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Dermatology Fungal Infection Test
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Dermatology Fungal Infection Test

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Questions and Answers

Which layer of the skin contains the stratum corneum?

  • Dermis
  • Subcutaneous Tissue
  • Epidermis (correct)
  • Skin Appendages

    • Which layer of the skin accounts for skin tone and the strength of the skin?

  • Epidermis
  • Skin Appendages
  • Dermis (correct)
  • Subcutaneous Tissue

    • Which skin layer holds hair follicles and sebaceous glands?

  • Dermis (correct)
  • Epidermis
  • Subcutaneous Tissue
  • Skin Appendages

    • Where is the subcutaneous tissue located?

    <p>Below the dermis</p> Signup and view all the answers

    What structures are included in skin appendages?

    <p>Hairs, glands, nails</p> Signup and view all the answers

    Which skin layer contains specialized structures such as sweat glands and erector muscles?

    <p>Dermis</p> Signup and view all the answers

    Where is the tough horny superficial layer of the skin located?

    <p>Epidermis</p> Signup and view all the answers

    What does the subcutaneous tissue mainly consist of?

    <p>Loose connective tissue and stored fat</p> Signup and view all the answers

    What is the primary risk factor associated with pityriasis versicolor?

    <p>Heavy sweating</p> Signup and view all the answers

    Which region shows a lower incidence of pityriasis versicolor?

    <p>USA and Europe</p> Signup and view all the answers

    What is the characteristic color of the macular lesions in pityriasis versicolor for dark-skinned people?

    <p>Hypopigmented</p> Signup and view all the answers

    What is the primary method for diagnosing pityriasis versicolor?

    <p>Microscopic examination of skin scrapings with 10% KOH</p> Signup and view all the answers

    What is the first-line treatment for pityriasis versicolor?

    <p>(Topical) Shampoos (pyrithione zinc or selenium sulfide)</p> Signup and view all the answers

    What is the characteristic appearance of mature nodules of Malassezia on the hair shaft?

    <p>Attached and more adherent to hair</p> Signup and view all the answers

    What is the characteristic morphology of Malassezia when observed under a microscope?

    <p>Branched hyphae in the hair shaft</p> Signup and view all the answers

    Which environmental factor favors the growth of Malassezia?

    <p>Warm and humid climate</p> Signup and view all the answers

    What is the primary site for infection by Malassezia?

    <p>Neck, chest, back, upper arms, scalp, abdomen, groin area</p> Signup and view all the answers

    Which test is used for diagnosing Tinea nigra?

    <p>Wood Lamp Examination</p> Signup and view all the answers

    What is the primary method for diagnosing Tinea nigra?

    <p>Culture on SDA with cycloheximide and chloramphenicol</p> Signup and view all the answers

    What is the superficial layer of the skin consisting of dead skin cells?

    <p>Stratum corneum</p> Signup and view all the answers

    Which layer of the skin contains a lot of specialized structures such as hair follicles, sweat glands, arteries, and afferent nerve endings?

    <p>Dermis</p> Signup and view all the answers

    What is the function of sweat glands in the skin?

    <p>Thermoregulation</p> Signup and view all the answers

    Where is subcutaneous tissue located?

    <p>Between dermis and deep fascia</p> Signup and view all the answers

    What is the causative agent of tinea nigra?

    <p>Hortaea werneckii</p> Signup and view all the answers

    What leads to the transition of Malassezia to its mycelial form and invasion of stratum corneum?

    <p>&quot;Human host’s hydrolysis of sebum triglyceride&quot;</p> Signup and view all the answers

    What triggers inhibition of melanin synthesis in tinea versicolor causing hypopigmentation?

    <p>Azelaic acid</p> Signup and view all the answers

    Where is Malassezia furfur found in nature?

    <p>Soil, sewage, decaying vegetation</p> Signup and view all the answers

    What does Malassezia furfur rely on for its survival?

    <p>Human host’s hydrolysis of sebum triglyceride</p> Signup and view all the answers

    What is the characteristic feature of tinea versicolor?

    <p>Brown to black macular lesions</p> Signup and view all the answers

    What causes infection after trauma to the skin by Malassezia furfur?

    <p>2-7 weeks after trauma due to early colonization in infants</p> Signup and view all the answers

    What triggers inflammation resulting in erythematous skin in tinea versicolor?

    <p>Free fatty acid from hydrolysis of triglyceride</p> Signup and view all the answers

    Pityriasis versicolor is characterized by patches of which of the following?

    <p>Hypopigmentation or hyperpigmentation</p> Signup and view all the answers

    What is the causative agent of pityriasis versicolor?

    <p>Malassezia furfur</p> Signup and view all the answers

    What are the risk factors for pityriasis versicolor?

    <p>Tropical climate, heavy sweating, and immunosuppression</p> Signup and view all the answers

    How is diagnosis of pityriasis versicolor typically made?

    <p>Distinctive morphology of the lesions or dermoscopy</p> Signup and view all the answers

    What is the color of lesions under Wood lamp examination for pityriasis versicolor?

    <p>Pale yellow-green</p> Signup and view all the answers

    Which statement about pityriasis versicolor treatment is accurate?

    <p>Easily treatable with antifungal agents but relapse is common</p> Signup and view all the answers

    Which is the causative agent of Tinea Nigra?

    <p>Hortaea werneckii</p> Signup and view all the answers

    What is the incubation period for Tinea Nigra after skin trauma?

    <p>2-7 weeks</p> Signup and view all the answers

    Where does Tinea Nigra infection occur?

    <p>Stratum corneum</p> Signup and view all the answers

    Which area does Piedra (Trichomycosis nodularis) affect?

    <p>Scalp hair</p> Signup and view all the answers

    What is the causative agent of White Piedra?

    <p>Trichosporon asahii</p> Signup and view all the answers

    What is the appearance of White Piedra on hair shaft?

    <p>White compressions</p> Signup and view all the answers

    Which agar is used for culture in Tinea Nigra diagnosis?

    <p>Sabouraud dextrose agar (SDA)</p> Signup and view all the answers

    What type of fungal infection is Piedra (Trichomycosis nodularis)?

    <p>Superficial infection of the hair shaft</p> Signup and view all the answers

    What is the appearance of Black Piedra on hair shaft?

    <p>Black compressions</p> Signup and view all the answers

    What does Tinea nigra look like under a Wood Lamp Examination with 10-15% KOH?

    <p>Spaghetti-and-meatballs appearance</p> Signup and view all the answers

    What type of transmission is rare in Tinea Nigra?

    <p>Person-to-person transmission</p> Signup and view all the answers

    Which topical treatment can be used for Tinea Nigra?

    <p>Pyrithione zinc shampoo</p> Signup and view all the answers

    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.

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