Clinical and Histopathologic Features of Subungual Melanoma in 57 Mexican Patients: A 5-Year Cohort Study. / Características clínicas e histopatológicas de melanoma subungueal en 57 pacientes mexicanos: una cohorte de 5 años.

Although subungual melanoma is uncommon, it is associated with worse outcomes than melanomas in other locations and accounts for 1% to 23% of all melanomas, depending on the population. The aim of this study was to describe the clinical and histopathologic features of subungual melanoma in a Mexican population. We identified 303 patients with melanoma, and of these, 19% (57 patients with a median age of 71 years) had subungual melanoma. The main sites affected were the lower limbs (52.6%) and the toe (75.4%). The most common histologic subtype was acral lentiginous melanoma (50.9%). Median Breslow thickness was 3 mm, and stage IA tumors were the most common (in 28.1% of patients). Recurrence and metastasis occurred in 19.3% and 8.8% of patients, respectively. The clinical and histopathologic features identified are similar to those described in the literature. Early diagnosis and treatment are crucial for improving prognosis.

Frontal Examination of the Distal Nail Unit. / Visión frontal distal de la uña.

Clinical findings in many nail disorders are not usually pathognomonic. An accurate diagnosis therefore relies on inspection of the nail unit from different angles. We review clinical features of different nail disorders that can be observed during frontal examination of the distal edge of the nail plate and the hyponychium and correlate these with features observed when the nail is viewed from above. Frontal examination of the distal nail unit can help establish a clinical diagnosis in routine practice.

[Translated article] Frontal Examination of the Distal Nail Unit.

Clinical findings in many nail disorders are not usually pathognomonic. An accurate diagnosis therefore relies on inspection of the nail unit from different angles. We review clinical features of different nail disorders that can be observed during frontal examination of the distal edge of the nail plate and the hyponychium and correlate these with features observed when the nail is viewed from above. Frontal examination of the distal nail unit can help establish a clinical diagnosis in routine practice.

[Translated article] Clinical and Histopathologic Features of Subungual Melanoma in 57 Mexican Patients: A 5-Year Cohort Study.

Although subungual melanoma is uncommon, it is associated with worse outcomes than melanomas in other locations and accounts for 1% to 23% of all melanomas, depending on the population. The aim of this study was to describe the clinical and histopathologic features of subungual melanoma in a Mexican population. We identified 303 patients with melanoma, and of these, 19% (57 patients with a median age of 71 years) had subungual melanoma. The main sites affected were the lower limbs (52.6%) and the toe (75.4%). The most common histologic subtype was acral lentiginous melanoma (50.9%). Median Breslow thickness was 3 mm, and stage IA tumors were the most common (in 28.1% of patients). Recurrence and metastasis occurred in 19.3% and 8.8% of patients, respectively. The clinical and histopathologic features identified are similar to those described in the literature. Early diagnosis and treatment are crucial for improving prognosis.

Tumor invasion in the hyponychium is associated with distant metastasis and poor prognosis in subungual melanoma: A histologic landscape of 44 cases.

BACKGROUND: Subungual melanoma (SUM) has a poor prognosis because of delayed diagnosis. Its progression, consensus on surgical treatment, and correlation with clinical outcomes remain unclear. OBJECTIVE: We aimed to identify the pattern of dermal invasion in different locations of the nail apparatus and its relationship with prognosis. METHODS: In this retrospective review of surgically treated SUM patients between January 2011 and April 2019, the nail apparatus was divided into 5 anatomic subunits: the dorsal roof of proximal nail fold, ventral floor of proximal nail fold, germinal matrix, nail bed, and hyponychium. Invasions in the subunits were categorized using 3 criteria: no tumor, in situ tumor, or invasion. RESULTS: Among 44 cases of SUM, dermal invasion occurred mostly in the distal areas, with 11, 30, 18, 7, and 4 in the hyponychium, nail bed, germinal matrix, ventral floor of proximal nail fold, and dorsal roof of proximal nail fold, respectively. The patients with hyponychial invasion showed a significantly greater Breslow depth (P = .009), a higher rate of lymph node metastasis (P = .019), distant metastasis (P = .036), and shorter disease-free survival (P = .001). CONCLUSION: Hyponychial invasion is an important prognostic predictor of SUM, given its strong association with invasion depth, metastatic progression, and disease-free survival. Patients with invasion in the hyponychium should undergo more strict workup, treatment, and surveillance.

Distal nail embedding treatment using autogenous nails.

