Question
Vitiligo and tinea versicolor are both hypomelanocytic dermatologic afflications. What are some ways to differentiate these two conditions?
Answer
Langer’s Lines
Other known aliases – Langer’s lines of skin tension, cleavage lines
Definition – topographical lines on the human body that correspond to the natural orientation of the collagen fibers of the dermis and are parallel to the orientation of the underlying muscle fibers
Clinical Significance – Incisions made on the skin that run parallel with these lines produce much less tension on the wound, heal better with less scarring, and have a much better cosmetic appearance. This is important in cosmetic surgery applications, as well as elective surgical procedures when you can select where to make your incision.
History – Named after Karl Langer (1819-1887), an Austrian anatomist, who received his medical doctorate from the Universities of Vienna and Prague. He worked under Joseph Hyrtl as a prosector for the University of Vienna and later becoming the director in 1874. In his famous procedure discovering these tension lines, he punctured circular holes on the skin of cadavers and noticed that they would result in ellipisoidal wounds. By following the direction of these ellipses, he was able to topographically map these lines on the entire body. He did give credit to Baron Dupuytren as being the first to observe this phenomenon and published his findings in 1861 entitled “Zur Anatomie und Physiologie der Haut. Über die Spaltbarkeit der Cutis”
References
Question
Vitiligo and tinea versicolor are both hypomelanocytic dermatologic afflications. What are some ways to differentiate these two conditions?
What are the 5 things to assess in a suspicious lesion/mole to evaluate for melanoma?
The ABCDEs of melanoma will help you identify suspicious lesions that will need dermatologic follow-up
Asymmetry
Border Irregularity
Color
Diameter
Evolution
The is also another set of criteria that was developed in the UK by the United Kingdom National Institute for Clinical Excellence (NICE) and by the Scottish Intercollegiate Guidelines Network called the Glasgow Seven-point Checklist. These guidelines incorporate 3 major and 4 minor criteria and any major or 3 minor criteria is an indication for referral.
Major
Minor
Once a patient has been referred to a dermatologist, they use a similar seven point system on dermoscopy to diagnose melanoma.
Major (2 points each)
Minor (1 point each)
A melonoma score of ≥ 3 is required for diagnosis
Melanoma – http://www.dermoscopy.org/consensus/2d.asp
Melanoma – http://www.dermoscopy.org/consensus/2d.asp
Clark nevus – http://www.dermoscopy.org/consensus/2d.asp
References
Other Known Aliases – Ultraviolet (UV)-A lamp, blacklight
Definition – Handheld UV light that emits UV-A (long-wave) light with a violet filter, which blocks most of the visible light, and only allows the UV-A through
Clinical Significance – There are many medical applications for using UV light for quick, bedside diagnosis. One of these is for fungal infections of the skin, most commonly Tinea infections. Tinea infections will fluoresce under UV-A light.
Tinea versicolor
Tinea capitis
History – Named after Robert W. Wood (1868-1955), who was an American physicist, inventor, and a pioneer in infrared and ultraviolet photography. In 1903, he developed a filter that would block visible light, but be transparent to both infrared and ultraviolet light. He won several awards and honors in the field of optics (he even has a crater on the moon named after him) and is the namesake of the R.W. Wood Prize of the Optical Society of America, which recognizes outstanding discovery, achievement, or invention.
References
What are the 5 things to assess in a suspicious lesion/mole to evaluate for melanoma?
Vector
Sarcoptes scabiei
Scabies is caused by the mite Sarcoptes scabiei, which is a whitish-brown, eight-legged mite and it just barely visible by the naked eye at its largest size of 0.4×0.3mm. Only the female mite causes the dermatologic manifestations seen in scabies, as it burrows into the epidermis down to the stratum granulosum layer to lay her eggs.
The female mite can grow these burrows up to 2mm per day and lay 2-3 eggs, up to a total of 10-25 eggs. These eggs hatch after 3-4 days, molt multiple times, and burrow to the surface to mate and then return to continue this viscous cycle. Typically, incubation takes 3-6 weeks after infestations until symptoms present.
Transmission
Scabies are transmitted from direct contact with an infected person and most commonly is sexually acquired. Although not as common, transmission has also been reported to occur through contaminated clothing or bedding as these mites can survive off a host for up to 24-36 hours. Animals can contract scabies, but these rarely cause disease in humans, as they do not reproduce on human hosts.
Risk Factors
Signs and Symptoms
The typically manifestation of scabies is an intensely pruritic rash that is worse at night. The lesions of the rash are small, erythematous, papules typically with an excoriated, hemorrhagic crust. The burrows that may be seen are thin gray/brown/red lines up to 20mm in length.
Areas most common infected are:
Head, face, and back are not commonly seen and this is theorized to be due to the increased oil production in these areas.
Crusted (Norwegian) Scabies
Immunocomprimised, eldery, debilitated, or disabled patients are at increased risk of developing this severe form of scabies. These mites are not more virulent, but because of their underlying medical conditions, the concentration of mites is much more numerous. These patients develop thick crusts and are highly contagious due to the overwhelming contamination.
Diagnosis
This should be a diagnosis of history and physical exam alone. Skin scrapings can visualize the mites or eggs under the microscope.
Dermoscopy can be used to see the mite in burrow and is classically referred to as the “delta wing” sign, which is the dark head of the mite at the end of a burrow.
“delta wing” sign
Treatment
Prevention of Re-infestation
Recommendations are for all close-contact household members to be treated simultaneously, even if asymptomatic, to prevent cross contamination and re-infestation. Patients should be instructed to wash all clothing/bedding on the hot water cycle with high heat drying to kill any mites. Stuffed animals, jackets, or any other objects not feasible to wash, can be isolated in a plastic bag for 3 days. Fumigation is not necessary
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