1. Which fungal strain is the most common cause of tinea capitis in the United Kingdom and North America?
a. Trichophyton tonsurans
b. Microsporum audouinii
c. Trichophyton rubrum
d. Microsporum canis
2. What percentage of cells in the epidermis are keratinocytes?
a. 50%
b. 65%
c. 80%
d. 95%
3. Which of the following conditions is inherited in X-linked fashion?
a. Tuberous sclerosis
b. Incontinenta pigmenti
c. Ataxia telangiectasia
d. Neurofibromatosis
4. What does the Greek root of the term "ichthyosis" mean?
a. Fish
b. Crocodile
c. Elephant
d. Lizard
5. Lichen striatus most commonly occurs in which anatomic location?
a. Face
b. Chest
c. Abdomen
d. Extremities
6. Which of the following conditions is characterized by intraepidermal blistering?
a. Bullous pemphigoid
b. Porphyria cutanea tarda
c. Herpesvirus infection
d. Dermatitis herpetiformis
7. What is the mechanism of action of injectable local anesthetics?
a. Blockage of potassium channels
b. Inhibition of cyclooxygenase
c. Blockage of sodium channels
d. Inhibition of prostaglandins
8. Which of the following statements most accurately describes pemphigus vulgaris?
a. Onset is most common in the third and fourth decades of life.
b. Initial lesions generally occur on the trunk.
c. Auspitz sign is usually positive.
d. Untreated disease is commonly fatal.
9. What does the term "acantholysis" refer to on a dermatopathology report?
a. Loss of intercellular connections
b. Reduced thickness of the granular layer
c. Abnormal retention of keratinocyte nuclei
d. Intercellular edema
10. Approximately what percentage of untreated syphilis cases progressed to tertiary syphilis?
a. 15%
b. 33%
c. 66%
d. 85%
ANSWERS
1. a. Trichophyton tonsurans. In the United Kingdom and North America, Trichophyton tonsurans accounts for more than 90% of tinea capitis cases. Occasionally, cases of tinea capitis are related to pet exposure, in which case Microsporum canis is generally the responsible fungal strain. Tinea capitis may also be caused by any other pathogenic dermatophytes, except for Epidermophyton floccosum and Trichophyton concentricum.
James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier.
Kao, G. F. (2014). Tine capitis. Retrieved from http://emedicine.medscape.com/article/1091351-overview#a6
2. c. 80%. At least 80% of cells in the epidermis are ectodermally derived keratinocytes. Keratinocytes synthesize keratin, a long, threadlike protein with a protective role. The term keratinization refers to the differentiation process that occurs as the cells migrate from the basal layer to the surface of the skin. During this process, the keratinocytes first pass through a synthetic and then a degradative phase. The epidermis commonly is divided into four layers according to keratinocyte morphology and position as they differentiate and rise to the surface. The cells begin in the basal cell layer (stratum germinativum), then rise to the squamous cell layer (stratum spinosum), then the granular cell layer (stratum granulosum), and finally, the cornified or horny cell layer (stratum corneum) before being shed into the environment. In addition to keratinocytes, the epidermis harbors a number of other cell populations, such as melanocytes, Langerhans cells, and Merkel cells.
Kolarsick, P.A. J., Kolarsick, M. A., & Goodwin, C. (2011). Anatomy and physiology of the skin. Journal of the Dermatology Nurses' Association, 3(4), 203-213.
3. b. Incontinenta pigmenti. Incontinenta pigmenti is an X-linked dominant condition that appears in girls during the first weeks after birth. In most cases, vesicular and verrucous lesions occur before the onset of spattered pigmentation on the trunk. The pigmentation occurs in the form of macules arranged in streaks, sprays, splatters, and whorls that follow the lines of Blaschko. Tuberous sclerosis is an autosomal-dominantly inherited condition in which affected individuals may experience adenoma sebaceum, mental deficiency, and epilepsy. Cutaneous manifestations include periungual fibromas, shagreen plaques, oral papillomatosis, ash-leaf hypomelanotic macules, skin fibromas, and cafe au lait spots. Ataxia telangiectasia is a rare autosomal recessive disorder in which affected individuals experience neurologic decline that usually results in wheelchair dependency in the early teenage years. Cutaneous manifestations include telangiectasias, cafe au lait patches, hypopigmented macules, seborrheic dermatitis, premature graying, and sparsity of the hair and progeroid features. Neurofibromatosis is an autosomal-dominantly inherited syndrome manifested by developmental changes in the nervous system, bones, and skin. Cutaneous manifestations of neurofibromatosis include cafe au lait macules, neurofibromas, and freckling in the axillary or inguinal regions.
James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier.
4. a. Fish. The term "ichthyosis" is derived from the Greek root "ichythys," which means fish. The most common form of ichthyosis is ichthyosis vulgaris, which is also called "fish scale disease" or "fish skin disease." Clinically, ichthyosis vulgaris is characterized by excessively dry, scaly skin.
