Longitudinal subungual acanthoma: one denomination for various clinical presentations.

BACKGROUND: Benign subungual proliferation of the distal nail matrix and bed such as longitudinal keratosis, seborrhoeic keratosis or onychocytic matricoma should belong to a single spectrum of diseases. OBJECTIVE: This article intends to demonstrate clinically and histologically the different facets of Nail unit longitudinal acanthoma. METHODS: We report three new cases that present as a longitudinal melanonychia with thickening of the nail plate in two of them and as leukoxanthonychia in the third one. We compared them with the two original cases we described in 1999, reminiscent of seborrhoeic keratosis and all the new cases published since then. RESULTS: We therefore consider that all these tumours belong to a single spectrum of diseases, we have called 'nail unit longitudinal acanthoma' which describes a histopathological process. The distinct clinical features of these tumours, melanonychia or leukoxanthonychia may be linked to their variable anatomic locations in different zones of the nail unit.

[Clinical types of onychomycosis]. / Variétés cliniques des onychomycoses.

Clinical classification of onychomycosis is based on how the pathogenic agent penetrates the unguis. The disto-lateral sub-ungual variety is the most common. Dermatophytes (especially Trichophyton rubrum) and Scytalidium in tropical regions (Sc hyalium, Sc dimidiatum) are the most frequent toenail pathogens. Progression of a yellow friable sub-ungual hyperkeratosis associated with longitudinal striations and/or xanthonychial or leuconychial zones (sometimes pigmented with Trichophyton rubrum nigricans or Scopulariopsis brevicaulis) lead rapidly to onycholysis and later to total dystrophy of the ungual plate. Associated paronychia is more common in scytalidiasis. Candida species (tropicalis, parapsilosis) and fungi (Aspergillus sp. Fusarium sp, Acremonium sp, Penicillium sp, Scopulariopsis brevicaulis) generally colonize pre-existing onycholysis. For the fingernails, candidal colonizations secondary to pre-existing onycholysis is much more frequent than primary dermatophyte or scytalidium onychomycoses which are much less hyperkeratotic than on toenails. The one hand two feet tinea syndrome caused by Trichophyton rubrum is a particular entity. Proximal sub-ungual onychomycoses without fingernail or toenail paronychia is generally caused by Trichophyton rubrum in immunodepressed subjects (AIDS). Initial proximal leuconychia progresses to the distal part of the nail. Proximal lesions associating proximal leuconychia and paronychia result from fungi, Fusarium being the most commonly identified agent. Onyxis complicating chronic paronychia, generally related to Candida colonization, occurs in subjects with particular conditions (immunodepression, distal vascular disorders). Superficial onychomycosis, e.g. superficial toenail leuconychia, is mainly due to Trichophyton interdigitale, more exceptionally to Trichophyton rubrum (children, immunodepressed), and rarely Candida (children). Endonyx onychomycosis occurs when the pathogen invades the entire thickness of the nail (milky leuconychia without sub-ungual hyperkeratosis). Trichopnyton violaceum or soudanense is the most common pathogen. Even though the clinical presentation of onychomycosis is highly suggestive of the pathogenic agent, the lack of specific criteria implies a mycological sample to confirm the diagnosis and identify the causal agent before initiating treatment.

Distal digital keratoacanthoma: two cases with a review of the literature.

BACKGROUND: Distal digital keratoacanthoma (DKA) is an uncommon tumor difficult to diagnose clinically, and even histologically, with certainty. OBJECTIVE: Our purpose is to report on two new cases and to discuss the clinical, histologic, and differential diagnosis. METHODS: We have reviewed all well documented cases published in the literature. RESULTS: No single diagnostic criterion is sufficiently sensitive and specific to be pathognomonic. CONCLUSION: The diagnosis of DKA should be based on the correlation of clinical, radiological and pathologic findings, but the tumor is frequently diagnosed histologically as "squamous cell carcinoma, keratoacanthoma type" or as keratocarcinoma.

Longitudinal melanonychia in children: a clinical and histopathologic study of 40 cases.

OBJECTIVE: Very little has been published on longitudinal melanonychia in children. Our objective was to determine the nature of melanocytic lesions in pediatric patients with longitudinal or total melanonychia and to look for correlations between clinical and histologic features. METHODS: All patients younger than 16 years of age with longitudinal or total melanonychia who were evaluated at our nail disorder outpatient clinic between September 1993 and September 1996 were included. The clinical and histologic features of the nail condition were determined in each case. RESULTS: Forty patients were included. The final diagnosis was nevus in 19 cases (junctional in 17 cases and compound in 2), lentigo in 12 cases, and functional longitudinal melanonychia in 9. The latter corresponded to a hyperpigmentation caused by melanocytic activation with no increase in the number of melanocytes. None of the patients had melanoma. Appearance within the first year of life, periungual pigmentation, and total melanonychia were consistent features in patients with melanocytic hyperplasia (lentigo or nevus). Early onset of a dark broad lesion in a white patient was typical of melanocytic hyperplasia, although none of these features were pathognomonic. CONCLUSION: Benign melanocytic hyperplasia (lentigo or nevus) was the cause of 77.5% of cases of longitudinal melanonychia in our overall pediatric population and of 85% of cases in the subset of white patients. All the remaining cases of longitudinal melanonychia were the result of melanocytic activation.