Faculty Bibliography

Nail unit melanoma (NUM) is an uncommon form of melanoma and is often diagnosed at later stages. Approximately two-thirds of NUMs are present clinically as longitudinal melanonychia, but longitudinal melanonychia has a broad differential diagnosis. Clinical examination and dermoscopy are valuable for identifying nail findings concerning malignancy, but a biopsy with histopathology is necessary to confirm a diagnosis of NUM. Surgical treatment options for NUM include en bloc excision, digit amputation, and Mohs micrographic surgery. Newer treatments for advanced NUM include targeted and immune systemic therapies. NUM in pediatric patients is extremely rare and diagnosis is challenging since both qualitative and quantitative parameters have only been studied in adults. There is currently no consensus on management in children; for less concerning melanonychia, some physicians recommend close follow-up. However, some dermatologists argue that the "wait and see" approach can cause delayed diagnosis. This article serves to enhance the familiarity of NUM by highlighting its etiology, clinical presentations, diagnosis, and treatment options in both adults and children.

We call on dermatologists and dermatopathologists to include nail clipping histopathology as an essential component of the routine evaluation of melanonychia. This manuscript demonstrates a case where an adult woman with broad melanonychia of the right thumbnail declined a nail matrix biopsy, but was amenable to a nail clipping.The nail clipping showed pigmentation, melanocyte remnants, and small cavities in the nail plate. These features have been published previously by our group as a clue to nail unit melanoma within nail clippings.This patient was rapidly triaged for nail matrix biopsy, which demonstrated nail unit melanoma in situ. Every patient with melanonychia can benefit from a nail clipping by examination of the location of the pigmentation within the nail plate for surgical planning, and if melanocyte remnants are detected, the nail clipping also serves as a rapid triage mechanism for nail matrix biopsy to evaluate for nail unit melanoma. Fontana-stained sections will highlight the pigmentation in the nail plate, and its location in the nail plate can easily be described by the dermatopathologist. Nail clippings performed in the setting of clinically apparent melanonychia may show helpful histopathologic findings of pigmented fungi, hemorrhage, external pigmentation, features of other pigmented nail unit tumors, as well as other entities. Nail clipping histopathology can provide extensive information in the evaluation of melanonychia with minimal discomfort for a patient, and little disruption to a physician's clinic flow. With this additional case of a nail unit melanoma diagnosed after initial concern found in a nail clipping, as well as other information in the literature, it is clear that melanocyte remnants found in nail clippings are reliable concerning features related to nail unit melanoma in adults. With knowledge of these histopathologic features in nail clippings and the significance of melanocyte remnants, the dermatopathologist can play a crucial role in the use of a nail clipping as a life-saving diagnostic maneuver. Accordingly, given the potential benefit to patients in this setting, as well as other uses of a nail clipping in the evaluation of melanonychia, we call on dermatologists and dermatopathologists to innovate the routine evaluation of melanonychia through the routine employment of nail clippings for histopathologic evaluation.

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.

A 26-year-old male presented with a 2-year history of a hyperkeratotic growth from the left index finger. Histopathology was consistent with an acquired digital fibrokeratoma with changes of a pleomorphic fibroma. Lesional cells were negative for CD34, Rb, and p53, and were positive for FXIIIa. We introduce the pleomorphic acquired digital fibrokeratoma as a novel clinicopathologic entity.

Infantile digital fibromatosis (IDF), or inclusion body fibromatosis, is a rare benign tumor that commonly presents as a solitary nodule composed of spindle cells within the dermis on the digits of infants and children. Evaluation often includes a biopsy and typical therapies include observation, intralesional corticosteroid injections, and complete surgical resection. Given the rarity of IDF, few clinicians have direct or extensive experience diagnosing or treating it. Here we present a comprehensive review of the presentation, diagnosis, and treatment for IDF.