Histopathologic features of melanoma in difficult-to-diagnose lesions: A case-control study.

BACKGROUND: Dermatopathology is considered the gold standard for melanoma diagnosis, but a subset of cases is difficult to diagnose by histopathology. OBJECTIVE: The goals of this study were to measure the accuracy of histopathologic features in difficult-to-diagnose melanocytic tumors and the interobserver agreement of those features. METHODS: This is a case-control study of histopathologic features of melanoma in 100 difficult-to-diagnose melanocytic neoplasms (40 melanomas and 60 nevi). Slides were blindly evaluated by 5 dermatopathologists. Frequencies, predictive values, and interobserver agreement were calculated. Univariate and multivariate logistic regression analyses were performed to identify the most influential features in arriving at a diagnosis of melanoma. RESULTS: Asymmetry, single-cell melanocytosis, solar elastosis, pagetoid melanocytosis, and broad surface diameter were most influential in arriving at a diagnosis of melanoma. Asymmetry and single-cell melanocytosis were most predictive of melanoma. Fleiss kappa was <0.6 for interobserver agreement in 9/10 histopathologic features of melanoma. LIMITATIONS: This study is limited by the small sample size, selection bias, and binary classification of melanocytic lesions. CONCLUSION: Our results indicate histopathologic features of melanoma in difficult-to-diagnose lesions vary in accuracy and reproducibility.

Diagnostic concordance rates in the subtyping of basal cell carcinoma by different dermatopathologists.

BACKGROUND: There are numerous subtypes of basal cell carcinoma (BCC). Defining the histopathologic subtype is an essential element in patient management, but there is little known data regarding interobserver precision in subtyping BCC. METHODS: We studied interobserver variance between six board-certified dermatopathologists who subtyped 100 BCCs in a blinded fashion. We used kappa statistic to calculate the concordance in suggested subtype by different dermatopathologists. Provided diagnoses were then re-categorized into low-risk and high-risk phenotypes, and kappa statistic for concordance on high-risk BCC was determined. RESULTS: The overall κ statistic was 0.301, indicating fair agreement among the six observers. Superficial and fibroepithelial BCC had the highest individual kappa statistics. When subtypes were re-classified into a two-tier system of high-risk and low-risk phenotypes, there was substantial interobserver agreement on high-risk BCC with a κ statistic of 0.699. CONCLUSION: These results suggest only fair agreement among dermatopathologists on specific BCC subtypes, but substantial agreement on superficial, fibroepithelial and high-risk BCC growth patterns. A simplified classification system comprised of superficial, fibroepithelial, nodular and infiltrative subtypes would increase interobserver precision and facilitate clinical decision-making.

Lymphocutaneous nocardiosis: a case report and review of the literature.

Nocardiosis remains a fairly uncommon disease in the United States. Cutaneous nocardiosis is one of many infections that can spread in a sporotrichoid pattern and therefore can be difficult to diagnose without a high index of suspicion. It is mainly caused by Nocardia asteroides and Nocardia brasiliensis, with N brasiliensis isolated in most cases of lymphocutaneous nocardiosis. We present a case of lymphocutaneous nocardiosis in a 65-year-old immunosuppressed man and review the literature.

Ultraviolet exposure is a reinforcing stimulus in frequent indoor tanners.

