Clinical, onychoscopic, nail clipping, and histopathological findings of malignant onychopapilloma

This report describes the clinical, onychoscopic, nail clipping, and histopathologic features of a malignant onychopapilloma. A 71-year-old male presented to our outpatient clinic for a stable, asymptomatic lesion on his left middle finger that had been present for 2 years. Prior nail clipping histopathology showed nail plate thinning with subungual abnormal onychocytes. Clinical examination revealed a 2-mm-wide streak of longitudinal xanthonychia extending to the proximal nail fold, with distal hyperkeratosis and onycholysis. Onychoscopy showed irregular longitudinal nail plate ridging with scattered punctate hemorrhagic foci. An excisional nail unit biopsy demonstrated cellular atypia of the nail bed epithelium, matrix metaplasia, longitudinal abnormal onychocytes, increased Ki-67 staining, and negative HPV immunoperoxidase staining, confirming the diagnosis of malignant onychopapilloma.

Onychomatricomas: A 41-Case Series to Assess Surgical Outcome

BACKGROUND

Onychomatricoma (OM) is a rare benign tumor of the nail matrix. Treatment is surgical, but data are currently limited.

OBJECTIVE

To review all cases of OM operated in their department and to assess the link between the location on the nail plate, the thickness and width of the lesion, and the postoperative outcomes.

MATERIALS AND METHODS

Records of 62 patients were retrieved from their department's database over a 25-year period (1998-2023).

RESULTS

Of the 62 patients, 41 were eligible. In total, 58% of OM occupied a width of a quarter of the nail plate, 51% had a plate thinner than 3 mm, and 51% were laterally located. Of the 41 patients included, 29 had a tangential excision and 12 underwent lateral longitudinal excision. Among the tangential excision group, 71% had normal nail regrowth. Onychomatricoma thicker than 3 mm and involving the total nail plate width had a sequelae in 60% of cases.

CONCLUSION

Tangential excision of onychomatricomas allows a normal nail regrowth in 71% of cases. The risk of sequelae increases for tumors thicker than 3 mm and involving the total nail plate width. Medial or lateral location seems to have no influence.

RB1 loss in the mesenchymal component of onychomatricoma

BACKGROUND

Onychomatricoma is a nail neoplasm that usually presents as longitudinal nail plate thickening, involving either the partial or whole nail. Histopathologically, it is characterized by deep invaginations of the proliferating nail matrix and proliferation of CD34+ and CD10+ spindle cells with collagenous to myxoid stroma. Onychomatricoma has been considered a fibroepithelial neoplasm. Recently, RB1 loss has been verified using array comparative genomic hybridization.

METHODS

This study investigated the RB1 status in onychomatricoma with morphological methods.

RESULTS

Six patients with onychomatricoma were included in the study. RB1 status was assessed using immunohistochemical staining and fluorescence in situ hybridization. Immunohistochemical staining showed that all six cases experienced RB1 loss in the mesenchymal component of onychomatricoma but not in the proliferated nail matrix. Fluorescence in situ hybridization in five cases showed a monoallelic deletion of the RB1 locus in the mesenchymal component but not in the proliferated nail matrix.

CONCLUSIONS

RB1 loss was observed only in the mesenchymal component of onychomatricoma. Our findings suggest that the proliferated nail matrix in onychomatricoma represents reactive hyperplasia of various degrees secondary to neoplastic mesenchymal proliferation. This indicates that onychomatricoma should be recognized as an RB1-deleted soft tissue neoplasm rather than a fibroepithelial neoplasm.

