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Questions and Answers
Which layer of the skin contains the stratum corneum?
Which layer of the skin contains the stratum corneum?
Which layer of the skin accounts for skin tone and the strength of the skin?
Which layer of the skin accounts for skin tone and the strength of the skin?
Which skin layer holds hair follicles and sebaceous glands?
Which skin layer holds hair follicles and sebaceous glands?
Where is the subcutaneous tissue located?
Where is the subcutaneous tissue located?
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What structures are included in skin appendages?
What structures are included in skin appendages?
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Which skin layer contains specialized structures such as sweat glands and erector muscles?
Which skin layer contains specialized structures such as sweat glands and erector muscles?
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Where is the tough horny superficial layer of the skin located?
Where is the tough horny superficial layer of the skin located?
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What does the subcutaneous tissue mainly consist of?
What does the subcutaneous tissue mainly consist of?
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What is the primary risk factor associated with pityriasis versicolor?
What is the primary risk factor associated with pityriasis versicolor?
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Which region shows a lower incidence of pityriasis versicolor?
Which region shows a lower incidence of pityriasis versicolor?
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What is the characteristic color of the macular lesions in pityriasis versicolor for dark-skinned people?
What is the characteristic color of the macular lesions in pityriasis versicolor for dark-skinned people?
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What is the primary method for diagnosing pityriasis versicolor?
What is the primary method for diagnosing pityriasis versicolor?
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What is the first-line treatment for pityriasis versicolor?
What is the first-line treatment for pityriasis versicolor?
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What is the characteristic appearance of mature nodules of Malassezia on the hair shaft?
What is the characteristic appearance of mature nodules of Malassezia on the hair shaft?
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What is the characteristic morphology of Malassezia when observed under a microscope?
What is the characteristic morphology of Malassezia when observed under a microscope?
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Which environmental factor favors the growth of Malassezia?
Which environmental factor favors the growth of Malassezia?
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What is the primary site for infection by Malassezia?
What is the primary site for infection by Malassezia?
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Which test is used for diagnosing Tinea nigra?
Which test is used for diagnosing Tinea nigra?
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What is the primary method for diagnosing Tinea nigra?
What is the primary method for diagnosing Tinea nigra?
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What is the superficial layer of the skin consisting of dead skin cells?
What is the superficial layer of the skin consisting of dead skin cells?
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Which layer of the skin contains a lot of specialized structures such as hair follicles, sweat glands, arteries, and afferent nerve endings?
Which layer of the skin contains a lot of specialized structures such as hair follicles, sweat glands, arteries, and afferent nerve endings?
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What is the function of sweat glands in the skin?
What is the function of sweat glands in the skin?
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Where is subcutaneous tissue located?
Where is subcutaneous tissue located?
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What is the causative agent of tinea nigra?
What is the causative agent of tinea nigra?
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What leads to the transition of Malassezia to its mycelial form and invasion of stratum corneum?
What leads to the transition of Malassezia to its mycelial form and invasion of stratum corneum?
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What triggers inhibition of melanin synthesis in tinea versicolor causing hypopigmentation?
What triggers inhibition of melanin synthesis in tinea versicolor causing hypopigmentation?
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Where is Malassezia furfur found in nature?
Where is Malassezia furfur found in nature?
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What does Malassezia furfur rely on for its survival?
What does Malassezia furfur rely on for its survival?
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What is the characteristic feature of tinea versicolor?
What is the characteristic feature of tinea versicolor?
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What causes infection after trauma to the skin by Malassezia furfur?
What causes infection after trauma to the skin by Malassezia furfur?
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What triggers inflammation resulting in erythematous skin in tinea versicolor?
What triggers inflammation resulting in erythematous skin in tinea versicolor?
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Pityriasis versicolor is characterized by patches of which of the following?
Pityriasis versicolor is characterized by patches of which of the following?
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What is the causative agent of pityriasis versicolor?
What is the causative agent of pityriasis versicolor?
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What are the risk factors for pityriasis versicolor?
What are the risk factors for pityriasis versicolor?
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How is diagnosis of pityriasis versicolor typically made?
How is diagnosis of pityriasis versicolor typically made?
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What is the color of lesions under Wood lamp examination for pityriasis versicolor?
What is the color of lesions under Wood lamp examination for pityriasis versicolor?
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Which statement about pityriasis versicolor treatment is accurate?
Which statement about pityriasis versicolor treatment is accurate?
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Which is the causative agent of Tinea Nigra?
Which is the causative agent of Tinea Nigra?
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What is the incubation period for Tinea Nigra after skin trauma?
What is the incubation period for Tinea Nigra after skin trauma?
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Where does Tinea Nigra infection occur?
