Melanonychia striata: clarifying behind the Black Curtain. A review on clinical evaluation and management of the 21st century

Abstract

Melanonychia striata is characterized by a tan, brown, or black longitudinal streak within the nail plate that runs from the proximal nail fold to the distal part of the nail plate.Melanonychia striata is due to increased activity of melanocytes or melanocytic hyperplasia in the nail matrix with subsequently increased melanin deposition in the nail plate. The most common cause of melanonychia striata associated with melanocytic activation is ethnic melanonychia which occurs in dark-skinned individuals. Other causes of melanonychia striata related to melanocytic activation include pregnancy, chronic local trauma, infections, medications, dermatological disorders, endocrine disorders, alkaptonuria, hemochromatosis, porphyria, graft-vs-host disease, Peutz-Jeghers syndrome, and Laugier-Hunziker syndrome. Causes of melanonychia striata associated with melanocytic hyperplasia include nail matrix melanocytic nevus, nail lentigo, and nail apparatus/subungual in situ and invasive melanoma. In most cases, melanonychia striata is a benign condition, especially in children. Consequently, most investigators advocate a wait-and-see approach. Nail apparatus/subungual melanoma should be suspected if there is an abrupt onset after middle age, personal or family history of melanoma, rapid growth, darkening of a melanonychia band, pigment variegation, blurry lateral borders, irregular elevation of the surface, a bandwidth >3 mm, proximal widening, associated nail plate dystrophy, single rather than multiple digit involvement, and periungual spread of pigmentation onto the adjacent cuticle and/or proximal and/or lateral nail folds (Hutchinson sign). Prolonged follow-up is mandatory for early detection of possible malignant changes.

Laugier–Hunziker Syndrome in an 8-Year-Old Boy with Scleral Melanocytosis, Lingual Pigmentation, Labial Pigmentation, and Melanonychia Striata

“…Melanonychia striata is more common in the thumb. Involvement of multiple digits is less common and is most commonly seen in dark-skinned individuals and individuals with connective tissue disorders [5,18,19]. Our case is unique that all the fingernails and toenails were affected.…”

“…In the mean time, we suggest ocular pigmentation be grouped under the umbrella "essential melanotic pigmentation of mucosa." Melanonychia striata is present in approximately 50 to 60% of patients with Laugier-Hunziker syndrome and may present as single, double, or multiple longitudinal stripes that runs along the longitudinal axis of the nail from the proximal nail fold to the distal nail plate or, less commonly, as homogeneous pigmentation involving one half of the nail or complete nail [3,6,9,18]. e coloration can be tan, brown, gray, or black [18].…”

Laugier‐Hunziker syndrome: a case report of the pediatric patient and review of the literature

“…The fingernails are more often affected by pigmentation than the toenails 6 . Thus, longitudinal melanonychia, also known as melanonychia striata, always requires differential diagnosis, in which LHS is included 14 …”

Subungual melanoma in situ in a 21‐year‐old man: How to manage a patient with longitudinal melanonychia from infant?

“…It is caused by melanocytic activation and/or hyperplasia including melanocytic nevus, nail lentigo, and in situ and invasive nail apparatus/subungual melanoma 1 . In children, a wait‐and‐see approach is advocated because of the much lower incidence of melanoma 1,2 …”