Seven Plus One Steps to Assess Pigmented Nail Bands (Melanonychia Striata Longitudinalis)

Melanonychia striata longitudinalis might involve one or more fingers and/or toes and might result from several different causes, including benign and malignant tumors, trauma, infections, and activation of melanocytes that might be reactive or related to the pigmentary trait, drugs and some rare syndromes. This broad differential diagnosis renders the clinical assessment of melanonychia striata particularly challenging. Nail matrix melanoma is relatively rare, occurs almost always in adults involves more frequently the first toe or thumb. The most common nail unit cancer, squamous cell carcinoma / Bowen disease (SCC) of the nail matrix is seldom pigmented. Histopathologic examination remains the gold standard for melanoma and SCC diagnosis, but excisional or partial biopsies from the nail matrix require training and is not routinely performed by the majority of clinicians. Furthermore, the histopathologic evaluation of melanocytic lesions of the nail matrix is particularly challenging, since early melanoma has only bland histopathologic alterations. Dermatoscopy of the nail plate and its free edge significantly improves the clinical diagnosis, since specific patterns have been associated to each one of the causes of melanonychia. Based on knowledge generated and published in the last decades, we propose herein a stepwise diagnostic approach for melanonychia striata longitudinalis: 1) Hemorrhage first 2) Age matters 3) Number of nails matters 4) Free edge matters 5) Brown or gray? 6) Size matters 7) Regular or irregular and, finally, "follow back".

Pigmented Onychomatricoma Presenting as Pachymelanonychia Striata: A Case Report and Review of Literature

Introduction

Onychomatricoma is a fibroepithelial tumor derived from the nail matrix and onychodermis. Many clinical and histological variants have been described. Pigmented onychomatricoma is a rare variant which presents as longitudinal pachymelanonychia.

Case Presentation

We report the details of a 41-year-old female who presented with blackening and thickening involving more than half of the left middle fingernail for the past 10 years. Dorsal plate onychoscopy revealed longitudinal parallel white, gray, and black bands, while onychoscopy of the distal free edge demonstrated a thickened nail plate with "wood worm" cavities. The histopathological examination of the excised tumor revealed a pigmented onychomatricoma.

Conclusions

Onychomatricoma is one of the nail tumors presenting as pachyonychia striata apart from onychocytic matricoma and onychocytic carcinoma. A pigmented onychomatricoma may closely mimic fungal melanonychia, pigmented onychopapilloma, pigmented ungual Bowen's disease, and ungual melanoma. Noninvasive techniques like onychoscopy and imaging studies like ultrasonography and magnetic resonance imaging are helpful in differentiating it from pigmented ungual Bowen's disease and ungual melanoma, even though diagnostic confirmation requires an excisional biopsy.

Onychomatricoma: a clinicopathological, immunohistochemical, and molecular study of 10 cases highlighting recurrent RB1 deletion and the potential diagnostic value of LEF-1

AIMS

Onychomatricoma (OM), an uncommon benign fibroepithelial neoplasm of the nail unit, is sometimes diagnostically challenging for clinicians and pathologists. OM consistently expresses CD34, but no specific immunohistohemical markers or recurrent genetic alterations have been identified to date. Recent studies have suggested that Wnt signalling is a key molecular characteristic of OM.

METHODS AND RESULTS

Ten cases were analysed: four classical OM including two with pleomorphic cells; two superficial acral fibromyxoma-like variants of OM; three micropapilliferum variants of OM including one with pleomorphic cells; and one proliferating variant of OM. Immunohistochemically, the spindle cells were positive with CD34 (n = 10) and CD99 (n = 1), with focal reactivity for CD10 (n = 5). The epithelial component of the tumours expressed immunopositivity for LEF-1. Using array comparative genomic hybridization (aCGH), we demonstrated that all OM, including its variants that were tested (n = 8), harboured a few copy number alterations with losses of whole or part of chromosome 13 including the RB1 gene (n = 8) and chromosome 16 (n = 6).

CONCLUSION

We report a recurrent loss of RB1 (13q) as a possible driver molecular event in OM indicating a relationship between OM and other lesions of the spectrum of the so-called '13q/RB1' family of tumours. We did not identify a role for the Wnt/beta-catenin signalling pathway, as has been proposed in a recent study. LEF-1 could be a potential sensitive and specific marker of OM and should be used in the differential diagnosis between OM, superficial acral fibromyxoma, and the CD34-positive fibrosing family of tumours.

