New concepts on the histogenesis of eccrine neoplasia from keratin expression in the normal eccrine gland, syringoma and poroma

Dermal Duct Tumor: A Diagnostic Dilemma

Poromas or poroid tumors are a group of rare, benign cutaneous neoplasms derived from the terminal eccrine or apocrine sweat gland duct. There are four poroma variants with overlapping features: dermal duct tumor (DDT), eccrine poroma, hidroacanthoma simplex, and poroid hidradenoma, of which DDT is the least common. Clinically, the variants have a nonspecific appearance and present as solitary dome-shaped papules, plaques, or nodules. They can be indistinguishable from each other and a multitude of differential diagnoses, necessitating a better understanding of the characteristics that make the diagnosis of poroid neoplasms. However, there remains a paucity of information on these lesions, especially DDTs, given their infrequent occurrence. Herein, we review the literature on DDTs with an emphasis on epidemiology, pathogenesis, clinical features, diagnosis, and management.

Cutaneous eccrine inflammation and necrosis: review of inflammatory disorders affecting the eccrine apparatus including new associations

Despite being frequently overlooked during the examination of histopathological sections, eccrine sweat glands can offer clues for diagnosing various skin conditions. They provide important functions and can lead to several diseases when inflamed or injured. This review article provides information regarding eccrine physiology as well as well-established and novel entities that occur in association with eccrine gland pathology.

Incidental Clear Cell Syringoma of the Scalp in a Patient With Lichen Planopilaris

Syringomas are benign neoplasms of eccrine ducts; glycogen accumulation in the tumor cell cytoplasm results in a clear cell variant of syringoma. Syringoma and syringomatous proliferations (secondary to alteration of the eccrine sweat ducts) have been observed, albeit uncommonly, as an incidental finding in areas of alopecia on the scalp. A 71-year-old woman with scalp hair loss caused by lichen planopilaris had subclinical clear cell syringoma discovered as an incidental observation on evaluation of the biopsy specimen from an area of hair loss. Including our patient, scalp alopecia-associated syringoma or syringomatous proliferation has been described in a 47-year-old man and 16 women. The women ranged in age from 33 years to 83 years (median, 57 years). The duration of alopecia ranged from six months to 22 years; almost half of the patients (three of seven) had hair loss for 20 or more years. The frontal scalp was the most common location of alopecia; the parietal scalp and the entire scalp with diffuse hair loss were also frequent sites. Prior to biopsy, female pattern alopecia was the most common clinical diagnosis; lichen planopilaris and scarring alopecia were also frequent diagnoses. After the biopsy, pseudopelade was the most common diagnosis; lichen planopilaris and female pattern alopecia were also frequently observed. The pathogenesis of incidental syringomas and syringomatous proliferation in areas of scalp hair loss is postulated to be secondary to subclinical alopecia-related reactive changes.

Current Diagnosis and Treatment Options for Cutaneous Adnexal Neoplasms with Apocrine and Eccrine Differentiation

Adnexal tumors of the skin are a rare group of benign and malignant neoplasms that exhibit morphological differentiation toward one or more of the adnexal epithelium types present in normal skin. Tumors deriving from apocrine or eccrine glands are highly heterogeneous and represent various histological entities. Macroscopic and dermatoscopic features of these tumors are unspecific; therefore, a specialized pathological examination is required to correctly diagnose patients. Limited treatment guidelines of adnexal tumor cases are available; thus, therapy is still challenging. Patients should be referred to high-volume skin cancer centers to receive an appropriate multidisciplinary treatment, affecting their outcome. The purpose of this review is to summarize currently available data on pathogenesis, diagnosis, and treatment approach for apocrine and eccrine tumors.

Intralesional Electrocoagulation With Insulated Microneedle for the Treatment of Periorbital Syringomas: A Retrospective Analysis

BACKGROUND

Conventional treatment options for periorbital syringomas are often unsatisfactory because of inevitable surface damage from the procedure and frequent recurrence rate of the tumors.

