Objective measurement of erythema in psoriasis using digital color photography with color calibration.

BACKGROUND: Traditional metrics for evaluating the severity of psoriasis are subjective, which complicates efforts to measure effective treatments in clinical trials. METHODS: We collected images of psoriasis plaques and calibrated the coloration of the images according to an included color card. Features were extracted from the images and used to train a linear discriminant analysis classifier with cross-validation to automatically classify the degree of erythema. The results were tested against numerical scores obtained by a panel of dermatologists using a standard rating system. RESULTS: Quantitative measures of erythema based on the digital color images showed good agreement with subjective assessment of erythema severity (κ = 0.4203). The color calibration process improved the agreement from κ = 0.2364 to κ = 0.4203. CONCLUSION: We propose a method for the objective measurement of the psoriasis severity parameter of erythema and show that the calibration process improved the results.

Laser transmission through transparent membranes used in cutaneous laser treatment.

BACKGROUND: Some clinicians perform cutaneous laser treatments through transparent membranes to protect themselves and the surroundings from contamination by ejected tissue particles. Transmissibility of these membranes influences the tissue irradiance. OBJECTIVE: We compared the optical transmissibility of 8 membranes. METHODS: In part 1, a Schwartz Electro-Optics Q-switched alexandrite laser (wavelength of 720-800 nm, beam diameter of 3 mm) was directed through 8 membranes. A Molectron JD 2000 Joulemeter Ratiometer obtained measurements of percent loss of laser energy (for calculation of percent transmission) through each. To evaluate other wavelengths used in skin treatment, an SLM Aminco UV-VIS model 2000 spectrophotometer measured variance of transmission over a spectral region from 350 to 900 nm in 4 of the membranes. RESULTS: The samples listed in order of increasing amounts of light energy lost across the membrane as compared with control (direct irradiation) were as follows: (1) Handi Wrap plastic wrap: 7% loss, 93% transmission; (2) glass slide: 8% loss; (3) Bioclusive transparent dressing: 11% loss; (4) Tegaderm transparent dressing: 26% loss; (5) Vigilon dressing without plastic backing: 34% loss; (6) Vigilon dressing with one layer of plastic backing: 37% loss; (7) Acuderm dressing: 41% loss; and (8) OpSite IV: 48% loss. CONCLUSIONS: Transmissibility of the interposed membranes must be considered when determining the dosimetry of light energy required by the target tissue.

Vohwinkel's syndrome in three generations.

Vohwinkel's syndrome or keratoderma hereditaria mutilans is a diffuse, honeycombed, palmar, and plantar keratosis usually accompanied by pseudoainhum near the distal interphalangeal creases. The mutilating keratoderma associated with sensorineural hearing loss is thought to have an etiologic basis, resting on a mutation of the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26). This specific mutation results in impaired epidermal differentiation as well as inner ear function. We describe a patient with Vohwinkel's syndrome accompanied by high-frequency sensorineural hearing loss whose mother and son were similarly affected.

An overview of poxviruses.

The poxvirus family is a diverse and interesting group of viruses that affect both humans and animals. Poxviruses are epitheliotropic and therefore are of interest to the dermatologist. The genera of poxviruses known to affect humans are Orthopoxvirus, Parapoxvirus, Molluscipoxvirus, and Yatapoxvirus. The different poxviruses are reviewed, including their history, incidence, clinical presentation, and treatment.

Bacteriology of inflamed and uninflamed epidermal inclusion cysts.

OBJECTIVE: To determine whether inflamed and uninflamed epidermoid cysts differ in the number and/or type of bacteria inhabiting them. DESIGN: A controlled study. We obtained aerobic and anaerobic bacterial culture specimens from 25 inflamed and 25 uninflamed epidermoid cysts. SETTING: A university medical center. PATIENTS: Nonimmunocompromised adults without recent systemic use of antibiotics. RESULTS: The 2 groups did not differ significantly with respect to number of bacterial isolates, "no growth" cultures, and aerobic, anaerobic, or potential pathogens cultured. CONCLUSIONS: The microbiological milieu of inflamed epidermoid cysts is similar to that of uninflamed cysts. Possible mechanisms for inflammation are discussed.

Dye-enhanced diode laser photothermal ablation of skin.