Diagnosis and surgical treatment of benign nail unit tumors

Little is known about benign non-melanocytic nail tumors, probably due to their low pathogenicity. They are commonly misdiagnosed as inflammatory or infective diseases. They have various features, depending on the type of tumor and its location in the nail apparatus. The typical sign of a tumor is the presence of a mass and/or secondary nail changes from damaged nail structures. In particular, if a single digit is affected by a dystrophic sign or a symptom is reported without any explanation, the presence of a tumor should always be ruled out. Dermatoscopy helps to enhance visualization of the condition and in many cases supports the diagnosis. It may also assist in identifying the right place to biopsy, but it never replaces surgery. Most common non-melanocytic nail tumors are analyzed in this paper, including glomus tumor, exostosis, myxoid pseudocyst, acquired fibrokeratoma, onychopapilloma, onychomatricoma, superficial acral fibromyxoma and subungual keratoacanthoma. The aim of our study is to review the main clinical and dermatoscopic characteristics of the most common benign non-melanocytic nail tumors, to correlate them with the histopathology and to advise practitioners of the best surgical management.

Molecular characterization of onychomatricoma: Spatial profiling reveals the role of onychofibroblasts in its pathogenesis

Onychomatricoma (OM) is a rare nail unit tumour with a characteristic presentation of finger-like projections arising from the nail matrix. Due to the lack of transcriptome information, the mechanisms underlying its development are largely unknown. To characterize molecular features involved in the disease pathogenesis, we used digital spatial profiling (DSP) in 2 cases of OM and normal control nail units. Based on the histological evaluation, we selectively profiled 69 regions of interest covering epithelial and stromal compartments of each tissue section. Dermoscopic and histopathologic findings were reviewed in 6 cases. Single-cell RNA sequencing of nail units and DSP were combined to define cell type contributions of OM. We identified 173 genes upregulated in stromal compartments of OM compared to onychodermis, specialized nail mesenchyme. Gene ontology analysis of the upregulated genes suggested the role of Wnt pathway activation in OM pathogenesis. We also found PLA2G2A, a known modulator of Wnt signalling, is strongly and specifically expressed in the OM stroma. The potential role of Wnt pathway was further supported by strong nuclear localization of β-catenin in OM. Compared to the nail matrix epithelium, only a few genes were increased in OM epithelium. Deconvolution of nail unit cell types showed that onychofibroblasts are the dominant cell type in OM stroma. Altogether, integrated spatial and single-cell multi-omics concluded that OM is a tumour that derives a significant proportion of its origin from onychofibroblasts and is associated with upregulation of Wnt signals, which play a key role in the disease pathogenesis.

Leukonychia: What Can White Nails Tell Us?

Changes in nail color can provide important clues of underlying systemic and skin disease. In particular, white discoloration (leukonychia) has a high prevalence with a wide array of potential relevant causes, from simple manicure habits to life-threatening liver or kidney failure. Therefore, a reliable assessment of the patient with leukonychia is essential. In the past, two classifications for leukonychia have been presented. The morphological classifies the nail according to the distribution of the white lines: total, partial, transversal, and longitudinal leukonychia. Mees’ and Muehrcke’s lines are examples of transversal leukonychia, while Terry’s and Lindsay’s nails are examples of total and partial leukonychia. The anatomical classifies according to the structure responsible for the white color: the nail plate in true leukonychia, the nail bed in apparent leukonychia, and the surface only in pseudoleukonychia. In this review, both morphological and anatomical features have been combined in an algorithm that enables clinicians to approach leukonychia efficiently and effectively.

Pleomorphic Onychomatricoma: A Mimicker of Malignancy

Pleomorphic onychomatricoma is a rare condition mimicking malignant neoplasms. Given its rarity, the diagnostic and prognostic criteria of this condition are not well established. The aim of this study was to characterize a series of 6 cases of pleomorphic onychomatricoma. In 3 cases the submitting clinical diagnosis was subungual squamous cell carcinoma. For all 6 cases, nail clipping showed typical features of onychomatricoma as a free-edge thickening and pitting of the nail plate with an additional feature of projecting line pattern. Pleomorphic onychomatricoma was diagnosed based on moderate-severe cytological atypia, yet degenerative-appearing with multinucleation or smudged chromatin, no mitotic activity or necrosis, and a Ki67 proliferative index inferior to 5% overall. Other finding s included epithelioid multinucleated cells with deeply eosinophilic cytoplasm mimicking epithelioid malignant cells, overexpression of Ki67 and p53 on atypical cells and diffuse expression of p16. This study describes additional criteria in pleomorphic onychomatricoma, permitting a wider recognition in order to avoid inappropriate treatment.

