DERMATOLOGY EXAM MASTER QUESTIONS AND ANSWERS 2022 LATEST UPDATE

DERMATOLOGY EXAM MASTER QUESTIONS AND ANSWERS 2022 LATEST UPDATE Case A 20-year-old Caucasian woman presents to the hospital with a 2-month history of itchiness of her scalp. On examination you note greasy yellowish scales on her scalp and eyebrows. Question What is the most likely diagnosis?Correct answer: Seborrheic dermatitis Explanation This patient most probably has seborrheic dermatitis. Itis characterized by greasy scales over the scalp. It may also be visible along the hairline, on the eyebrows, in the external auditory canals, in the nasolabial folds, and over the sternum. There may be some pruritus. Hand eczema is characterized by erythema, dryness, cracking, and edema of the skin of the hands. It is a chronic condition, which is aggravated by frequent immersion of hands in water and detergents. Atopic dermatitis is characterized by chronic pruritic lesions marked by exacerbations and remissions. There is a personal or family history of asthma, allergic rhinitis, food allergies, or eczema. In the acute phase, they may present with erythematous patches, weeping, and crusted plaques. In the chronic phase, they present with hyperpigmented lichenified lesions. It commonly affects the face, neck, wrists, antecubital, and popliteal fossae. Nummular dermatitis is characterized by chronic coin-shaped, crusted lesions, which are usually pruritic. They commonly appear on the trunk and extensor surfaces of the extremities, especially the pretibial areas. Pompholyx is characterized by scaling and deep-seated vesicles on the palms, fingers, and soles, which are pruritic. There may also be erythema and scaling. Case A 7-year-old boy presents with a 3-day history of intense pruritus on his wrists, fingers, and antecubital fossae. It began on his fingers and has moved proximally. According to his mother, they are raised red eruptions and some have scabbed over. She states he has never had this before and it is keeping him up at night. He recently started at a new school. Question What procedure would be most helpful in confirming your diagnosis?Correct answer: Skin scraping with immersion oil Explanation Skin scraping with immersion oil is the confirmatory test for scabies, which is the most likely diagnosis. Wood lamp inspection consists of shining ultraviolet light on the skin, looking for fluorescence indicative of such diseases as erythrasma, fungal infections, and sclerosis. Skin scraping with KOH is helpful in diagnosing fungal infections of the skin. Punch biopsies are more invasive, and they are used for deeper skin lesions. Skin culture and Gram stain are not helpful in the diagnosis of scabies; they are used for suspected bacterial or fungal infections. Question A 23-year-old man presents with unbearable itching in his genital area. The itching increases in intensity at night. He admits to several recent sexual encounters with different people in the past month. Skin exam reveals multiple excoriated papules and burrows with surrounding inflammation. What is the most likely diagnosis?Correct answer: Scabies Explanation The correct answer is scabies because intense pruritis, especially at night, with excoriated papules and characteristic burrows or raised tunnels under the skin are a typical presentation. Tinea cruris is a fungal infection and can also be intensely pruritic but does not cause the dermatologic manifestations noted above. Pediculosis pubis, an arthropod, is another cause of pruritis but does not cause the dermatologic manifestations noted above, and typically the lice and their nits are seen on examination. Molluscum contagiosum and HPV are caused by viruses, are not pruritic lesions, and do not present as excoriated papules with burrows. Question A 15-year-old boy presents to the office with his mother with a complaint of constant itching and burning on his arms and thighs for 2 weeks. His mother admits to giving him acetaminophen without relief. The patient is taking no other medications. On clinical exam, there are multiple 2-cm wheals with a few small papules on his thighs and forearms. They are red and slightly raised. What is the most likely diagnosis?Correct answer: Urticaria Explanation Urticaria is chronic or acute and is characterized by wheals and papules. Itching and prickling sensations are constant. Both sexes are affected equally, and it's often seen in childhood or teen years. The presenting areas are the arms, legs, thighs, and waist. The most common cause is an