A Clinicoepidemiological Study of Melanoma in Young Patients (20 Years of Age or Less) in Alberta, Canada, From 1992 to 2011

The epidemiological trends of malignant melanoma have been well described in the literature. However, there remains a paucity of population-based studies assessing melanoma epidemiology in our younger patients (20 years of age or less). Other studies indicate that melanoma incidence has risen in pediatric populations over the last several decades and that these tumors may display different clinical characteristics from those arising in adult populations. We conducted a retrospective, population-based analysis of all incident cases of melanoma occurring in young patients aged ≤20 years in Alberta from 1992 to 2011. Information, including patient age, sex, anatomical location, date of diagnosis, histological subtype (if available), level of invasion, and date of death (if applicable), was obtained from the Alberta Cancer Registry. All cases occurring during a 10-year period from 1993 to 2011 have been reviewed. A total of 71 cases were diagnosed during this time (63% female and 37% male). Age range was 0-20 years (mean of 17.5 years). Truncal melanomas made up 36% of cases, while 28% occurred on the lower limbs, 17% on the upper limbs, and 18% in the head and neck region. Average Breslow thickness was 1.97 mm; 67% of tumors were less than 1 mm thick. Unfortunately, 8 of 71 patients died from their disease. Overall, the incidence of melanoma in patients aged ≤20 years appeared to decrease in Alberta in the past 20 years; however, there has been an increase in the thickness of melanoma at diagnosis, which needs to be addressed.

Crisaborole 2% Ointment (Eucrisa) for Atopic Dermatitis

Atopic dermatitis is a common cutaneous disease with significant morbidity affecting children and adults. The mainstay of atopic dermatitis therapy has typically included emollients, topical corticosteroids, and topical calcineurin inhibitors. Among the newer advances recently introduced is crisaborole (Eucrisa™), a phosphodiesterase type-4 inhibitor (PDE-4) for the treatment of mild moderate atopic dermatitis. Evidence from phase 3 trials demonstrates crisaborole as an efficacious topical agent with a favorable safety profile and limited systemic exposure. While the efficacy of crisaborole compared to existing therapies remains unknown, crisaborole is a promising candidate in the treatment of atopic dermatitis.

Disfiguring ulcerative neutrophilic dermatosis secondary to doxycycline and isotretinoin in an adolescent boy with acne conglobata

Acne fulminans is an uncommon and debilitating disease that presents as an acute eruption of nodular and ulcerative acne lesions in association with systemic symptoms. It occurs commonly during treatment of severe acne (eg, acne conglobata) with isotretinoin in young adolescent male patients. Isotretinoin and doxycycline also can potentially induce development of neutrophilic dermatoses in patients with severe acne lesions, which are characterized by the acute appearance of painful ulcerative papulonodules accompanied by systemic symptoms including fever and leukocytosis. We report a challenging case of a 13-year-old adolescent boy who acutely developed hundreds of ulcerative plaques as well as systemic symptoms after being treated with doxycycline and isotretinoin for acne conglobata. He was treated with prednisone, dapsone, and colchicine and had to switch to cyclosporine to achieve relief from his condition.

Vitamin B Derivative (Nicotinamide)Appears to Reduce Skin Cancer Risk

Nicotinamide, an amide form of vitamin B3, has shown the potential to treat a variety of dermatological conditions, including acne, rosacea, and atopic dermatitis. Recent studies have demonstrated the role of nicotinamide, in both topical and oral forms, as a chemopreventive agent against skin cancer. Its anti-carcinogenic role may be due to its ability to enhance DNA repair and prevent ultraviolet (UV)-induced immunosuppression, which is known to contribute to the progression of pre-malignant lesions. Furthermore, nicotinamide is a precursor of essential coenzymes for many important reactions in the body, including the production of nicotinamide adenine dinucleotide (NAD). NAD is a key coenzyme in the synthesis of adenosine triphosphate (ATP), which transports chemical energy within cells. Therefore, nicotinamide plays a significant role in supporting energy-dependent cellular processes, including DNA repair.