Onychomatricoma with Onychomycosis: A Case Report and Review of the Literature

Onychomatricoma is a primary benign neoplasm of the nail matrix. Currently, a limited number of cases have been reported, so it is still considered a rare neoplasia. However, it is debatable if this condition is underdiagnosed and underreported. Onychomycosis is an important differential diagnosis of onychomatricoma, and sometimes, both these conditions may even coexist in the same nail. As the tumor grows, tissue microenvironment is more vulnerable to dermatophytes. Probably, the altered keratin appears to be susceptible to fungal invasion. Careful clinical assessment and dermoscopic evaluation help nailing the diagnosis. Usually, total nail avulsion is the preferred therapeutic approach when they coexist. Herein, we present a case of a middle-aged woman with onychomycosis and onychomatricoma affecting a single fingernail. The proposed therapy was oral terbinafine for 6 months followed by a conservative surgery. There were dramatic changes in dermoscopic features after fungal treatment, which, to our knowledge, have not been previously reported.

Proliferating Onychomatricoma. Clinical, Dermoscopical, and Pathologic Features of Onychomatricoma New Variant Resembling Onycholemmal/Squamous Cell Carcinoma

Proliferating onychomatricoma is a new challenging variant of onychomatricoma that can clinically and histologically mimic squamous cell carcinoma/onycholemmal carcinoma. This is a retrospective case series study of the clinicopathologic and dermoscopic features of 6 patients with a pathologic diagnosis of proliferating onychomatricoma, which was conducted in the dermatology and dermatopathology departments of 2 university hospitals and a private nail's dermatology consultation. The clinical, histological, and immunohistochemical features and follow-up of 6 patients with proliferating onychomatricoma were analyzed; we compare our finding with 6 cases of conventional onychomatricoma. The female-to-male ratio was 1:1 with involvement of fingers in 4 and toe in 2. Among the symptoms were verrucous lesion simulating squamous cell carcinoma, nail thickening, periungual erythema, and pain; symptom duration ranged from 5 to 8 years. Clinical, dermoscopical en face free-margin view, and nail-clipping histologic findings reveal a nail wall-like pattern with pitting. Intraoperative, noncontact, polarizing, light dermoscopy was available in 1 case and showed the typical signs of onychomatricoma (OM). Histologically, all cases showed a well-differentiated, infiltrative, squamous, proliferative lesion exhibiting a lobulated and cystic pattern of growth in the dermis. Abrupt keratinization reminiscent of trichilemmal keratinization, but corresponding in fact to keratogenous spheres, was noted as well as a dysmaturative epithelial pattern. No atypical cytomorphological changes were found. Proliferating onychomatricoma is a new variant of onychomatricoma, which can be misdiagnosed as squamous cell carcinoma/onycholemmal carcinoma; its proper recognition may minimize morbidity associated with inappropriate treatment. Proliferating OM can be differentiated from conventional OM clinically by a free-edge wall-like pattern and on histology of nail clipping by the relatively small size of the cavities. Dermoscopic and nail clipping attributes as free-edge honeycomb-like cavities associated with conventional OM are well established and permit a diagnosis of OM without an invasive nail biopsy. The free-edge wall-like pattern is a distinct new dermoscopic and nail-clipping pattern that should raise for the others onychogenic neoplasms and prompt the clinician to obtain a biopsy specimen. In addition to proliferating OM, the differential diagnosis includes a micropapilliferum variant of OM, onychocytic matricoma, and onychocytic carcinoma.

Onychomatricoma on the fourth toenail: A rare tumor in a rare localization

Onychomatricoma is a rare benign tumor of the nail matrix, characterized by finger-like projections that invade the nail plate. The fingernails of Caucasian women are most commonly affected. Because this tumor can easily mimic other more prevalent ungual diseases, it is crucial to be acquainted with its characteristic clinical and histopathologic features. The authors present a case of a 40-year-old man with an onychomatrichoma in the fourth left toenail, which was initially misdiagnosed and treated as onychomycosis.