allergy to medications, foods, or physical agents. The symptoms usually disappear within 6 months (acute), but they can last longer (chronic). Erythema nodosa is an acute inflammatory condition characterized by painful nodules on the anterior aspect of the legs. It is often symptomatic of a bacterial, viral, or fungal disease or drug eruption. This occurs most often in women and between the ages of 20 - 30 years. Clinical features include acute fever, malaise, and joint pain. Lesions are nodular, painful, red, and shiny. The symptoms last 2 weeks, and the lesions heal without scarring. Erythema multiforme is characterized by macules, papules, vesicles, and bullae. It occurs secondary to a toxic influence. There may or may not be a prodromal period with a sore throat, diarrhea, and fever. The lesions are red macules or papules and are seen on the sides of the neck, face, legs, genitalia, and mucosa membranes. A typical lesion is a "target" or "iris" lesion. The course is generally 3 - 4 weeks. Erythema ab igne, often called toasted skin syndrome, occurs secondary to exposure to heat from flames or heating appliances. The course is generally benign, but may have a potential for malignant changes. The lesions are red, mottled skin with hypo- or hyperpigmentation. After many years of constant exposure, hyperkeratotic papules, plaques, and ulcers may occur. Nummular eczema has round, coin-like (nummular) lesions with a distribution on the extensor surface of the extremities as well as the posterior portion of the trunk, buttock, and legs. Purulent drainage is not uncommon. Treatment includes topical steroids, systemic antibiotics, and antihistamines; decreasing exposure to water is recommended, and drying agents are used when oozing is present. Case A 23-year-old woman comes to the office for a gynecologic examination. This is her first visit, and she has no complaints. She tells you that she has not had a Pap smear in several years. Her menarche was at 12 years, and she has had regular cycles since then. She has had several sexual partners in the past, but has been with her current partner in a monogamous relationship for 1 year. She reports that she had a chlamydial infection that was treated several years ago, but she denies a history of other sexually transmitted diseases. She has never been pregnant. On physical examination, her cervix appears friable with a slight area of ulceration. There are several perineal and vaginal lesions, which appear as small cauliflowerlike projections. The results of the Pap smear, which return in 1 week, show a lowgrade squamous intraepithelial lesion (mild dysplasia, CIN I). Question What factor in this patient's case is most closely correlated with the abnormal finding on the Pap test?Correct answer: Condyloma acuminata Explanation A Pap smear should be obtained routinely during the pelvic examination at the initial visit. The Pap smear as a screening test has been extremely successful for the prevention of cervical cancer. Detection of dysplasia allows for successful treatment and prevention of cancer. Risk factors for cervical cancer include: Early age of first coitus Multiple sexual partners Immune suppression Low socioeconomic status Lack of Pap smear screening This patient has more than 1 risk factor at this young age. Condyloma acuminata are soft, fleshy warts that are caused by the HPV. Cervical dysplasia and carcinoma in situ are likely caused by types 16, 18, 31, 33, and 34. It is sometimes difficult to differentiate from squamous cell carcinoma. It is possible to treat these warts with a topical application if they are small in size. If they are large warts, cryotherapy may be required. Case A 20-year-old African-American woman presents with itchy rashes on her hands. She reports that they have been persistent for the past 2 years. On examination, deep-seated vesicles with scaling on her palms are noted bilaterally. Question Ico-delete Highlights What is the most likely diagnosis?Correct answer: Pompholyx Explanation This patient most probably has pompholyx. It is characterized by scaling and deepseated vesicles on the palms, fingers, and soles; the vesicles are pruritic. There may also be erythema and scaling. Atopic dermatitis is characterized by chronic pruritic lesions marked by exacerbations and remissions. There is a personal or family history of asthma, allergic rhinitis, food allergies, or eczema. In the acute phase, the dermatitis may present with erythematous patches, weeping, and crusted plaques. In the chronic