stroma features and Ki-67 and pHH3 to measure the mitotic activity.

RESULTS

Ten cases of SK with basaloid tumors were found and all located in non-sun-exposed areas, including five men and five women, with a mean age of 61 years. A distinct PHLDA1 staining was not observed. The staining patterns of basaloid tumor lobules associated with SK were similar to the benign control group. Bcl-2 staining in the tumor lobules was mostly negative. Peritumoral CD10 stain and CK20-positive Merkel cells in the lobules were observed and the mitotic counts were low.

CONCLUSION

Basaloid tumors arising from SK are not always BCC. They were all benign follicular hamartomatous proliferation in this case series.

[Histopathological study of basaloid follicular hamartoma]

INTRODUCTION

Basaloid follicular hamartoma (BFH) is a rare tumor first described in 1985. It bears clinical and histologic similarities with basal cell carcinoma (BCC), in particular the so-called infundibulocystic form. We performed a single-center clinicopathological study of a series of typical cases of this entity that is occasionally difficult to diagnose.

MATERIALS AND METHODS

All cases of BFH seen at the Dermatopathology Laboratory of Strasbourg University Hospital were included and analyzed by means of HE staining and Ber-EP4 and PHLDA1 immunolabelling. Diagnosis was made in the event of basaloid proliferation with anastomosing cords developed from a hair follicle. Clinical data were collected from clinical files.

RESULTS

We identified 15 cases in 13 patients of mean age 44.8 years (range: 4 to 90) and the sex-ratio was 5/8. Lesions consisted of flesh-colored papules measuring 0.3 to 1.2cm in diameter, without any preferential site. Three patients had multiple lesions consisting of several coalescent papules on a breast for one, sparse papules on the back for another, and hundreds of linear unilateral BFHs, associated with osseous abnormalities, characteristic of Happle-Tinschert syndrome, for the third. All tumors were limited to the superficial and mid dermis, with a vertical orientation and connection to the epidermis in 14 of the 15 patients. In some cases, the outermost cells were basophilic while the central cells were eosinophilic. Peripheral palisading and clefting were frequently observed. Keratin cysts or sebaceous ducts were consistently present, indicating follicular differentiation. Ber-EP4+ cells were restricted to the periphery of the cords and PHLDA1 was weakly expressed.

DISCUSSION

BFH is a rare entity that must be differentiated from BCC. It presents as solitary or multiple lesions, either grouped in plaques or with a generalized or linear unilateral distribution. Generalized BFH may be associated with autoimmune diseases and linear unilateral BFH with osseous, dental and cerebral abnormalities in Happle-Tinschert syndrome. It is important to distinguish BFH from BCC to avoid inappropriate aggressive treatment.

Hamartomas of skin and soft tissue

Hamartomas are benign lesions composed of aberrant disorganized growth of mature tissues. Choristomas are similar, except that they are composed of tissues not normally found at the anatomic site in which the lesion is arising. A wide range of hamartomas and choristomas can arise in the skin and soft tissue. Some of these may cause diagnostic difficulty and potentially be mistaken for neoplasms. Some neoplasms may resemble hamaratomas. Here we review the current clinical and pathologic features of these lesions, both common and rare, and discuss how to distinguish them from other entities in the differential diagnosis.

Histologic Mimics of Basal Cell Carcinoma

CONTEXT

- Basal cell carcinoma (BCC) is the most common human malignant neoplasm and is a frequently encountered diagnosis in dermatopathology. Although BCC may be locally destructive, it rarely metastasizes. Many diagnostic entities display morphologic and immunophenotypic overlap with BCC, including nonneoplastic processes, such as follicular induction over dermatofibroma; benign follicular tumors, such as trichoblastoma, trichoepithelioma, or basaloid follicular hamartoma; and malignant tumors, such as sebaceous carcinoma or Merkel cell carcinoma. Thus, misdiagnosis has significant potential to result in overtreatment or undertreatment.

OBJECTIVE

- To review key features distinguishing BCC from histologic mimics, including current evidence regarding immunohistochemical markers useful for that distinction.

DATA SOURCES

- Review of pertinent literature on BCC immunohistochemistry and differential diagnosis.

CONCLUSIONS

- In most cases, BCC can be reliably diagnosed by histopathologic features. Immunohistochemistry may provide useful ancillary data in certain cases. Awareness of potential mimics is critical to avoid misdiagnosis and resulting inappropriate management.

Basaloid follicular hamartoma

Basaloid follicular hamartoma is a benign lesion of important consideration because it can be mistaken both clinically and histologically for basal cell carcinoma. The formation of basaloid follicular hamartoma has been linked to a mutation in the patched gene, which is part of the same pathway implicated in nevoid basal cell carcinoma syndrome. While these hamartomas are considered benign lesions, malignant growths have been reported to arise within them, which raises the question, "Is basaloid follicular hamartoma a premalignant lesion?" Correct identification allows for periodic monitoring for malignant transformation, while sparing patients unnecessary surgery. Treatment strategies, including experimental therapies, are reviewed.

A novel PTCH1 germline mutation distinguishes basal cell carcinoma from basaloid follicular hamartoma: a case report

Introduction

Nevoid basal cell carcinoma syndrome is a rare autosomal dominant disorder characterized by numerous basal cell carcinomas, odontogenic keratocysts of the jaws and developmental defects. The disorder results from mutations in the PTCH1 gene.

Case presentation

A 15-year-old boy presented to our dental clinic with multiple jaw cysts. The patient had broad confluent eyebrows, a broad base of the nose, frontal bossing and palmoplantar pits. Examination of the jaw cysts revealed many keratinizing cysts without granular cell layers a finding that raised the suspicion of nevoid basal cell carcinoma. Radiological examinations showed calcification of the falx cerebri, spina bifida, bifid thoracic ribs and frontal bossing. Histopathological examination showed basaloid proliferation in the upper dermis with follicular differentiation surrounded by a loose mucinous stroma and retraction artifacts. These features make it difficult to differentiate between nevoid basal cell carcinoma and basaloid follicular hamartoma, especially the presence of these findings on a non-hairy area. BCL-2 staining was positive in the periphery of the basaloid proliferation, which is typical of basaloid follicular hamartoma, and not in a diffuse pattern, which is typical of nevoid basal cell carcinoma. The proband's siblings and parents were healthy with no family history of this condition in the extended family. Since histology was equivocal and palmoplantar pits are seen in both basaloid follicular hamartoma and nevoid basal cell carcinoma, molecular genetic investigation was necessary to differentiate between the two potential diagnoses. After sequencing the entire PTCH1 gene, we detected a single nucleotide deletion (c.1291delC) in codon 431 of the PTCH protein, which resulted in a premature stop translation at residue 431. This de novo mutation was not detected in both parents and in 100 normal volunteers of matching ethnicity.

Conclusion

Screening the PTCH1 gene for mutations helped to differentiate between basaloid follicular hamartoma and nevoid basal cell carcinoma and confirmed the diagnosis.