A Clinicopathologic Review of a Case Series of Dermatofibrosarcoma Protuberans with Fibrosarcomatous Differentiation

Background:

Dermatofibrosarcoma protuberans with fibrosarcomatous differentiation (DFSP-FS) is a rare variant of DFSP with a more aggressive clinical course, characterized by higher rates of local recurrence, metastasis, and death.

Methods:

We conducted a clinicopathologic review of all DFSP-FS cases that occurred in Alberta, Canada, from 1997 to 2007.

Results:

Of the 75 DFSP cases reviewed, 4 demonstrated fibrosarcomatous differentiation. Three patients were female and one was male, and the age range was 25 to 76 years. Three tumors invaded to skeletal muscle, whereas one invaded to subcutaneous tissue only. Although perineural invasion was noted in all four cases, none exhibited lymphovascular space invasion. One local recurrence developed, and two of four tumors metastasized. Metastasis was associated with tumor size, tumor necrosis, grenz zone involvement, ulceration, thickness, and tumor grade. One patient died within 5 years of diagnosis.

Conclusion:

DFSP-FS represents a more aggressive subtype of DFSP. Several features of DFSP-FS may impart a higher risk of metastasis.

Fatal Case of Vulvar Pyoderma Gangrenosum with Pulmonary Involvement: Case Presentation and Literature Review

Introduction:

We report a case of a 61-year-old woman with locally destructive vulvar pyoderma gangrenosum (PG) with pulmonary involvement who was refractory to numerous systemic therapies and developed complications resulting in her demise.

Objective:

To report a rare case of treatment-resistant vulvar PG with pulmonary involvement that proved to be fatal.

Methods:

PubMed was used to search for other reports that discuss PG, or more specifically perigenital PG, with pulmonary involvement.

Results and Conclusion:

A thorough review of the literature revealed 33 cases of PG with pulmonary involvement, with only 4 involving the perigenital region. We report the second case of a female with vulvar PG and pulmonary involvement. In contrast to the first case described, our patient did not respond to systemic therapy, and, ultimately, her disease was fatal. It is hoped that with continued documentation of this rare and potentially lethal presentation of PG, physicians will determine more effective treatments.

Cutaneous squamous cell carcinoma in two pediatric lung transplant patients on prolonged voriconazole treatment

Oral voriconazole is commonly used for treatment and prophylaxis of invasive fungal disease post-LTx. Development of cutaneous SCC has been described in adult LTx recipients, although it is extremely rare in children. We describe two Caucasian children who developed cutaneous SCC beyond three yr post-LTx. Both developed severe photosensitivity, actinic keratosis and required curative surgical excision of the cutaneous SCC lesions. Neither patient developed metastatic lesions nor had allograft dysfunction as a result of the SCC or the change in medical treatments. The effect of voriconazole on the development of malignant skin lesions is discussed and a recommendation on dermatologic surveillance, preventive measures against phototoxicity and early treatment of SCC are provided.

Multiple soft-mode vibrations of lead zirconate

Polarized Raman, IR, and time-domain THz spectroscopy of orthorhombic lead zirconate single crystals have yielded a comprehensive picture of temperature-dependent quasiharmonic frequencies of its low-frequency phonon modes. It is argued that these modes primarily involve vibrations of Pb ions and librations of oxygen octahedra. Their relation to phonon modes of the parent cubic phase is proposed. Counts of the observed IR and Raman active modes belonging to distinct irreducible representations agree quite well with group-theory predictions. Analysis of the results yields insight into the phase transition mechanism, involving a soft ferroelectric branch coupled by a trilinear term to another two oxygen octahedra tilt modes.

Epidemiology of Sebaceous Carcinoma in Alberta, Canada, from 1988 to 2007

Background:

The epidemiology of sebaceous carcinoma (SC) has not previously been examined in a Canadian population.

Objective:

To determine the epidemiologic trends of SC in Alberta, Canada, from 1988 to 2007.

Methods:

This study was a population-based, retrospective, epidemiologic analysis of SC in Alberta over a 20-year span.