phase, it presents with hyperpigmented lichenified lesions. It commonly affects the face, neck, wrists, antecubital, and popliteal fossae. Seborrheic dermatitis is characterized by greasy scales over the scalp. It may also be visible along the hairline, on the eyebrows, in the external auditory canals, in the nasolabial folds, and over the sternum. There may be some pruritus. Hand eczema is characterized by erythema, dryness, cracking, and edema of the skin of the hands. It is a chronic condition which is aggravated by frequent immersion of hands in water and detergents. Nummular dermatitis is characterized by chronic coin-shaped, crusted lesions which are usually pruritic. They commonly appear on the trunk and extensor surfaces of the extremities, especially the pretibial areas. Case A 32-year-old migrant worker presents because some of his toenails have changed color and have become brittle. You ask him to remove his shoes and socks; you note a yellow-brown discoloration of the first and fifth toenails. On closer exam, the toenails have become thickened and friable; there is debris under the nail distally. Question What is the most likely diagnosis?Correct answer: Tinea unguium Explanation The clinical picture is suggestive of Tinea unguium. Typical findings include subungual hyperkeratosis and yellow-brown discoloration with debris under the nail distally and laterally. When lichen planus affects the nail, it causes destruction of the nail fold and nail bed with longitudinal splintering, which is not seen in this patient. Acute paronychia is an acute infection of the lateral or proximal nail fold. Findings include throbbing pain, erythema, swelling, and pain. There may or may not be an abscess. These findings are not present in this patient. Tinea pedis is incorrect. Tinea pedis is tinea infection of the foot, also known as athlete's foot, and is characterized by itchy lesions and scaling in the interdigital spaces and on the soles of the feet. In onychomycosis caused by Candida, the entire nail bed is thickened and dystrophic, and it most commonly occurs on the fingernails and is associated with immunocompromise. Case A 66-year-old woman presents with a rash that has developed over the last 3 weeks; it has been getting worse. She states that her legs began to itch and became red with blisters, she noted that the same thing was occurring on her abdomen about 1 week ago. On physical examination, you note urticarial, inflammatory plaques, as well as papules with blister formation. On her abdomen, you note inflammatory plaques surmounted by tense blisters. Question What is your initial diagnosis?Correct answer: Bullous pemphigoid Explanation The clinical picture is suggestive of bullous pemphigoid. Bullous pemphigoid is an autoimmune disorder that affects the structural protein of the skin. Common occurrence is age 60-80, and it often appears on the lower legs. Initial symptoms include moderate to intense pruritus. The lesions are usually urticarial, papular, and erythematous; they evolve in weeks to months into large, tense bullae. Toxic epidermal necrolysis and Steven-Johnson syndrome are mucocutaneous druginduced or idiopathic skin reactions. Initial sore throat, fever, and headache may be present in both conditions. Skin patterns are characterized by skin tenderness and erythema of skin and mucosa, followed by extensive cutaneous and mucosal epidermal necrosis and sloughing. Diagnosis is based on the percent of epidermal skin detachment. Lichen planus appears as pruritic, polygonal, purple papules. Angioedema is a localized, rapid swelling of the face, hands, or genitalia. Case A 4-year-old boy presents with skin eruptions, fever, and diarrhea. Skin eruptions developed 1 week ago; they developed after exposure to multiple mosquito bites that left weepy, crusted areas. Over the past 2 days, the boy has become quiet, sleepy, and febrile; he has had a few loose stools. His past medical history is noncontributory, and his immunizations are up to date. On examination, you find a child in a mild distress; his temperature is 39 C. Heart rate is 100/min, and respirations are 22/min. On the skin of the arms and trunk, you notice multiple excoriations; there are a few fragile thin-roofed, flaccid, and transparent bullae, with a clear, yellow fluid that turns cloudy and dark yellow. Several bullae are ruptured, leaving behind rims of scales around erythematous moist bases, but no crusts. You also notice patches of skin of brown-lacquered appearance, with collarettes of scale