Nail Tumors

This article describes nail tumors and their clinical features, biologic behavior, and treatment. Tumors included are onychopapilloma, onychomatricoma, periungual fibromas/fibrokeratomas, glomus tumors, subungual exostosis, myxoid cysts, and squamous cell carcinoma.

Dermoscopy of the Nail Unit

Nail dermoscopy (onychoscopy) is being used for a more accurate diagnosis of all nail disorders and has become a routine diagnostic instrument. In daily practice, nail signs can be magnified, and dermoscopy may confirm the clinical diagnosis and guides in management of nail diseases and treatments, permitting a better visualization of symptoms. Onychoscopy is used by the experts in almost all nail diseases. It can be performed dry or with ultrasound gel in order to make the stratum corneum translucent, depending on which part of the nail unit has to be evaluated.

Onychomatricoma Micropapilliferum, a New Variant of Onychomatricoma: Clinical, Dermoscopical, and Histological Correlations (Report of 4 Cases)

This is a report of a previously undescribed type of onychomatricoma (OM) with an unusual clinical presentation as a thickened free edge of the nail plate without discernible cavities and distinguished histologically from the ordinary OM by 3 features: (1) the lack of cavitation at the proximal border of the nail plate and the small sizes of the cavities at the free edge of the distal nail plate; (2) a papillated epithelial hyperplasia pattern very different from the digitate pattern of the ordinary OM; and (3) a special pattern of matrical keratinization with pseudohorn cysts that mirror closely those found in onychocytic matricoma (OCM). Furthermore, the sex ratio and sites of the lesion seem different than those of conventional OM with the caveat that the numbers in this series are small. A practical approach to the diagnosis of onychogenic tumor mainly involves consideration of tumors that clinically present as localized longitudinal pachyonychia including melanoma and Bowen disease. Whether pachyonychia is caused by a thickened nail plate or by a localized band of subungual hyperkeratosis may not be clinically and dermoscopically obvious, and leucoxanthonychia or melanonychia is observed in OCM, OM, and onychocytic carcinoma. Therefore, the definitive diagnosis of these 3 onychogenic tumors is made by histopathology on nail clipping specimen or nail biopsy. OM is easily diagnosed as a fibroepithelial tumor keeping in mind its micropapilliferum variant which can simulate trichoblastoma or basal cell carcinoma on biopsies without nail plate. In these biopsies, the fibroepithelial portion of OM micropapilleferum resembles trichoblastoma including trichoepithelioma, or keratotic basal cell carcinoma, whereas the pseudohorn cysts may be mistaken for seborrheic keratosis. As previously indicated in the seminal report of OCM and perfectly demonstrated in this series, the pseudohorn cysts of both OCM and OM micropapilleferum have 2 distinct layers with a ring pattern, the prekeratogenous and keratogenous zone, and the transitional eosinophilic onychocytes become progressively clear with shadow cells. By contrast, horn cysts with hyaline and trichilemmal keratinization have rounded or irregular shapes, a thin inner layer of eosinophilic cells with large, oval, pale, vesicular nuclei, and are filled with compact keratinous masses without transition to onychocytic shadow cells. The squamous eddies of irritated seborrheic keratosis are easily differentiated from the pseudohorn cysts of OM by their inner layer of eosinophilic flattened squamous cells, and their loose or compact eosinophilic keratinous masses without transition to onychocytic shadow cells. To avoid confusion with the pseudohorn cysts of seborrheic keratosis which present a thin granular layer and laminated cornified cells, we propose to designate the pseudohorn cysts of both OM and OCM as keratogenous spheres. The papillae of the latter end as a tip without keratogenous zone explaining the microcavities. The microcavities getting in touch with the surface of the nail plate are responsible for the white dots (the so-called milia cysts) observed by dermoscopy both in OCM and OM micropapilliferum. The low, projecting ridges separated by the irregular longitudinal furrows explain the clinically irregular white line. The evenly thickened free edge of the distal nail plate is explained either by the small size of the cavities or the presence of a keratogenous zone at the tip of the papillae which manufacture a homogeneous thick nail plate. This free edge nail wall-like pattern (with or without a pitted wall) is in stark contrast to the usual honeycomb-like cavity pattern seen in conventional OM. It is inferred that these dermatoscopic findings could be clinical clues to differentiate both OCM and OM micropapilliferum from conventional OM. In the initial description of OCM, this entity was clearly differentiated from seborrheic keratosis. From time to time, these 2 lesions continue to pose problems in the histological differential diagnosis, and OCM with its various clinical presentations as leucoxanthonychia or melanonychia has been described using different names as subungual seborrheic keratosis, nail unit acanthoma, or longitudinal subungual acanthoma. These new superfluous synonymies add confusion in nail tumors. In the estimation of the author, these so-called new entities are OCM, if the histologic criteria of keratogenous spheres defined in this article are used. In sum, there are 2 clinicopathological variants of OM: macropapilliferum and micropapillerum. As OM micropapillerum has small cavities, the main differential diagnosis on nail clipping is onychocytic carcinoma.