OBJECTIVES

The authors sought to ascertain the efficacy and safety of intralesional electrosurgery utilizing a monopolar radiofrequency device with a single insulated microneedle for the treatment of periorbital syringomas.

METHODS

A retrospective analysis was performed employing data from medical records, routine questionnaires, and clinical photographs of 55 patients with periorbital syringoma who underwent intralesional electrosurgery.

RESULTS

Approximately one-half of the patients (50.9%) experienced marked resolution after 1 treatment. The lesion clearance rate increased and lesion severity decreased each time the treatment was repeated. No persistent therapy-related adverse event was found except transient erythema or crusting.

CONCLUSIONS

Intralesional electrosurgery with insulated microneedle is an effective and safe treatment option for periorbital syringomas.

LEVEL OF EVIDENCE: 4

Aggressive digital papillary adenocarcinoma: A clinicopathological study of 19 cases

BACKGROUND

Aggressive digital papillary adenocarcinomas (ADPA) are malignant tumors of sweat glands having recurrence/metastatic potential.

OBJECTIVE

We sought to describe the clinical/histopathological characteristics of a series of ADPA.

METHODS

This is a retrospective case series of 19 ADPA.

RESULTS

The tumors occurred in 17 men and 2 women (mean age: 47 years). They involved digits (15), big toe (3), and palm (1), and measured from 3 to 30 mm. They were mostly solid and cystic, with papillary projections and tubular structures. Atypia was mostly mild to moderate. Tumors tested positive for p63, keratin 7, keratin 77 (eccrine duct-specific), PHLDA1, and epithelial membrane antigen in most cases, and for carcinoembryonic antigen, smooth muscle actin, S100 protein, estrogen, progesterone, and androgen receptors in 50%. Mean Ki67 proliferation index was 15%. Local recurrence was observed in 4 cases. One patient had axillary lymph node metastasis. Histopathologic parameters were not predictive of evolution. Conservative surgical treatment, performed in 7 of 19 cases, did not result in more recurrences than amputation.

LIMITATIONS

The study was retrospective and the number of cases is small.

CONCLUSION

ADPA are histologically variable, but papillary projections are always present. Keratin 77 expression suggests an eccrine origin. P63 is helpful to exclude metastasis. Conservative surgery may be sufficient in some cases.

Syringoma: A clinicopathological study of 244 cases

BACKGROUND

Syringomas are benign tumours of the sweat glands, the most familiar clinical presentation of which is the presence of multiple lesions on the eyelids. The aim of our study was to determine the clinical and histological characteristics of a large series of patients and to examine anatomoclinical correlations.

PATIENTS AND METHODS

This was a retrospective study conducted in all of the cases of syringoma analysed at the cutaneous histopathology laboratory in Strasbourg between 1970 and 2008. The clinical elements, patient history and diagnostic data were collated. All slides were re-read in order to determine the microscopic characteristics of the lesions.

RESULTS

Two hundred and forty-four lesions were included. The sex ratio was 0.27 and the mean age was 42 years (8 to 85 years). Multiple syringomas were noted in 76% of cases, of which 29.2% were eruptive, and one case occurred in a setting of metastatic melanoma. The sites of predilection were the face (56.7%, of which 36.3% on the eyelids), the chest (18.1%) and the neck (17.5%) for the multiple forms. The lesions were in the form of papules (67%), either brown (34.2%) or flesh-coloured (19.8%). Pruritus was reported in 14 cases, including 4 at vulvar sites (out of a total of 8). A diagnosis of syringoma was made by the clinician in only 30.2% of the multiple forms, with mastocytosis being proposed in 7.1% of cases. The clear-cell forms (18 cases) presented no special clinical features.

CONCLUSION

Syringomas are frequently multiple and are seen mainly in women. They are found predominantly on the face and trunk, and lesions are generally brown and pruritic, a little-known feature that accounts for the degree of diagnostic confusion with mastocytosis. The vulvar forms, which are often pruritic, are poorly known. The eruptive forms may include a hormonal component.