and peripheral tubelike rims. Question For this condition, what is the primary mechanism of action of the antibiotic that represents the best treatment option?Correct answer: Inhibition of peptidoglycans synthesis Explanation The correction response is inhibition of peptidoglycans synthesis. Your patient most probably has bullous impetigo. The diagnosis of impetigo is usually made on the basis of the history and physical examination. Patients with softtissue infection accompanied by signs and symptoms of systemic toxicity should be given an antibiotic that covers against both Staphylococcus aureus and Streptococcus pyogenes. Empirical treatment is semisynthetic penicillin, or first- or second-generation oral cephalosporins; these inhibit cell wall synthesis by inhibiting the synthesis of peptidoglycans, thereby inhibiting the synthesis of the bacterial cell wall. Antibiotics that bind to ribosomes in order to inhibit protein synthesis (aminoglycosides, tetracyclines, chloramphenicol, erythromycin, clindamycin, oxazolidinones, telithromycin etc.) are rarely the drugs of choice for either a particular infection or for a particular bacterial species. They are generally not recommended for use in children. Rifampin is an example of a bactericidal antibiotic that inhibits RNA transcription by inhibiting RNA polymerase. It is active against Staphylococcus and Mycobacterium. Rifampin monotherapy is not recommended because of the high likelihood for the development of resistance; instead, rifampin is added to other antibiotics for the treatment of streptococcal or staphylococcal infections (usually in combination with vancomycin) or Haemophilus influenzaetype b infection. Antibiotics that disrupt cytoplasmic membrane are used as topical agents (e.g., bacitracin). DNA synthesis Inhibitors include fluoroquinolones and Metronidazole. The use of fluoroquinolones to treat infections in children in most countries is approved only under certain circumstances. Metronidazole could be useful foranaerobic and certain parasitic infections. Case A 35-year-old obese man presents with a 6-month history of itchy rash. He was referred to you by his primary care physician, who treated him for tinea cruris over a period of 4 months with limited success. A brief history reveals the patient is bipolar on lithium, does not smoke, and takes no other medications aside from the terbinafine (Lamisil) tablets prescribed by the primary physician. On physical examination, the rash is located primarily in the intertriginous areas of the groin, but it can also be seen in the axillary and sacral regions. The morphology is variable, but it is largely consistent with that of erythematous plaques. Scaling is widely observed, except for in the groin, where the plaques are moist and more confluent. The dermatologist does a KOH preparation of the scrapings and finds no hyphae. Question What is the most likely diagnosis?Correct answer: Psoriasis Explanation Psoriasis is a very common chronic inflammatory condition of the skin. The lesions are variably pruritic and are characterized by sharply demarcated papules and rounded plaques. A silvery scale is frequently observed covering the erythematous plaques. Depending on the distribution and character of the lesions, psoriasis can be further categorized into several sub-groupings. The most common subtype (plaque type) of psoriasis is usually distributed on the elbows, knees, sacral area/gluteal cleft, and scalp. However, there is also a less common variety known as inverse psoriasis. This is where the plaque lesions form in intertriginous regions in addition to scalp, palms, and soles. Because of the moisture in the intertriginous areas, scales may not be evident. Other forms of psoriasis include eruptive or guttate psoriasis as well as some variants where the lesions are more pustular in character. The etiology of psoriasis is not well defined, but there may be some association with certain medications, such as lithium and beta-blockers. Atopic dermatitis is the skin's reaction to allergy, be it food, asthma, or animal dander, etc. In children and adolescents, it is frequently localized to the flexural skin creases of the antecubital and popliteal fossae. Skin injury is more often a result of scratching than of the atopic process itself, and these individuals have a higher incidence of Staphylococcus aureus skin infections than do unaffected patients. Patients with atopic dermatitis are advised to avoid irritants and to keep skin moist (which includes avoiding hot