Intraoperative dermoscopy features of subungual squamous cell carcinoma: a study of 53 cases

BACKGROUND

Subungual squamous cell carcinoma (SU-SCC) is the most common malignant tumour of the nail unit. Intraoperative nail dermoscopy has been described only for pigmented tumours, onychomatricoma and glomus tumours.

AIM

To establish a description of intraoperative dermoscopic features of SU-SCC.

METHODS

A single-centre retrospective cohort of 53 SU-SCC cases over a 5-year period was reviewed by six examiners who individually scored 31 intraoperative dermoscopic features as present or absent. For each feature, the frequency and interobserver agreement was evaluated, then the data were compared and a consensus was reached.

RESULTS

No feature had perfect or substantial interobserver agreement. Regarding anatomy and architecture, most tumours involved both the nail bed and nail matrix (n = 34, 64.2%) and had nonparallel lateral side edges (n = 36, 67.9%). Regarding vascular features, several different patterns were found: dotted vessels (n = 49, 92.5%), irregular vessels (n = 47, 88.7%), curved vessels (n = 46, 86.8%), sagittal vessels (n = 45, 84.9%), milky-red areas (n = 42, 79.2%), linear and regular vessels (n = 30, 56.6%), coiled and hairpin vessels (n = 23, 43.4%), and arborizing vessels (n = 16, 30.2%). Pigmented dermoscopy structures included dotted purpura, grey granulation and splinter haemorrhages, which were found in 49 (20.8%), 9 (17%) and 9 (17%) cases, respectively. Other dermoscopic signs were pink background, translucent structureless area, whitish scaly areas, distal plug, yellowish scales and dots, and 'digitiform' proximal edge, which were found in 49 (84.9%), 49 (84.9%), 43 (81.1%), 37 (69.8%), 28 (52.8%) and 22 (41.5%) cases, respectively.

CONCLUSION

Analysis of this first large series of SU-SCC studied by intraoperative dermoscopy suggests that it gives useful information to better approach the diagnosis and to target biopsies.

Onychomatricoma Presenting as a Dystrophic Right Great Toenail: Case Report and Review