A regrowing nail tip after nail avulsion may excessively curve and invaginate into the nail bed. This is treated as a type of ingrown toenail, and is known as distal nail embedding. In most cases, further growth restores the original shape evenly over the nail bed. However, it is often painful and such cases may require treatment. We report a surgical approach that we applied to six cases of distal nail embedding involving pain or deformity of nails caused by a nail tip invaginating into the nail bed and/or cessation of forward nail growth. As our method involves removing a portion of the embedded tip edge nail and inserting the removed nail into the remaining depressed portion, the nail can grow over the bulge. In all six patients in whom we applied this method, the pain and nail deformity resolved and there was no recurrence. We used autogenous nails, which can reduce the pressure imbalance on a nail bed, and this contributed to improving the morphology of nails and nail beds. In addition, the risk of a hypertrophied nail is reduced because half of the nail adheres to the nail bed. Special materials are unnecessary and this method can be conducted with simple outpatient department procedures. There were no cases of a fixed nail section detaching due to a bulge at the nail tip. The inserted nail was maintained in all cases for several months until the nail grew over the bulge.

Iontophoresis for drug delivery into the nail apparatus: exploring hyponychium as the site of delivery.

In present studies, a hyponychium pathway (from ventral side of the nail plate) was investigated as a potential route of drug delivery into the nail apparatus using iontophoresis as an active physical method. In vitro transport studies were performed across the human nail plate using sodium fluorescein as a marker substrate for 24 h. After transport studies, the amount of sodium fluorescein extracted from an active diffusion area of the nail plate in case of iontophoresis was found to be ∼54-folds more to that of passive. The amount of sodium fluorescein retained in the peripheral area of the nail plate after application of iontophoresis was found to be ∼30-folds more relative to passive. Ex vivo transport studies were performed on excised human cadaver toe using terbinafine hydrochloride as a model drug for three days (8 h/day). The amount of terbinafine retained in the nail plate after application of iontophoresis (3.43 ± 1.34 µg/mg) was ∼20-folds more when compared with passive (0.17 ± 0.10 µg/mg). The amount of drug extracted from the nail bed and nail matrix was 1.73 ± 0.12 µg/mg and 0.55 ± 0.22 µg/mg, respectively. On the other hand, there was no detectable amount of terbinafine found in the nail bed and nail matrix in case of control (passive delivery). These studies show that the iontophoretic drug delivery through hyponychium region to other parts of the nail apparatus could be a potential way of onychomycosis treatment.

Anatomy of the nail unit and the nail biopsy.

The nail unit is the largest and a rather complex skin appendage. It is located on the dorsal aspect of the tips of fingers and toes and has important protective and sensory functions. Development begins in utero between weeks 7 and 8 and is fully formed at birth. For its correct development, a great number of signals are necessary. Anatomically, it consists of 4 epithelial components: the matrix that forms the nail plate; the nail bed that firmly attaches the plate to the distal phalanx; the hyponychium that forms a natural barrier at the physiological point of separation of the nail from the bed; and the eponychium that represents the undersurface of the proximal nail fold which is responsible for the formation of the cuticle. The connective tissue components of the matrix and nail bed dermis are located between the corresponding epithelia and the bone of the distal phalanx. Characteristics of the connective tissue include: a morphogenetic potency for the regeneration of their epithelia; the lateral and proximal nail folds form a distally open frame for the growing nail; and the tip of the digit has rich sensible and sensory innervation. The blood supply is provided by the paired volar and dorsal digital arteries. Veins and lymphatic vessels are less well defined. The microscopic anatomy varies from nail subregion to subregion. Several different biopsy techniques are available for the histopathological evaluation of nail alterations.

Physiology of the nail apparatus: Surgical consequences.

Knowledge of nail physiology is mandatory to understand nail pathologies, and to know what to repair and what to expect from your repair. Unfortunately, nail physiology in humans is not completely understood. However, there are some data that have been validated and must be known before treating patients. The nail plate is mostly made of keratins. It is produced solely by the nail matrix. The nail bed is mostly responsible for nail pate adhesion. At the hyponychium, the plate loses its adherence. The hyponychium is the first barrier of defense preventing bacteria and fungi from invading the subungual area. All these structures, along with the nail folds, are responsible for the orientation of nail-plate growth. However, many questions, such as whether to replace the nail plate at end of procedure, remain open.

[Nerve sheath myxoma of the hyponychium]. / Myxome des gaines nerveuses de l'hyponychium.