Results:

Over the study period, the age-standardized SC incidence increased from 0.22 per 100,000 to 0.65 per 100,000. Sebaceous carcinoma is a cancer that predominantly affects the elderly (over 85% of cases were in persons 60 years or older). Interestingly, the face (37.7% of cases), not the eyelids (26.2% of cases), was the most frequently affected site overall. Gender-specific trends reflected a slight male predominance (1.4:1) and significant differences in anatomic distribution between the sexes.

Conclusion:

For unexplained reasons, there has been a threefold increase in SC incidence in Alberta over the last two decades. In addition, there are significant gender-specific differences in the anatomic distribution of SC.

Contexte:

L'épidémiologie du carcinome sébacé (CS) n'a jamais fait l'objet d'étude au Canada.

Objectif:

L'étude visait à déterminer les tendances épidémiologiques du CS en Alberta, au Canada, de 1988 à 2007.

Méthodes:

Il s'agit d'une analyse épidémiologique, rétrospective, fondée sur la population, du CS, en Alberta, sur une période de 20 ans.

Résultats:

Au cours de la période à l'étude, l'incidence du CS normalisée selon l'âge est passée de 0.22 pour 100,000 à 0.65 pour 100,000. Le carcinome sébacé est un cancer qui touche surtout les personnes âgées (plus de 85% des cas se comptaient parmi les personnes de 60 ans et plus). Point intéressant, la région le plus souvent touchée, dans l'ensemble, était la face (37.7% des cas), et non les paupières (26.2% des cas). Les tendances propres à chaque sexe ont révélé une fréquence légèrement plus élevée chez les hommes que chez les femmes (1.4/1) et des différences importantes entre les sexes quant à la répartition anatomique du siège des lésions.

Conclusion:

Pour des raisons inconnues, l'incidence du CS a triplé en Alberta au cours des deux dernières décennies. De plus, il existe des différences importantes entre les sexes quant à la répartition anatomique du CS.

Epidemiology of dermatofibrosarcoma protuberans in Alberta, Canada, from 1988 to 2007

BACKGROUND

There have only been a few population-based, epidemiologic studies assessing dermatofibrosarcoma protuberans (DFSP).

OBJECTIVE

To assess the epidemiology of DFSP in Alberta, Canada, over a 20-year period.

METHODS

A population-based, retrospective analysis of all cases of DFSP in Alberta was conducted using data from the Alberta Cancer Registry. Sex-, age-, and anatomical location-specific incidence rates and trends were determined.

RESULTS

The overall age-standardized incidence rate of DFSP remained stable at 0.93 per 100,000. DFSP prevalence was highest in individuals aged 20 to 39 (46.8%), followed by those aged 40 to 59 (34.0%), 60 and older (14.7%), and lastly younger than 20 (4.5%). The mean age at diagnosis was 41.1 (women) and 43.1 (men). The incidence of DFSP in men and women has shown a dramatic shift such that incidence in women has increased 3.2% per year, whereas in men it has decreased 2.7% per year. In women, DFSP incidence increased on the trunk and decreased on the upper extremities.

CONCLUSION

The age-standardized incidence of DFSP observed is nearly twice as high as previously reported and has remained stable. The incidence is increasing in women and decreasing in men. DFSP primarily affects young to middle-aged adults and most commonly presents on the trunk.

Cadherin switch from E- to N-cadherin in melanoma progression is regulated by the PI3K/PTEN pathway through Twist and Snail

BACKGROUND

Transition of normal melanocytic cells to malignant melanoma has characteristic features of epithelial to mesenchymal transition. This includes the disruption of the adherens junctions caused by the downregulation of E-cadherin and the upregulation of N-cadherin. The cadherins have functional importance in normal skin homeostasis and melanoma development; however, the exact mechanism(s) that regulate the 'cadherin switch' are unclear.

OBJECTIVES

To determine the mechanistic role of the PI3K/PTEN pathway in regulating the change in cadherin phenotype during melanoma progression.