Evaluation and management of the patient with multiple syringomas: A systematic review of the literature

Syringomas are benign adnexal tumors with distinct histopathologic features, including the characteristic comma ("tadpole") shaped tail comprised of dilated, cystic eccrine ducts. Clinically, syringomas typically present in adolescent females predominantly in the periorbital region. They may present as solitary or multiple lesions, and more rare sites of involvement include the genitals, palms, scalp, and the chest. Over the past 50 years, there have been >800 reported cases of syringoma either alone or in conjunction with a systemic syndrome, most commonly Down syndrome. The primary aim of this systematic review is to discuss the clinical features and associations of syringomas with a focus on the patient with multiple syringomas. Its secondary aims are to explore pathophysiology with a focus on multiple syringomas and provide comprehensive data on both traditional and novel treatments. Importantly, multiple syringomas present across a broad clinical spectrum. Though noted in many textbooks to be related to tumor syndromes, the association of syringomas with inherited tumor syndromes is only rarely reported in the literature. Despite multiple reported cases of syringoma, the pathophysiology remains poorly understood and treatment continues to pose a significant challenge.

Anatomoclinical study of 30 cases of sclerosing sweat duct carcinomas (microcystic adnexal carcinoma, syringomatous carcinoma and squamoid eccrine ductal carcinoma)

BACKGROUND

Microcystic adnexal carcinoma (MAC), syringomatous carcinoma (SC) and "Squamoid eccrine ductal carcinoma" (SEDC) are rare sclerosing adnexal tumours.

OBJECTIVE

To understand the histogenesis of these tumours and possible clinical implications.

METHODS

We conducted a retrospective study of 30 cases, 18 MAC, 5 SC and 7 SEDC reviewed and classified by a panel of dermatopathology experts, with immunohistochemical analysis of keratins, including K77, a new keratin specific of eccrine ducts, and PHLDA1 expressed in adnexal structures.

RESULTS

There was a strong female predominance, with only five cases occurring in men. Patients with MAC and SC were younger (mean age 56 and 47 years) than those with SEDC (mean age 81 years). The most common localization was the cheek in SC and SEDC and the periocular area in MAC. Two cases of SEDC were found in organ transplant patients. No recurrence or metastases were observed after complete surgery of MAC, or SC (mean follow-up 7.2 years and 4.7 years), whereas one case of SEDC recurred and another could not be fully excised. MAC and SC had similar histological features, except for cysts. In MAC, calcifications, granulomas, connection to follicles, keratin expression pattern, PHLDA1 positivity and K77 negativity indicated a follicular histogenesis, whereas in SC, K77 positivity and keratin expression pattern were consistent with a differentiation towards eccrine apparatus. SEDC was composed of strands centred by ducts and nests with squamous differentiation and displayed K77 ductal positivity in all cases, a finding consistent with an eccrine origin.

CONCLUSION

Our study demonstrated that MAC and SC have similar clinical characteristics, although histogenesis differs and show arguments for the individualization of SEDC.

[Eccrine porocarcinoma with Bowenoid changes: a challenging diagnosis of adnexal neoplasm]

Eccrine porocarcinoma is a rare malignant sweat gland tumor, representing less than 0.01% of all cutaneous neoplasms, with eccrin differentiation. Its acrosynringeal origin and physiopathology still remain discussed. The prognosis of this carcinoma is held to be poor with a significant risk of lymph node metastasis and local recurrence. Also, this not specific tumor can be a challenging histological diagnosis, in particular, in Bowenoid variant. We report a case of Bowenoid and keratinizing variant of eccrine porocarcinoma of the left ring finger with pejorative evolution and initial diagnosis of infiltrating squamous cell carcinoma arising in Bowen's disease. The knowledge of these patterns and identification of eccrine differentiation of the tumor are essential for the diagnosis and for adapted therapeutic care.

