Faculty Bibliography

BACKGROUND:Yellow nail syndrome (YNS) is a rare syndrome with unknown pathogenesis characterized by a clinical triad of respiratory disease, lymphedema, and xanthonychia. Diagnosis is challenging as clinical manifestations often do not occur concurrently. Due to disease rarity, few studies to date have characterized YNS or assessed therapeutics. OBJECTIVE:We aimed to characterize clinical findings of YNS and compare therapeutic regimens to provide diagnostic and management recommendations. METHODS:An international multi-institutional retrospective cohort study of YNS patients was conducted by a panel of nail experts. RESULTS:We included 111 YNS patients. Xanthonychia, increased transverse curvature, thickening, nail growth arrest, and a history of respiratory disease or lymphedema was highly suggestive of YNS. The therapeutic regimen with highest complete response rate was oral vitamin E combined with oral azole antifungals. LIMITATIONS/CONCLUSIONS:Limitations include non-randomized and retrospective design. Clinical details were inconsistently reported. Some treatments discussed are expert opinions and based on hypothetical and/or minimal data. CONCLUSION/CONCLUSIONS:We provide the largest study to date characterizing YNS. We suggest that patients with suspected YNS undergo mycologic examination and referral to pulmonology. We recommend oral vitamin E with oral azole antifungal as first line therapy for YNS. Reassurance/no treatment could also be considered.

INTRODUCTION/UNASSIGNED:Angiokeratomas are benign vascular tumors that typically present as a hyperkeratotic, red-brown to black papule on the lower extremities. Angiokeratomas in the subungual location are rare, with few reported cases in the literature. CASE PRESENTATION/UNASSIGNED:We present three biopsy-proven cases of subungual angiokeratomas with novel clinical features: involvement of the nail bed, clinically mimicking nodular melanoma, and involving a broad age range, with the youngest patient reported at 25 years old. Symptoms included tenderness and bleeding, while the clinical presentations ranged from evenly to irregularly pigmented nodule(s). Histopathology revealed morphologic findings; characteristics of angiokeratoma include multiple dilated vascular spaces within the superficial dermis and overlying epidermal hyperplasia. CONCLUSION/UNASSIGNED:This case series expands the known clinical presentations of nail unit angiokeratomas and emphasizes the importance of including subungual angiokeratoma in the differential diagnosis of pigmented, nodular lesions of the nail unit.

Longitudinal melanonychia (LM), a brown-black band on 1 or multiple nails, is commonly encountered in clinical practice. Benign LM may be due to exogenous (external, blood, bacterial, mycotic) or endogenous (melanin) pigment. Histopathologically, melanin-derived LM may result from overproduction of melanin by a normal number of melanocytes (melanocytic activation) due to physiologic, local, systemic, iatrogenic, syndromic, and drug-induced causes, or from benign (nail matrix nevus and lentigo) or malignant (nail unit melanoma [NUM]) melanocyte hyperplasia. A high index of suspicion is necessary to differentiate benign LM and NUM secondary to similarities in clinical presentation, especially in pediatric patients. Benign pediatric LM may exhibit clinical and onychoscopic features resembling adult NUM; thus, a conservative approach with close follow-up is recommended. Onychoscopy and histopathologic examination of nail clippings are useful initial diagnostic tools for LM, avoiding a biopsy or aiding in biopsy planning and patient triage. Nail matrix excisional biopsy is the gold standard for diagnosing/ruling out NUM. For suspicious LM, a nail matrix tangential excisional biopsy is recommended. A longitudinal excision is recommended for cases with a high-likelihood of invasive NUM, which provides information on tumor extension. Herein, we review the current literature to describe the evaluation and diagnosis of LM.

Longitudinal erythronychia (LE) is defined as a longitudinal red band of the nail(s) and is classified as localized (involvement of 1 nail) or polydactylous (involvement of more than 1 nail). The differential diagnosis is distinct for these classifications. The etiologies of localized longitudinal erythronychia are most frequently benign subungual neoplasms and less often malignancies. Polydactylous longitudinal erythronychia is typically secondary to regional or systemic diseases, including lichen planus and Darier disease. LE is a common but underrecognized clinical finding. Increased dermatologist awareness of the clinical characteristics and differential diagnosis for LE is necessary given the possibility for malignancy and associated systemic disease. In this clinical review, the clinical features, differential diagnosis, evaluation, and management of LE are described.