Where does Tinea Nigra infection occur?
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Which area does Piedra (Trichomycosis nodularis) affect?
Which area does Piedra (Trichomycosis nodularis) affect?
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What is the causative agent of White Piedra?
What is the causative agent of White Piedra?
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What is the appearance of White Piedra on hair shaft?
What is the appearance of White Piedra on hair shaft?
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Which agar is used for culture in Tinea Nigra diagnosis?
Which agar is used for culture in Tinea Nigra diagnosis?
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What type of fungal infection is Piedra (Trichomycosis nodularis)?
What type of fungal infection is Piedra (Trichomycosis nodularis)?
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What is the appearance of Black Piedra on hair shaft?
What is the appearance of Black Piedra on hair shaft?
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What does Tinea nigra look like under a Wood Lamp Examination with 10-15% KOH?
What does Tinea nigra look like under a Wood Lamp Examination with 10-15% KOH?
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What type of transmission is rare in Tinea Nigra?
What type of transmission is rare in Tinea Nigra?
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Which topical treatment can be used for Tinea Nigra?
Which topical treatment can be used for Tinea Nigra?
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Study Notes
- Wood Lamp Examination (Direct Examination): 10-15% KOH - Presence of hyphal and yeast forms, resemble a "spaghetti-and-meatballs" appearance.
- Tinea Nigra:
- Caused by Hortaea werneckii, a dematiaceous fungus.
- Infection occurs after trauma to the skin, with an incubation period of 2-7 weeks.
- Infection is confined in the stratum corneum with no disfiguration, and can be asymptomatic and non-pruritic.
- Occurs in tropical or subtropical areas, with a low incidence in the USA and Europe but associated with tropical travel.
- Person-to-person transmission is rare, and there is a female-to-male predilection.
- Macular Lesion caused by Tinea nigra: Figure 5.
- Diagnosis of Tinea nigra:
- Microscopic examination of skin scrapings with KOH - brown or black septate hyphae, oval-to-spindle-shaped yeast cells.
- Culture on Sabouraud dextrose agar (SDA) - definitive diagnosis, growth visible within one week.
- Tinea nigra is not caused by Malassezia.
- Treatment for Tinea nigra:
- Topical treatments: shampoos (pyrithione zinc or selenium sulfide), propylene glycol in aqueous solution, keratolytic (Whitfield ointment), topical imidazoles (ketoconazole).
- Second line (oral) treatments: topical antifungal, oral fluconazole, systemic antifungals (rarely indicated).
- Piedra (Trichomycosis nodularis) is an asymptomatic superficial fungal infection of the hair shaft with characteristic white or black nodules attached to the hair shaft.
- Piedra occurs in temperate and semitropical climates and affects scalp hair.
- Piedra is caused by various dematiaceous etiologic agents, which are found in soil, stagnant water, and crabs.
- White Piedra:
- Softer, less adherent to hair shaft.
- Causative agent is Trichosporon asahii, other body surfaces.
- Appears as white or brown compressions on hair shaft.
- Growth occurs in a hyphal form, which can fragment into component buds, or as branched hyphae.
- Black Piedra:
- Firmer, more adherent to hair shaft.
- Causative agent is T. ovoides, scalp.
- Appears as black compressions on hair shaft.
- Growth occurs in a hyphal form, which fragments into closely aligned fungal arthrospores or as ascus.
- Culture: Sabouraud dextrose agar, does not require cycloheximide for growth (Sabouraud Dextrose Agar), takes long to culture (Sabouraud Dextrose Agar), resembles colonies of Tinea nigra.
- Shaving infected hair or curative treatment + topical azole + systemic antifungal agent (i.e. oral itraconazole) due to high relapse rates.
- Review Questions:
- The layer of the skin that contains the sweat glands is: d. Skin appendages.
- The type of primary skin lesions that can be erythematous, pruritus is: b. Wheal.
- TRUE OR FALSE: Scales are accumulations of thickened stratum corneum - True.
- In Tinea nigra, infection can spread to other parts of the body - False.
- The male-to-female predilection in Tinea nigra is 3:1 - False.
- Microscopic examination of skin scrapings in Tinea nigra is with __% KOH - 10%.
- White piedra occurs in the frontal area of scalp - False.
- The definitive diagnosis of Tinea nigra is: a. Culture on SDA with cycloheximide and chloramphenicol additive - False.
- Malassezia lacks: a. Tyrosinase - False.
- Pityriasis veriscolor is caused by an undergrowth of Malassezia furfur - False.
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Description
Test your knowledge of dermatology with this quiz on the examination and culture of wood lamp and skin lesions caused by fungal infections such as tinea nigra. Identify the characteristic features and diagnostic procedures.