K5/K14-positive cells contribute to salivary gland-like breast tumors with myoepithelial differentiation

Salivary gland-like tumors of the breast show a great variety of architectural patterns and cellular differentiations such as glandular, myoepithelial, squamous, and even mesenchymal phenotypes. However, currently little is known about the evolution and cellular differentiation of these tumors. For that reason, we performed an in situ triple immunofluorescence lineage/differentiation tracing (isTILT) and qRT-PCR study of basal (K5/K14), glandular (K7/K8/18), and epidermal-specific squamous (K10) keratins, p63, and smooth muscle actin (SMA; myoepithelial marker) with the aim to construct and trace different cell lineages and define their cellular hierarchy in tumors with myoepithelial differentiation. isTILT analysis of a series of 28 breast, salivary, and lacrimal gland tumors, including pleomorphic adenomas (n=8), epithelial-myoepithelial tumors (n=9), and adenoid cystic carcinomas (n=11) revealed that all tumor types contained K5/K14-positive progenitor cells in varying frequencies from a few percent up to 15%. These K5/K14-positive tumor cells were found to differentiate to glandular- (K8/18-positive) and myoepithelial-lineage (SMA-positive)-specific cells and were also shown to generate various heterologeous cell differentiations such as squamous and mesenchymal progenies. p63 was co-expressed with K5/K14 in basal-like progenitor cells, myoepithelial, and squamous cells but not in glandular cells. Our results show that the corresponding counterpart tumors of breast and salivary/lacrimal glands have identical cellular compositions. Taken together, our isTILT and RNA-expression data indicate that look-alike tumors of the breast represent a special subgroup of basal-type tumors with benign or usually low malignant potential.

Unusual sites for poromas are not very unusual: a survey of 101 cases

BACKGROUND

Poromas are benign adnexal tumours generally believed to be of eccrine origin, which usually develop on palmoplantar sites. However, it is thought that a percentage of poromas develop on non-palmoplantar or 'unusual' sites.

AIM

To review cases of poromas with reference to their clinicoepidemiological characteristics, paying particular attention to the those located on sites other than the palms and soles.

METHODS

All histologically confirmed poromas seen at our department between 1994 to 2012 were reviewed. The clinicoepidemiological data recorded included age at diagnosis, gender, location, size, colour, and preoperative and pathological diagnoses.

RESULTS

In total, 101 poromas were reviewed, corresponding to 0.0058% of all the epithelial skin tumours biopsied in our department. The mean age was 65.05 years (range 30-100 years), and the male to female ratio was 1.52. All the lesions were solitary and asymptomatic, with no sign of bleeding. The most common presentation was a red or reddish lesion, particularly at palmoplantar sites, where 33 (32.7%) of the 101 poromas were located, Poromas found at other affected sites were more usually skin-coloured, and these lesions included 7 neoplasms located in the armpits and 18 on the head and neck. The correct preoperative diagnosis was made in 12 cases of 33 detected poromas (36%), all of which were localized to the palmoplantar surfaces.

CONCLUSIONS

Based on our experience, we consider that there are no 'unusual' sites for poromas, and palmoplantar poromas were in fact in the minority. Furthermore, some localizations suggest derivation of these palmoplantar poromas from the folliculosebaceous apocrine unit.

Synthesis of porcine pCLCA2 protein during late differentiation of keratinocytes of epidermis and hair follicle inner root sheath

Despite the discovery of the widely expressed CLCA (chloride channel regulators, calcium-activated) proteins more than 15 years ago, their seemingly diverse functions are still poorly understood. With the recent generation of porcine animal models for cystic fibrosis (CF), members of the porcine CLCA family are becoming of interest as possible modulators of the disease in the pig. Here, we characterize pCLCA2, the porcine ortholog of the human hCLCA2 and the murine mCLCA5, which are the only CLCA members expressed in the skin. Immunohistochemical studies with a specific antibody against pCLCA2 have revealed a highly restricted pCLCA2 protein expression in the skin. The protein is strictly co-localized with filaggrin and trichohyalin in the granular layer of the epidermis and the inner root sheath of the hair follicles, respectively. No differences have been observed between the expression patterns of wild-type pigs and CF transmembrane conductance regulator(-/-) pigs. We speculate that pCLCA2 plays an as yet undefined role in the structural integrity of the skin or, possibly, in specialized functions of the epidermis, including barrier or defense mechanisms.