New Zealand Dermatological Society Incorporated. (2015). Ichthyosis vulgaris. Retrieved from http://www.dermnetnz.org/scaly/ichthyosis-vulgaris.html
5. d. Extremities. Lichen striatus is a fairly common, self-limited eruption that is seen primarily in children. Involvement of an extremity is most common, although lesions can occasionally occur on the trunk, head, or neck. Lesions begin as 1- to 3-mm papules that are erythematous and slightly scaly. These papules coalesce to form a 1- to 3-cm-wide continuous or interrupted band that, over a few weeks, progresses down the extremity following the lines of Blaschko. The lesions are usually asymptomatic and last for an average of 1 year before spontaneously resolving.
James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier.
6. c. Herpesvirus infection. Herpesvirus infections are characterized by blistering in the spinous layer of the epidermis. The other three conditions listed are characterized by blistering at the dermal-epidermal junction. More specifically, bullous pemphigoid blisters at the lamina lucida, whereas porphyria cutanea tarda and dermatitis herpetiformis blister below the basal lamina.
Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.
7. c. Blockage of sodium channels. Local anesthetics exert their influence on nerves by blocking the sodium channels on nerve axons. This blockage inhibits depolarization and the formation of an action potential. Because local anesthetics affect the smaller unmyelinated C-type nerve fibers more rapidly and effectively than myelinated A-type nerve fibers, adequate anesthesia can be achieved while motor function and pressure sensation are maintained.
Goldsmith, L. A., Katz, S. I., Gilchrest, B. A., Paller, A. S., Leffell, D. J., & Wolff, K. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York, NY: McGraw-Hill Medical.
Roenigk, R. K., Ratz, J. L., & Roenigk, H. H. (2007). Roenigk's dermatologic surgery: Current techniques in procedural dermatology (3rd ed.). New York, NY: Informa Health Care.
8. d. Untreated disease is commonly fatal. Pemphigus vulgaris (PV) is a chronic blistering dermatosis that generally occurs in the fifth and sixth decades of life. The lesions of PV usually first appear in the mouth (60%) or at the site of a burn or other skin injury. Other common sites include the groin, scalp, face, neck, axillae, and genitals. PV occurs because of an autoimmune reaction, which triggers the formation of mucosal erosions and thin-walled, relatively flaccid, easily ruptured bullae that appear on apparently normal skin and mucous membranes or on erythematous bases. The fluid in the bullae is clear at first but may become hemorrhagic or even seropurulent. The bullae rupture to form erosions, and the denuded areas soon become partially or totally covered with crusts that have little or no tendency to heal. Nikolsky sign is present (twisting or rubbing causes intact epidermis to shear away from the underlying dermis leaving a moist surface) as is Asboe-Hansen sign (gentle pressure on an intact bullae forces the fluid to spread under the adjacent skin). Auspitz sign refers to the appearance of pinpoint areas of bleeding when scale is removed from psoriatic plaques and is not associated with PV. Management of PV involves symptomatic treatment of the wounds with topical agents as well as the use of systemic immunosuppressive medications such as prednisone, mycophenolate mofetil, or azathioprine. Prompt diagnosis and treatment leads to a more favorable prognosis, and untreated disease is commonly fatal. However, in treated patients, the most common cause of death is medication side effects. Treatment is continued until clinical disease is suppressed and pemphigus antibodies disappear from the serum.
James, W. D., Berger, T. G., & Elston, D. M. (2011). Andrews' diseases of the skin: Clinical dermatology (11th ed.). Philadelphia, PA: Saunders/Elsevier.
9. a. Loss of intercellular connections. Acantholysis is the loss of cohesion between keratinocytes because of dissolution of intercellular connections, sometimes resulting in an intraepidermal vesicle. Acanthocyte is an old name for keratinocyte and means "prickle cell," referring to the desmosomal spines that normally connect the cells. Acantholysis differs from the intercellular edema of spongiosis in that acantholytic keratinocytes tend to be rounded rather than elongated, the desmosomal spines appear destroyed rather than stretched, and exocytosis of lymphocytes into the epidermis is usually absent. Conditions in which acantholysis is present include Darier's disease, Hailey-Hailey disease, all varieties of pemphigus, Grover's disease, herpes virus infections, staphylococcal scalded skin syndrome, and warty dyskeratoma.
Bolognia, J. L., Jorizzo, J. L., & Schaffer, J. V. (2012). Dermatology (3rd ed.). St. Louis, MO: Elsevier/Mosby.
Rapini, R. P. (2012). Practical dermatopathology (2nd ed.). Philadelphia, PA: Elsevier Saunders.
10. b. 33%. About 33% of untreated syphilis cases progress to tertiary (late) syphilis. Another 33% of untreated cases are arrested by the host, and the serum rapid plasma reagin (RPR) becomes negative. In the final third of untreated cases, the serum RPR remains positive, but the disease does not progress during the patient's lifetime. The symptoms of tertiary syphilis can occur months or years after infection and result from the Treponema pallidum microorganisms invading the central nervous system, cardiovascular system, skin, and other organs. Damage then occurs because of host delayed-hypersensitivity responses, which produce local inflammation and gummas (locally destructive lesions) in affected tissues.
Bolognia, J. L., Jorizzo, J. L., & Schaffer, J. V. (2012). Dermatology (3rd ed.). St. Louis, MO: Elsevier/Mosby.