Onychomatricoma is a rare, benign nail matrix tumor. It most frequently occurs on one of the first three fingers of the dominant hand or the big toe in middle-aged women. Our patient presented with a 10-year history of a progressive thickening of her right great toenail; it bled easily and was intermittently painful. She had experienced trauma to the nail prior to the onset of the dystrophy. MRI primarily showed inflammation localized to the nail bed without bony extension. Excisional biopsy, which included both the nail plate and matrix, established the diagnosis of onychomatricoma originating from the ventral nail matrix (lunula). Nail trauma or fungal infection may have a causative role in the pathogenesis of onychomatricoma. The nail plate can show splitting, increased curvature, or ridging; it can also present with yellow, red or brown, linear, pigmented bands. The clinical differential diagnosis of onychomatricoma includes fibrokeratoma, melanonychia, onychomycosis, periungual fibroma, and squamous cell carcinoma. Dermoscopic imaging shows parallel lesion edges and splinter hemorrhages; these dermoscopic features support the diagnosis of onychomatricoma over squamous cell carcinoma. Imaging such as ultrasound or MRI may suggest the diagnosis. Biopsy of the tumor is necessary to establish the diagnosis; the tumor may derive either from the ventral nail matrix (lunula) or from the ventral surface of the proximal nail fold. Histologic features vary depending not only on tumor origin but also on tissue orientation. Proximally, there is a fibroepithelial tumor consisting of fibrous stalk pierced by epithelial invaginations; the epithelium shows matrical differentiation containing basal and prekeratogenous cells. Distally, the tumor pierces the nail plate as glove-finger digitations; these digitations appear as discrete villi in the nail plate or show their negative image as multiple empty channels that have been described as “worm holes”. The channels may be epithelial lined and contain serous fluid. It is important to obtain an adequate biopsy specimen; the distinctive fibroepithelial histology might be inapparent in partial specimens lacking the epithelial invaginations. Immunohistochemical staining can distinguish onychomatricoma from tumors that can mimic its pathologic changes: fibromyxoma, neurofibroma, and perineurioma. Complete surgical excision is generally curative.

Myxoid Onychomatricoma-A New Case

Onychomatricoma is a slow-growing, benign neoplasm of the nail matrix with several histological variants. With only 2 cases previously reported, the term "myxoid onychomatricoma" has been used by some authors to describe a rare variant, known to have a fibromixoid component. We present a case of a 51-year-old Caucasian woman with a 1-year history of thickening and discoloration of the right thumbnail, who was initially misdiagnosed as onychomycosis. After performing a magnetic resonance imaging that showed a tumor with several filamentous projections, an onychomatricoma was suspected and a total distal plaque avulsion was performed. Histology revealed a biphasic tumor with an epithelial component and a prominent myxoid stroma. Immunohistochemical staining was then used, confirming the diagnosis. Considering these findings, we believe that our case meets the diagnostic description of "myxoid onychomatricoma" and is, therefore, a new case of this rare histological variant.

Onychoscopy with red light for vascular pattern identification: a study of 33 patients

BACKGROUND

Nail dermoscopy (onychoscopy) during physical examination assists in correct diagnosis. Often further magnifications are necessary for an effective differential diagnosis. With the addition of a red light to the dermoscope, important vascular features can be visualized.

OBJECTIVE

To describe common features observed at onychoscopy with a new device that combines the regular white light with the red light illumination, demonstrating that it is useful for diagnosis of nail disorders.

METHODS

We enrolled 33 consecutive patients referred to the Nail Diseases Dermatology Unit of the University of Modena and Reggio Emilia and to the Outpatient Consultation for Nail Disease of the Dermatology Unit of the University of Bologna. Patients were assessed with a standard hand-held dermoscope and at the red light dermoscope. Dermoscopic images were collected.

RESULTS

The new prototype was used during daily clinical practice and allowed a more accurate visualization of some details that classic onychoscopy can miss. In particular, with the help of the red light it was possible to better visualize nail lesions that were characterized by some kind of colour change or vascular alterations.

CONCLUSION

The new device of red light for vascular pattern onychoscopy can be a new investigation method to observe nail alterations, especially due to vascular pattern, even with low magnification, without the necessity to use higher resolutions.

Squamous cell carcinoma of the nail unit

Squamous cell carcinoma (SCC) of the nail apparatus is a rare malignant tumor that usually originates underneath the nail plate and grows slowly with possible bone invasion. The etiology remains unknown, although a strong association with different conditions, such as high-risk human papillomavirus (HPVs), trauma, or radiation exposure has been demonstrated. Nail SCC is called "the great mimicker nail tumor" because different clinical presentations may coexist, resembling benign or malignant nail lesions. For this reason, there is often a significant delay between the onset of nail SCC and the diagnosis. Clinical manifestation includes onycholysis and erythema, while in the advanced stages nail ulceration can be observed. The association with pain, swelling, and inflammation usually indicates an invasive SCC with involvement of the underlying bone. Metastasis is rare but possible with involvement of lymph nodes. A multidisciplinary approach to assessment, management, and follow-up is advised. Using careful examination and modern diagnostic methods, including onychoscopy, biopsy, and histopathology, will help identify SCC and prevent the invasive progression. X-ray is important to investigate the bone invasion to determine the best surgical approach that will have satisfying cosmetic and functional outcomes. Nevertheless, local excision with sufficient surgical margins, best if using Mohs surgery, is usually sufficient and superior to amputation of the distal phalanx. This review aims to highlight the correct approach in suspected SCC of the nail unit.

