Classification of non-tumorous skin pigmentation disorders using voting based probabilistic linear discriminant analysis.

Non-tumorous skin pigmentation disorders can have a huge negative emotional impact on patients. The correct diagnosis of these disorders is essential for proper treatments to be instituted. In this paper, we present a computerized method for classifying five non-tumorous skin pigmentation disorders (i.e., freckles, lentigines, Hori's nevus, melasma and nevus of Ota) based on probabilistic linear discriminant analysis (PLDA). To address the large within-class variance problem with pigmentation images, a voting based PLDA (V-PLDA) approach is proposed. The proposed V-PLDA method is tested on a dataset that contains 150 real-world images taken from patients. It is shown that the proposed V-PLDA method obtains significantly higher classification accuracy (4% or more with p< 0.001 in the analysis of variance (ANOVA) test) than the original PLDA method, as well as several state-of-the-art image classification methods. To the authors' best knowledge, this is the first study that focuses on the non-tumorous skin pigmentation image classification problem. Therefore, this paper could provide a benchmark for subsequent research on this topic. Additionally, the proposed V-PLDA method demonstrates promising performance in clinical applications related to skin pigmentation disorders.

A retrospective clinico-pathological study comparing lichen planus pigmentosus with ashy dermatosis.

BACKGROUND/OBJECTIVES: Controversy persists as to whether lichen planus pigmentosus and ashy dermatosis are separate clinical entities. This study was conducted to examine the clinicopathological features and treatment outcome of the two conditions. METHODS: A retrospective medical chart review of all patients who were diagnosed with lichen planus pigmentosus or ashy dermatosis was conducted. The information collected included the participants' age at onset, site of onset, duration of disease, presence of precipitating factors, distribution of disease, pigmentation and presence of symptoms. In patients from whom a biopsy was taken the histopathological reports were included. RESULTS: Altogether 26 patients with ashy dermatosis and 29 with lichen planus pigmentosus were included in the study. Compared with ashy dermatosis, lichen planus pigmentosus had a more localised distribution with a preponderance for facial involvement, compared with the truncal preponderance in ashy dermatosis. Ashy dermatosis tended to have a more stable clinical course than lichen planus pigmentosus, which was more likely to wax and wane. The utility of histopathology in differentiating between the two conditions is low. CONCLUSION: Ashy dermatosis and lichen planus pigmentosus, as defined in this study, appear to be two separate clinical entities with distinguishable clinical features and natural histories.

Noninvasive real-time characterization of non-melanoma skin cancers with handheld optoacoustic probes.

Currently, imaging technologies that enable dermsurgeons to visualize non-melanoma skin cancers (NMSC) in vivo preoperatively are lacking, resulting in excessive or incomplete removal. Multispectral optoacoustic tomography (MSOT) is a volumetric imaging tool to differentiate tissue chromophores and exogenous contrast agents, based on differences in their spectral signatures and used for high-resolution imaging of functional and molecular contrast at centimeter scale depth. We performed MSOT imaging with two- and three-dimensional handheld scanners on 21 Asian patients with NMSC. The tumors and their oxygenation parameters could be distinguished from normal skin endogenously. The lesion dimensions and depths were extracted from the spectral melanin component with three-dimensional spatial resolution up to 80 µm. The intraclass correlation coefficient correlating tumor dimension measurements between MSOT and ex vivo histology of excised tumors, showed good correlation. Real-time 3D imaging was found to provide information on lesion morphology and its underlying neovasculature, indicators of the tumor's aggressiveness.

Three cases of transition from pemphigus vulgaris to pemphigus foliaceus confirmed by desmoglein ELISA.

We report 3 cases of pemphigus vulgaris (PV) confirmed by histology and direct and indirect immunofluorescence that showed transition to pemphigus foliaceus (PF) 2-4 years from the time of disease onset. Desmoglein (Dsg) ELISA testing of the sera from these 3 patients in the later stages of their disease showed the presence of anti-Dsg1 antibodies and the absence of anti-Dsg3 antibodies. These patients were on prednisolone and immunosuppressives at the time the sera were tested, and it is unclear if the transition from PV to PF is a permanent one or whether it is due to preferential suppression of Dsg3 antibodies below a certain threshold. Previously reported cases of transition from PV to PF and PF to PV are summarized.