METHODS

Using a panel of cell lines representative of the phases of melanoma progression, we determined cellular expressions of the components of the PI3K/PTEN pathway, E- and N-cadherin, and the transcriptional regulators Twist, Snail and Slug with Western blot and immunofluorescence analysis. Transcriptional regulation of E-cadherin, N-cadherin, Twist and Snail by the PI3K/PTEN pathway was confirmed using quantitative reverse transcription-polymerase chain reaction.

RESULTS

Loss or inactivity of PTEN correlated with the switch in cadherin phenotype during melanoma progression. PTEN-null or inactive cells exhibited high levels of phosphorylated protein kinase B (PKB)/AKT (Serine 473) (PKB-Ser473-P), undetectable levels of E-cadherin and high levels of N-cadherin. Re-introduction of PTEN or treatment with the PI3K inhibitor Wortmannin resulted in the re-expression of E-cadherin and downregulation of N-cadherin. This cadherin switch was regulated at the transcriptional level by Twist and Snail which were, in turn, transcriptionally regulated by the PI3K pathway. Although E-cadherin was re-expressed, it failed to localize to the plasma membrane.

CONCLUSIONS

The PI3K/PTEN pathway transcriptionally regulates the 'cadherin switch' via transcriptional regulation of Twist and Snail but does not regulate the localization of E-cadherin to the plasma membrane.

Gouy shift correction for highly accurate refractive index retrieval in time-domain terahertz spectroscopy

Terahertz spectroscopic measurements are usually performed in focused beam geometry while the standard routine for the retrieval of the sample refractive index assumes plane-wave approximation. In this paper we propose a model for the transmission function which accounts for spatially limited Gaussian terahertz beams. We demonstrate experimentally its validity and applicability for an accurate extraction of the refractive index from experimental data.

Influence of the electron-cation interaction on electron mobility in dye-sensitized ZnO and TiO2 nanocrystals: a study using ultrafast terahertz spectroscopy

Charge transport and recombination in nanostructured semiconductors are poorly understood key processes in dye-sensitized solar cells. We have employed time-resolved spectroscopies in the terahertz and visible spectral regions supplemented with Monte Carlo simulations to obtain unique information on these processes. Our results show that charge transport in the active solar cell material can be very different from that in nonsensitized semiconductors, due to strong electrostatic interaction between injected electrons and dye cations at the surface of the semiconductor nanoparticle. For ZnO, this leads to formation of an electron-cation complex which causes fast charge recombination and dramatically decreases the electron mobility even after the dissociation of the complex. Sensitized TiO2 does not suffer from this problem due to its high permittivity efficiently screening the charges.

Broadband dielectric terahertz metamaterials with negative permeability

We present a design of dielectric metamaterials exhibiting a broad range of negative effective permeability in the terahertz spectral region. The investigated structures consist of an array of high-permittivity rods that exhibit a series of Mie resonances giving rise to the effective magnetic response. The spectral positions of resonances depend on the geometrical parameters of the rods and on their permittivity, which define the resonant confinement of the electromagnetic field within the rods. The electromagnetic coupling between the adjacent rods is negligible. With a suitable aspect ratio of the rods, a broadband magnetic response can be obtained.

Coexistence of the phonon and relaxation soft modes in the terahertz dielectric response of tetragonal BaTiO3

The dielectric response to infrared waves polarized along the tetragonal axis of a ferroelectric single-domain crystal of BaTiO3 was determined by time-domain THz spectroscopy and Fourier-transform infrared reflectivity techniques. In addition to the three well-known polar lattice modes, the experiment shows an additional mode of the relaxation type in the THz spectral region, which accounts for the Curie-Weiss behavior of the c-axis dielectric constant. A comparison of experimental results with ab initio based effective-Hamiltonian simulations allows us to elucidate its relation to the order-disorder model of Comes, Lambert, and Guinier [Solid State Commun. 6, 715 (1968)10.1016/0038-1098(68)90571-1].