Mutations in AEC syndrome skin reveal a role for p63 in basement membrane adhesion, skin barrier integrity and hair follicle biology

BACKGROUND

AEC (ankyloblepharon-ectodermal defects-clefting) syndrome is an autosomal dominant ectodermal dysplasia disorder caused by mutations in the transcription factor p63. Clinically, the skin is dry and often fragile; other features can include partial eyelid fusion (ankyloblepharon), hypodontia, orofacial clefting, sparse hair or alopecia, and nail dystrophy.

OBJECTIVES

To investigate how p63 gene mutations affect gene and protein expression in AEC syndrome skin.

METHODS

We performed microarray analysis on samples of intact and eroded AEC syndrome skin compared with control skin. Changes were verified by quantitative real-time reverse transcription-polymerase chain reaction and, for basal keratinocyte-associated genes, by immunohistochemistry and analysis of microdissected skin.

RESULTS

We identified significant upregulation of six genes and downregulation of 69 genes in AEC syndrome skin, with the main changes in genes implicated in epidermal adhesion, skin barrier formation and hair follicle biology. There was reduced expression of genes encoding the basement membrane proteins FRAS1 and collagen VII, as well as the skin barrier-associated small proline-rich proteins 1A and 4, late cornified envelope protein 5A, hornerin, and lipid transporters including ALOX15B. Reduced expression of the hair-associated keratins 25, 27, 31, 33B, 34, 35, 81 and 85 was also noted. We also confirmed similar alterations in gene expression for 26 of the 75 genes in eroded AEC scalp skin.

CONCLUSIONS

This study identifies specific changes in skin structural biology and signalling pathways that result from mutant p63 and provides new molecular insight into the AEC syndrome phenotype.

Origin and differentiation of breast nipple syringoma

Similarities in morphology and in glandular and squamous differentiation patterns amongst syringomas of the breast nipple and of the skin suggest a common nature, but the origin of nipple syringoma remains undefined. Using triple immunofluorescence analysis, we found that cells immunopositive for basal keratins K5 and 14 undergo differentiation into glandular and squamous cell lineages. Both tumour types expressed K10, indicative of squamous lineage, but there were specific differences in their glandular lineage. In contrast to the breast nipple syringoma, which expressed glandular keratins K8/18/19, syringoma of the skin only expressed the glandular keratin K19. Therefore, syringomas of the breast nipple and of the skin resemble glandular lineages of the breast nipple duct or eccrine duct epithelium, respectively. From these results we conclude that K5/14-positive cells of the breast nipple ducts are the putative cells of origin for syringomas of the nipple, which highlights the organotypic glandular differentiation potential.

Multiple eccrine poromas in the paw of a dog

A 5-year-old, spayed female boxer dog presented to the referring veterinarian with a year-long history of swelling, ulceration and pain in the pawpad of the fourth digit of the right forelimb. Histologically, the pawpad was expanded by a mass composed of small polygonal cells forming broad bands and trabeculae within the lower epidermis that often infiltrated and replaced the overlying keratinocytes and that extended into the dermis. Lobules of eccrine glands within the deep dermis occasionally had one or more eccrine ducts that were lined by neoplastic ductal epithelial cells that formed papillary projections lined by one to two layers of neoplastic cells. Approximately 1 month after amputation of the fourth digit pad, several smaller nodular masses developed in multiple digital pads and the metacarpal pad of the same paw. All of the neoplasms were histologically identical to eccrine poroma (juxtaepidermal acrospiroma), a common benign neoplasm in humans that originates from the acrosyringium and upper dermal duct of eccrine glands. To the authors' knowledge this is the first report documenting an eccrine poroma in a dog.