BACKGROUND: Investigations into tanners' reasons for tanning have focused primarily on the perception of improved appearance. Reported relaxing effects of tanning suggest the possibility of a physiologic effect of UV that drives tanning behavior. OBJECTIVE: We sought to determine if there is a physiologic reinforcing effect of UV exposure, separate from appearance motivation, that may contribute to tanning behavior. METHODS: We determined the reinforcing effect of UV light in a series of controlled, blinded, repeated-choice trials of UV carefully designed to separate as cleanly as possible reinforcing effects of UV exposure from other factors including perceived benefits of having a tan. A total of 14 young adults who used tanning beds regularly were exposed to otherwise identical UV and non-UV tanning bed stimuli on Mondays and Wednesdays for 6 weeks. On Fridays, participants had concurrent access to the two beds. The primary dependent variable was the percentage of choice sessions during which more UV than non-UV tanning was chosen. RESULTS: In all, 12 participants chose additional tanning exposure on Fridays and, of these, 11 consistently used the UV bed for that exposure. Of the total 41 occasions when participants chose to tan on Friday, 39 sessions (95%) were for the UV bed and only two for the non-UV bed. A more relaxed and less tense mood was reported after UV exposure compared with after non-UV exposure (P=.008 and P=.002, respectively). DISCUSSION: When exposed to UV and non-UV under blinded conditions, frequent tanners can distinguish the two conditions and undertake further UV exposure, indicating that UV is a reinforcing stimulus. The relaxing and reinforcing effects of UV exposure contribute to tanning behavior in frequent tanners and should be explored in greater detail.

Pruritus: a review.

The history, neurophysiology, clinical aspects and treatment of pruritus are reviewed in this article. The different forms of pruritus in dermatological and systemic diseases are described, and the various aetiologies and pathophysiology of pruritus in systemic diseases are discussed. Lack of understanding of the neurophysiology and pathophysiology of pruritus has hampered the development of adequate therapies. Nevertheless, the discovery of primary afferent neurons and, presumably, second-order neurons with typical histamine responses mediating pruritic sensations can be regarded as a breakthrough in our understanding of the mechanisms behind pruritus. The number of experimental and therapeutic studies has greatly increased during the past few years, reflecting an increased interest in this topic. However, further effort is needed to develop new therapeutic concepts and clarify some confusion arising from promising case reports and uncontrolled clinical studies. A precise work-up for evaluating patients with pruritus is proposed, which may help the physician to identify the underlying causes and thus to treat the patient appropriately.

Visual discrimination testing of ultraviolet transmitting and ultraviolet blocking acrylic thermoplastics.

BACKGROUND: Visual perception has hindered the development of blinded, placebo-controlled ultraviolet light exposure conditions in humans. New acrylic thermoplastics that block or transmit ultraviolet light have visual properties that may provide a solution. METHODS: In a series of triangle taste tests, 60 subjects were tested for the ability to visually perceive ultraviolet light transmission by two of four types of acrylic thermoplastics. RESULTS: Forty-six of sixty (67%) subjects were unable to visually detect ultraviolet light transmitting acrylics among ultraviolet blocking acrylics in both an ambient light background condition and an ambient light background condition with ultraviolet A light supplementation. CONCLUSION: Acrylic thermoplastics allow for the production of blinded, placebo-controlled ultraviolet light exposure conditions by eliminating visual discrimination differences between active and control groups.

Occupational allergic contact dermatitis is more prevalent than irritant contact dermatitis: a 5-year study.

BACKGROUND: Irritant contact dermatitis is thought to be the leading cause of occupational skin disease in the United States. Recent reports suggest otherwise. OBJECTIVES: The purposes of this study were to determine the prevalence of allergic and irritant forms of occupational contact dermatitis in the population seen at a Midwestern dermatologic referral clinic, report professions commonly affected by occupational skin disease, and indicate which substances are frequent allergens. METHODS: A retrospective analysis of patch test data collected at the University of Kansas between 1994 and 1999 was performed. RESULTS: Of 537 patients who underwent patch testing, 135 (25%) had occupational skin disease. Allergic contact dermatitis affected 81 (60%) patients, and irritant contact dermatitis was found in 46 (34%). Health care professionals, machinists, and construction workers accounted for nearly half of all patients with occupational skin disease. Nickel sulfate, glutaraldehyde, and thiuram mix were the most common allergens. CONCLUSION: Patch tests with a wider array of allergens than those currently available in the United States are needed to prevent misdiagnosis of occupational contact dermatitis.