Propagation of terahertz pulses in photoexcited media: Analytical theory for layered systems

Optical pump-terahertz probe spectroscopy has become a widely used experimental tool for the investigation of the ultrafast far-infrared response of polar systems. In this paper the authors present an analytical method of calculating the propagation of ultrashort terahertz pulses in photoexcited media. The transient terahertz wave form transmitted through the sample is equal to a product of the incident terahertz field (at a mixed frequency), transient susceptibility, and a so called transfer function which depends on the properties of the sample in equilibrium. The form of the transfer function is derived for general layered systems and for specific cases including one-dimensional photonic crystals, thin films, and bulk samples. Simplified expressions directly applicable to the analysis of the experimental results related to the most common sample geometries are shown and discussed.

Fast one-dimensional photonic crystal modulators for the terahertz range

Optically controlled one-dimensional photonic crystal structures for the THz range are studied both theoretically and experimentally. A GaAs:Cr layer constitutes a defect in the photonic crystals studied; its photoexcitation by 800 nm optical femtosecond pulses leads to the modulation of the THz beam. Since the THz field can be localized in the photoexcited layer of the photonic crystal, the interaction between photocarriers and THz light is strengthened and yields an appreciable modulation of the THz output beam even for low optical pump fluences. Optimum resonant structures are found, constructed and experimentally studied. The dynamical response of these elements is shown to be controlled by the lifetime of THz photons in the resonator and by the free carrier lifetime. The time response of the structures studied is shorter than 330 ps.

Ultrafast opto-terahertz photonic crystal modulator

We present an agile optically controlled switch or modulator of terahertz (THz) radiation. The element is based on a one-dimensional photonic crystal with a GaAs wafer inserted in the middle as a defect layer. The THz electric field is enhanced in the photonic structure at the surfaces of the GaAs wafer. Excitation of the front GaAs surface by ultrashort 810 nm laser pulses then leads to an efficient modulation of the THz beam even at low photocarrier concentrations (approximately 10(16) cm(-3)). The response time of the element to pulsed photoexcitation is about 130 ps.

Active optical control of the terahertz reflectivity of high-resistivity semiconductors

We study theoretically and demonstrate experimentally light-controllable terahertz reflectivity of high-resistivity semiconductor wafers. Photocarriers created by interband light absorption form a thin conducting layer at the semiconductor surface, which allows the terahertz reflectivity of the element to be tuned between antireflective (R <3%) and highly reflective (R >85%) limits by means of the intensity and wavelength of the optical illumination.

Ultrafast far-infrared dynamics probed by terahertz pulses: A frequency-domain approach. II. Applications

We present data obtained by time-resolved terahertz spectroscopy in selected semiconducting and molecular systems exhibiting subpicosecond far-infrared dynamics. We use a frequency-domain method which eliminates the influence of instrumental functions and artifacts due to frequency mixing and yields a two-dimensional transient conductivity of the photoexcited sample. This technique enables improving the attainable experimental time resolution and allows a simple qualitative interpretation of the results without a priori modeling. The quantitative interpretation is based on the time-dependent Drude and damped harmonic oscillator models.

Ultrafast far-infrared dynamics probed by terahertz pulses: A frequency domain approach. I. Model systems

Time-resolved terahertz spectroscopy has become a widely used experimental tool for the investigation of ultrafast dynamics of polar systems in the far infrared. We have recently proposed an analytical method for the extraction of a transient two-dimensional susceptibility from the experimental data [Nĕmec, Kadlec, and Kuzel, J. Chem. Phys. 117, 8454 (2002)]. In the present paper the methodology of optical pump-terahertz probe experiments is further developed for direct application in realistic experimental situations. The expected two-dimensional transient response function is calculated for a number of model cases (including Drude dynamics of free carriers, harmonic and anharmonic oscillator modes); these results serve as a basis for the interpretation of experimental results. We discuss also the cases where only partial (one-dimensional) information about the system dynamics can be experimentally obtained.

Highly tunable photonic crystal filter for the terahertz range

By use of an incipient ferroelectric, SrTiO3, as a defect material inserted into a periodic structure of alternating layers of quartz and high-permittivity ceramic, thermal tuning of a single defect mode over the entire lowest forbidden band was obtained. The tunability of this compact structure reached 60%.