Discussion in 'Spot Diagnosis' started by bb100, Apr 13, 2013.
what is this disease ?
Re: dermatologic cases
Pitryiasis versicolor (aka Tinea versicolor aka Dermatomycosis furfuracea aka Tinea flaveaaka Liver spots aka Chromophytosis) caused by M furfur.
Disclaimer: my initial impression ( Differentials ) was - Guttate psoriasis, Pityriasis rosea and Sec. syphylis ( rash of which can mimic P. rosea ), becos of the white scaly nature of the lesions( scales of P versicolor r generally a little more dusky )...but, although the image is not very sharp, i cud not discern any inflammation surrounding the lesions and so i went 4 P versicolor.
points in favor (in general while making a diagnosis) -
1) it's versicolor i.e areas of hyper and hypopigmentation, let's call it dyspigmentation. Hypopigmentation has been attributed to azaleic acid produced by Malassezia species which causes competitive inhibition of tyrosinase and perhaps a direct cytotoxic effect on melanocytes. The cause for hyperpigmentation is not clear ( electron microscope - shows large melanosomes in hyperpigmented lesions and a thicker keratin layer ).
2) hardly any inflammation
( the other differentials i.e Seborrhoeic dermatitis, Pityriasis rosea, and Tinea corporis will have some visible inflammation esp. for such wide involvement ).
additional evidence in the form of dusky-white scaling (under good light and magnification ) can be seen in P versicolor and it can be accentuated by scratching with a glass slide and helps to differentiate it from vitiligo and chloasma.
Who is vulnerable ?
The adolescent age group ( reasons same as acne ).
Additionally in the tropics the farm laborers or others who work for long hours under the punishing tropical sun and wear tight undershirt / vest are particularly prone ( mechanism is easy to guess )
there is another population that is vulnerable - if somebody presents with asthenia and has multiple dermatoses +/- oral candidasis +/- lymphadenopathy , then think of HIV.
how to differentiate it from vitiligo ?
gently scrape it and then look carefully with a magnifying glass in good light ( light that mimicks daylight )....u will see fine scales. This is called the 'scratch sign' or 'Besnier's sign'
Occassionally, lesions may be variously colored as reddish brown, dark brown or black and hence the name versicolor i.e variously colored.
under wood's lamp they would fluoresce - golden yellow
....can't help it, that's what the books say P:
scraping the scales and then mounting in 10 % KOH is more than enough to confirm the diagnosis
'spaghetti and meatballs' appearance
spaghtti = hyphae and meatballs = spores
Now the above specimen is stained with PAS, but u can see it without staining as well....just scrape the lesion, with a glass slide, then stick a cello tape over the lesion, pour some kOH over a glass slide and stick the cello tape over it (it now contains the scales from the lesion) and observe under microscope
Prescribe topical ketoconazole body shampoo and call back in 3 weeks. Also advice loose clothing...if lesions persist after 3 weeks, then systemic antifungals.
Correct Answer :Tinea Versicolor (synonym : Dermatomycosis furfuracea, Pityriasis versicolor, Tinea flava)
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