Glucocorticoid receptor regulates overlapping and differential gene subsets in developing and adult skin

We have previously shown that the glucocorticoid receptor (GR) is required for skin homeostasis and epidermal barrier competence. To understand the transcriptional program by which GR regulates skin development, we performed a microarray analysis using the skin of GR(-/-) and GR(+/+) mice of embryonic d 18.5 and identified 442 differentially expressed genes. Functional clustering demonstrated overrepresentation of genes involved in ectoderm/epidermis development. We found strong repression of genes encoding proteins associated with the later stages of epidermal differentiation, such as several small proline-rich proteins (Sprrs) and corneodesmosin (Cdsn). This, together with the up-regulation of genes induced earlier during epidermal development, including the epithelial-specific gene transcripts E74-like factor 5 (Elf5) and keratin 77 (Krt77), fits with the phenotype of defective epidermal differentiation observed in the GR(-/-) mice. We also found down-regulation of the antimicrobial peptide defensin β 1 (Defb1) and FK506-binding protein 51 (Fkbp51). Skin developmental expression profiling of these genes and studies in cultured keratinocytes from GR(-/-) and wild type embryos demonstrated that gene regulation occurred in a cell-autonomous manner. To investigate the consequences of GR loss in adult epidermis, we generated mice with inducible inactivation of GR restricted to keratinocytes (K14-cre-ER(T2)//GR(loxP/loxP) mice). K14-cre-ER(T2)//GR(loxP/loxP) mice featured thickened skin with increased keratinocyte proliferation and impaired differentiation. Whereas Krt77 and Elf5 expression remained unaffected by loss of GR in adult epidermis, Fkbp51, Sprr2d, and Defb1 were strongly repressed. Importantly, we have identified both Fkbp51 and Defb1 as direct transcriptional targets of GR, and we have shown that GR-mediated regulation of these genes occurs in both developing and adult epidermis. We conclude that both overlapping and differential GR targets are regulated in developing vs. adult skin.

A unique presentation of eccrine hamartoma: eccrine nevus with abnormal eccrine structures and angiomyxoid stroma

Eccrine hamartomas are very rare lesions usually presenting in early childhood, with variable clinical presentations. Local hyperhidrosis is often noticed. These lesions are all characterized by an increase in number and/or size of normal eccrine glands. We report the case of a hamartomatous lesion composed of eccrine structures and prominent angiomyxoid stroma, diagnosed in a 9-year-old girl. In this lesion, eccrine structures were not normal eccrine coils or ducts but ramified strands of small eosinophilic cells, containing a few eccrine ducts. These epithelial structures expressed carcinoembryonic antigen, cytokeratin 14, and cytokeratin 77, in a pattern suggesting ductal eccrine differentiation. The mesenchymatous component contained numerous capillary vessels in an abundant myxoid stroma. It was organized concentrically around the epithelial structures. This angiomyxoid stroma was somewhat reminiscent of mucinous eccrine nevi and eccrine angiomatous hamartomas. We propose to describe this unique lesion inside the group of eccrine nevi with the term "angiomyxoid eccrine nevus."

The human keratins: biology and pathology. Histochem Cell Biol. 2008;129:705-733. [PMID: 18461349 PMCID: PMC2386534 DOI: 10.1007/s00418-008-0435-6]

The keratins are the typical intermediate filament proteins of epithelia, showing an outstanding degree of molecular diversity. Heteropolymeric filaments are formed by pairing of type I and type II molecules. In humans 54 functional keratin genes exist. They are expressed in highly specific patterns related to the epithelial type and stage of cellular differentiation. About half of all keratins—including numerous keratins characterized only recently—are restricted to the various compartments of hair follicles. As part of the epithelial cytoskeleton, keratins are important for the mechanical stability and integrity of epithelial cells and tissues. Moreover, some keratins also have regulatory functions and are involved in intracellular signaling pathways, e.g. protection from stress, wound healing, and apoptosis. Applying the new consensus nomenclature, this article summarizes, for all human keratins, their cell type and tissue distribution and their functional significance in relation to transgenic mouse models and human hereditary keratin diseases. Furthermore, since keratins also exhibit characteristic expression patterns in human tumors, several of them (notably K5, K7, K8/K18, K19, and K20) have great importance in immunohistochemical tumor diagnosis of carcinomas, in particular of unclear metastases and in precise classification and subtyping. Future research might open further fields of clinical application for this remarkable protein family.