Successful treatment of onychomatricoma with minimally invasive surgical procedures based on its pathogenesis: A case report.

Onychomatricoma is a rare, fibroepithelial tumor of the nail. Although it is benign, unnecessary and excessive treatment, such as extensive or total removal of the nail matrix, has been reported in the past. Recently, it was speculated that onychomatricoma is derived from onychomatricodermis, the dermal stroma of the nail matrix. Excision of the stromal rather than the epithelial component of the tumor is important. However, since the boundary between the normal and diseased stroma is usually unclear, minimal excision at the base of the tumor projection should be sufficient. We report a case of onychomatricoma and suggest a method of surgical treatment that would minimize postoperative deformity of the nail plate.

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.

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.

An Uncommon Cause of Pincer Nail.

Pincer nail is a deformity characterized by excessive transverse curvature of nail, progressively increasing along its longitudinal axis. The curvature is greatest at the distal end, leading to an ingrown nail, producing pain, discomfort, and significant cosmetic alteration. It is a severe variant of ingrown nail, often attributed to causes such as anatomical variation of nail plate axis, tight footwear, gait abnormalities, and so on. Correspondingly, its management involves the removal of the lateral ingrowing nail plate or the lateral hypertrophic nail folds. We report a young male who presented with symptomatic pincer nail deformity. However, on exploration there was a midline onychomatricoma, leading to the thickening of the central part of the nail plate, causing incurving of the lateral nail plate and discomfort. The report serves to highlight the need for a comprehensive evaluation of pincer nails, to assess for matrix disease as well, because the surgical approach will differ accordingly.

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.

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 ß-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.

Onicomatricoma: puntos clínicos claves de una enfermedad infrecuente / Onychomatricoma: Key clinical points of an unfrequented disease

Resumen Introducción: el onicomatricoma es un tumor fibroepitelial originado en la matriz ungular, es infrecuente y suele presentarse alrededor de la quinta y sexta década de la vida. Métodos: se presenta el caso de un paciente masculino de 57 años, sin antecedentes patológicos, quien consultó por una lesión no dolorosa en la uña del tercer dedo de la mano derecha. Al examen físico presentaba cromoniquia amarilla longitudinal, estrías blanquecinas y hemorragias en astilla. Se realizó onicectomía y matricectomía proximal y se envió el especimen resecado a estudio histopatológico. Resultados: el examen histopatológico reportó una lesión fibroepitelial, con invaginaciones del epitelio y ausencia de la capa granulosa. En el estroma se observaban células ondulantes y fusocelulares acompañadas de mastocitos. Se realizaron tinciones de inmunohistoquímica, confirmando el diagnóstico de onicomatricoma, variante micropapilifera. Conclusiones: debido a los múltiples diagnósticos diferenciales de esta condición, es importante para el dermatólogo familiarizarse con la clínica, hallazgos dermatoscópicos y manejo de esta entidad.

Abstract Introduction: onychomatricoma is a fibroepithelial tumor originating in the nail matrix, it is infrequent and usually presents around the fifth and sixth decades of life. Methods: we present the case of a 57-year-old male patient, without relevant past medical history, who complained of a non-painful lesion in the nail of the third finger of the right hand. Physical exam revealed longitudinal yellow chromonychia, whitish striae, and splinter hemorrhages. Onychectomy and proximal matricectomy were performed and the resected specimen was sent for histopathological study. Results: the histopathological study reported a fibroepithelial lesion, with invaginations of the epithelium and absence of the granular layer. Undulating and spindle cell cells accompanied by mast cells were observed in the stroma. Immunohistochemical staining was performed, confirming the diagnosis of onychomatricoma, micropapiliferum variant. Conclusions: due to the multiple differential diagnoses of this condition, it´s important for the dermatologist to become familiar with the clinic, dermoscopic findings and management of this entity.

A 'sea anemone' onychomatricoma.

OBJECTIVE: Here we describe the presentation, identification, operation details and subsequent histological analysis of an onychomatricoma, a benign rare subungual tumour that is often misidentified and diagnosed. METHODS: No public involvement to declare, patient was consented for surgical excision and provided verbal consent to photography and its use in publishing. PARTICIPANT: One 44-year-old female. INTERVENTION: One time surgical excision. PRIMARY AND SECONDARY OUTCOMES MEASURED: Not applicable. RESULTS: Complete excision and histopathological report of specimen provided. CONCLUSION: Complete surgical excision is an effective means of treatment for onychomatricoma.

Several rare nail unit tumors / 中华皮肤科杂志

Nail unit tumors are a group of rare tumors only occurring in the nail unit, including onychopapilloma, onychomatricoma, onychocytic matricoma, onycholemmal carcinoma, and so on. These tumors have specific clinical manifestations and pathological features due to their special anatomical locations. This review focuses on clinical manifestations, histopathological characteristics and treatment of the above tumors.

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.

Pigmented onychomatricoma may originate from a childhood trauma: A case report.

Pigmented onychomatricoma (OM) is a very rare benign fibroepithelial tumor of the nail matrix. We report the case of a 23-year-old Lebanese man with 15-year history of nail plate dystrophy with longitudinal ridging, yellowish discoloration, excessive transverse curvature and late-onset melanonychia along the medial third of the right thumb nail. Excisional biopsy was performed and confirmed OM. We outline the clinical history, radiological and histopathological findings as well as the surgical and reconstructive technique of this unusual case of OM. The age group, history of crush injury, and pigmentation of the nail plate make of this rare form of ungual tumor an interesting case report.

Magnetic Resonance Imaging in the Diagnosis of Onychomatricoma: A Case Report.

Onychomatricoma (OM) is a rare benign tumour of the nail matrix characterized by specific clinical and histologic features. The main clinical signs are thickening of the nail plate, xanthonychia, overcurvature of the nail plate, and multiple splinter haemorrhages. The diagnosis is based on clinical, radiological and histopathological findings. Histologically, the tumour is characterized by filiform epithelial projections. The objective of this study is to present the first reported Tunisian case of OM, focusing on the contribution of magnetic resonance imaging to the diagnosis of OM. A review on the subject is also presented.