Alternative uses of dermoscopy in daily clinical practice: An update

Dermoscopy is a noninvasive diagnostic tool that is currently being used for neoplastic skin lesions, several inflammatory and infectious diseases, and skin appendage disorders. As the clinical applications of dermoscopy beyond pigmented lesions are constantly increasing, the aim of this article is to provide an update on this topic. This comprehensive review substantiates how several diseases may show peculiar dermoscopy features so as to enhance the diagnosis and avoid (in selected cases) unnecessary histologic confirmation. In other cases, dermoscopy features may be shared with other conditions, with the advantage of narrowing down the differential diagnosis by ruling out those dermatoses with similar clinical aspect but different dermoscopic presentation.

Pigmented onychomatricoma: Four cases

Onychomatricoma (OM) presenting as a longitudinal melanonychia is a very uncommon clinical presentation with very few cases in the literature. Our aim in this article is to report four cases of pigmented OM, and describe their clinical and dermoscopic findings and the importance of the differential diagnoses, especially with melanoma.

Dermoscopy in the Evaluation of Nail Disorders

Nail dermoscopy was initially used only in the assessment of nail pigmentation, but now it is widely utilized for the evaluation of many nail disorders. In daily practice, dermoscopy may confirm clinical diagnoses and guides in the management of nail diseases and treatments, permitting a better visualization of symptoms. Dry dermoscopy is required for evaluation of the nail plate surface, while gel as an interface is necessary for assessment of nail pigmentation and onycholysis, as well as for the evaluation of the distal nail margin. In this review, we describe the dermoscopic features of the most important nail disorders, looking at the different areas of the nail. Dermatoscopic changes that usually accompany specific nail diseases are also reviewed.

Nail neoplasms

Nail neoplasms include all tumors occurring in the nail or periungual apparatus tissue. While some nail tumors can be similar to tumors located on the skin, others are unique. Both benign and malignant lesions can affect the nail apparatus. In particular, early malignant tumors like melanoma and squamous cell carcinoma can present similarly to onychomycosis or benign melanonychia and frequently missed by clinicians. Therefore, physicians should be aware of nail structures and the characteristics of nail tumors. Our review covers the normal nail structure and the most common nail tumors from benign to malignant.

Giant Onychomatricoma of the Great Toenail: Case Report and Review Focusing on Less Common Variants

Onychomatricoma is a rare benign fibroepithelial filamentous tumor originating from the nail matrix. It typically presents with the clinical tetrad of xanthonychia, pachyonychia, proximal splinter hemorrhages and increased transverse overcurvature of the nail plate. The giant variant can easily confuse the clinician due to its extensive nail dystrophy that can mask the characteristic features of this tumor. Benign (fibrokeratoma, ungual fibroma, onycholytic matricoma) and malignant entities (Bowen's disease, squamous cell carcinoma, onycholytic carcinoma) are mimics of the disease. Nail surgery can facilitate the diagnosis, which should always be confirmed by histology, as rare variants do exist.

Onychomycosis and Onychomatricoma

Nail dermoscopy is helpful in the differential diagnosis of nail disorders including onychomycosis and pigmented and nonpigmented nail tumors. We report two cases of onychomatricoma with concurrent onychomycosis of the same digit. In both cases, dermoscopy of the nail plate exhibited features of onychomatricoma, whereas dermoscopy of the distal free edge revealed features of onychomycosis. It is not uncommon for patients with onychomatricoma to develop coexisting onychomycosis, as channels created by the tumor render the nail plate susceptible to invasion by fungi.