BACKGROUND: Near-infrared diode lasers are promising new light sources. However, their applications for rapid and precise removal of tissue is limited because their radiation is poorly absorbed by most tissue. OBJECTIVE: Our purpose was to determine the interaction of diode laser radiation with tissue by topically applying absorbing dye to enhance laser-tissue interaction and to examine the ability of this approach to create superficial and localized thermal effects in skin. METHODS: Immediate and long-term responses of guinea pig skin to low-power (3 to 5 W X 1 sec) diode laser (805 nm) irradiation in conjunction with indocyanine green as a dye were studied. Tissue response was characterized on the basis of gross and histopathologic analysis of biopsy specimens taken at different times. RESULTS: The observed depths of thermal damage with dye were greater than those produced by diode laser used alone at higher power settings (10 W X 1 sec). CONCLUSION: Interaction of diode laser radiation enhanced by topical application of dye causes localized superficial thermal effects in skin. This may offer a new modality in the treatment of superficial lesions.

The Q-switched Alexandrite laser's effects on tattoos in guinea pigs and harvested human skin.

BACKGROUND: Developmental work in tattoo removal is currently carried out in animal models whose skin has different optical and mechanical properties from human skin. OBJECTIVE: To observe laser effects on tattoos in a new human skin model and that of in vivo guinea pig skin. METHODS: A comparison of the efficacy of the Q-switched Alexandrite laser (750 nm, 100-120 nanoseconds) in tattooed harvested human skin and guinea pig skin was performed. Visual assessments as well as histologic and electron microscopy evaluation before and after treatment are reported. RESULTS: Mild to moderate clearing of black tattoo pigment, as judged by visual assessment, was found after one laser treatment in both the in vitro human skin model and guinea pig skin. Blue and green ink showed similar results to black ink in human skin whereas red and yellow ink did not respond in our model. CONCLUSION: Possible mechanisms of tattoo lightening and the usefulness of the in vitro human skin model are discussed.

The frequency of erythromycin-resistant Staphylococcus aureus in impetiginized dermatoses.

A trend toward increasing resistance of Staphylococcus aureus to standard antibiotic therapy has been reported. Specimens were taken from 98 patients in our outpatient staff clinic who had clinical signs of superficial skin infections. Patients with erythromycin-resistant S. aureus were contacted by telephone or seen in clinic. The organism was found in 87% of patients. Twenty-two (26%) of the 85 cultures that grew S. aureus were resistant to erythromycin. Treatment failure occurred in one of these patients. We conclude that S. aureus is the most common causative organism in secondary skin infections and impetigo in our patient population. Despite significant erythromycin resistance, there was a low frequency of treatment failure in this group. Erythromycin may still be a reasonable agent in the treatment of uncomplicated superficial skin infections in our community at this time.

Sporotrichosis presenting as arthritis and subcutaneous nodules.

Arthritis is a rare manifestation of systemic sporotrichosis. A patient who had sporotrichal arthritis of both wrists and elbows is described. Predisposing factors included alcoholism, rose gardening, and antecedent trauma. The onset of the arthritis was insidious, and the diagnosis was made 2 1/2 years after his first symptoms were noted. Treatment with surgical debridement and a 23-week course of ketoconazole was unsuccessful. A review of the literature suggests that some combination of intravenous or intraarticular amphotericin B and potassium iodide, ketoconazole, or surgery is necessary for effective treatment.

Cutis verticis gyrata.

When the scalp exhibits folds and furrows resembling gyri, it is termed cutis verticis gyrata. The possible etiologies may be categorized as primary essential, primary nonessential, and secondary cutis verticis gyrata. This is based on history, physical examination, and histologic criteria with or without laboratory examinations.

Thrombotic vasculopathy associated with cryofibrinogenemia.

Cryofibrinogenemia refers to the presence of cold-precipitable plasma proteins associated with a variety of disorders, including malignancies, inflammatory processes, and thrombohemorrhagic phenomena. Few cases of essential or primary cryofibrinogenemia are reported. We report a case in a 48-year-old man of essential cryofibrinogenemia and hemorrhagic necrosis of the ears and of the upper and lower extremities. Histopathologic studies demonstrated extensive eosinophilic thrombi in the dermal vasculature, with minimal inflammation and no vasculitis. Cryofibrinogenemia should be considered in the investigation of patients with otherwise unexplained cold intolerance and dermal thrombosis associated with minimal or no inflammation.