BACKGROUND: Nerve sheath myxoma is a rare benign tumour of the extremities that was long confounded with neurothekeoma. Herein, we describe a rare case of interest because of its site on the hyponychium. PATIENTS AND METHODS: A 31-year-old woman presented with a painless distal tumour on the right ring finger that had been present for 3 to 4 years. It consisted of a firm, round nodule under the nail and spreading to the fingertip. Complete excision was carried out after cutting away the distal nail plate. Histological examination revealed a myxoid tumour comprising very clearly delineated lobules containing pale fusiform cells with small nuclear inclusions. These cells expressed S100 protein but no CD34 or epithelial membrane antigen (EMA). Complete excision was performed and a full recovery was made. DISCUSSION: This type of tumour is characteristic of nerve sheath myxoma, and is almost certainly of Schwannian origin, although distinct from Schwannoma. It is rare, occurs after the age of 35 years and is preferentially located in the extremities of the limbs. There has only been one other description of its occurrence under the fingernail, in which it was described as neurothekeoma. However, neurothekeoma is entirely different, being more cellular, with no expression of protein S100, and marked by the NKIC3 antibody; it occurs in children or young adults, and is frequently found on the face. These two tumours were confused for some time, but today they must be completely distinguished from one another. These myxomas must be completely excised because of the risk of relapse. Finally, they should be distinguished from other myxoid tumours of the digits, certain of which can be malignant.

Acral Fibrochondromyxoid Tumor Presenting as Enlarging Nodule Involving the Distal Fingertip and Hyponychium: A Case Report.

An acral fibrochondromyxoid tumor is a newly described type of benign soft tissue neoplasm that presents as a single nodular lesion on a finger or toe. There has only been one previous report on this tumor, a case series that described the initial pathologic and clinical findings; however, details on clinical history, physical examination, and outcome are unknown. In this report, we describe a case of a 39-year-old male who presented with a painful enlarging mass involving the distal right 3rd finger and hyponychium. Punch biopsy was performed and the lesion was identified as an acral fibrochondromyxoid tumor on microscopic examination. X-ray showed no bony involvement. The tumor was successfully excised with complete resolution of pain symptoms. We discuss the clinical features and immunohistochemistry findings of our case in the context of the current limited knowledge about this very rare tumor.

Efficacy of a tip of the big toe remodeling in the distal nail embedding with bone overgrowth of the distal phalanx.

INTRODUCTION: Distal nail embedding due to hyponychium hypertrophy can be caused by traumatic or surgical avulsion of the nail. As a consequence of these changes, the nail plate is blocked through the deformed tip of the toe. Changes that occur at the tip of the big toe are due to bone growth on the dorsal surface of the distal end of the distal phalanx. This study aimed to present a surgical technique for the treatment of hypertrophy of the tip of the toe and evaluate its effectiveness. MATERIAL AND METHODS: The surgical technique involved remodeling of the tip of the big toe, with removal of the hypertrophied bone of the distal phalanx. The procedure was assessed by using a questionnaire. RESULTS: We included the 108 distal embedded nails. A total of 85% of respondents were satisfied with the procedure. Nearly 80% of patients rated the cosmetic effect as good or very good. CONCLUSIONS: The technique was an effective treatment and increased the quality of life of those with disorders of nail growth associated with hypertrophy of the tip and hyponychium, with bone overgrowth.

Preservation of the Sterile Matrix, Hyponychium, and Fingertip Pad in Fingertip Reconstruction With Composite Fingertip and Nail Bed Graft and Volar V-Y Advancement Flap.

Background: The goals of fingertip reconstruction are to achieve adequate soft-tissue coverage and a functional nail plate and to maintain sensation, proprioception, and cosmesis. Objective: We present a composite tissue graft and volar V-Y advancement flap for reconstruction of a traumatic amputation of a fingertip, which provided optimal preservation of the hyponychium and the volar pad for prevention of a hook nail. Historically, composite fingertip grafts have not been recommended for adults with large defects. Methods: The amputated nail bed, hyponychium, and a 10 × 20-mm segment of the fingertip were utilized as a composite graft for reconstruction of the nail bed in an adult. The addition of a volar V-Y advancement flap to reconstruct the fingertip was necessary for complete soft-tissue reconstruction. Results: The reconstruction resulted in nail plate adhesion without significant nail deformity and a functional and sensate fingertip. Conclusion: Components of amputated fingertips including the sterile matrix, hyponychium, and part of the fingertip can be utilized in a composite graft to yield satisfactory functional and cosmetic results in adults.

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.

Diagnosis using the nail bed and hyponychium.

"Nails protect the fingertips and toes. Diseases affecting the nail can cause cosmetic disfigurement and social embarrassment. Physical functioning may be impaired. Disorders of the nail bed may cause pain or create difficulty grasping fine objects. The nail bed is the area beneath the nail plate between the lunula and the hyponychium. Disorders of the nail bed can cause onycholysis, subungual hyperkeratosis, and/or onychogryphosis. Ventral pterygium is less common. Tumors of the nail bed are rare and commonly missed."