showers and profuse scrubbing). Treatment often includes the judicious use of low-dose topical glucocorticoids and conservative administration of antihistamines to reduce the itching. Intertrigo is not an answer choice, but discussion here may be helpful. Stedman's Medical Dictionary (26th edition) defines intertrigo as: "irritant dermatitis occurring between folds or juxtaposed surfaces of the skin, as between the buttocks, between the scrotum and the thigh, beneath pendulous breasts, etc., caused by friction, sweat retention, moisture, warmth, and concomitant overgrowth of resident microorganisms, and occurring in young children and obese adults." Therefore, a patient with intertrigo could indeed have candidiasis, but a patient with candidiasis does not necessarily have intertrigo. Candidiasis occurs because of overgrowth of this group of yeasts in particular areas of the skin, those that are chronically wet, and especially in the intertriginous zones of the groin and beneath pendulous breasts. Patients with diabetes, chronic intertrigo, and cellular immune deficiency (as in HIV) are particularly susceptible. Obese patients have more intertriginous areas and are thus at risk. The rash is said to be macerated (i.e., displaying a waterlogged or soaked appearance characteristic of the dead surface skin). It is also described as erythematous, with marked inflammation, and it may be in a "satellite lesion" distribution. That is, smaller lesions a couple of cm out from the main larger one, which the "satellites" appear to orbit. The lesions may show scaling and skin scrapings will show pseudohyphae and yeast forms. Lichen planus is a condition that produces primary lesions described as pruritic, polygonal, flat-topped violaceous papules. Lesions may show thin grey lines (Wickham's striae), and they have a tendency to occur on wrists and shins, but can occur anywhere on the skin. Mucous membranes including the buccal mucosa can be involved. The etiology is not completely understood, and the course is variable, but the lesions usually disappear spontaneously within several months to 2 years. Treatment may include topical glucocorticoids. The rash of secondary syphilis can indeed manifest as moist pink lesions in the intertriginous regions. This occurs in about 10% of patients with secondary syphilis, and the lesions are called condylomata lata. However, secondary syphilis is not the best answer. While syphilis is notorious for masquerading as other diseases, there are certain clues to look for that are more typical of syphilis. The rash, which may be subtle, usually manifests as symmetric mucocutaneous lesions with some truncal distribution. Furthermore, nontender generalized lymphadenopathy is usually present and the primary chancre of syphilis will still be present in about 15% of patients with secondary syphilis. Finally, RPR should be positive in a patient with secondary syphilis. Other factors to consider are the patient's obesity, diabetes, complaints of vulval pruritus consistent with candidal vulvovaginitis, and positive HIV status. In summary, secondary syphilis would be an appropriate consideration in this patient, but it would not be the best answer in this case. Of parenthetical note, IV drug users have a high (upwards of 25%) false positive rate by reagin-type tests, such as RPR. Here is a list of each of the possible answer choices together with an oversimplified "lightning flash" association: Atopic dermatitis...allergic, flexural creases Candidiasis...diabetic, chronic intertrigo Lichen planus...pruritic polygons Psoriasis...silvery scaled papules and plaques Secondary syphilis...the masquerader Case A 4-year-old boy presents with a rash on his feet, ankles, wrists, and gluteal areas; the rash is accompanied by severe itching, particularly at night. His 6-month-old sister has a similar rash on her neck and head. On examination, you find pruritic erythematous papular and papulopustular skin changes between the web spaces of the fingers; changes are also seen on the flexor aspects of the wrists and in the genital and gluteal areas. On superficial epidermis, you find several short, elevated, red, tortuous lines; they have a small vesicle at the tip. Question What treatment you will suggest?Correct answer: Permethrin cream Explanation Both your patient and his sibling most probably have scabies: the pathognomonic sign is a short elevated pink or gray, straight or tortuous track in the superficial epidermis; there is also a small vesicle at the tip (burrow). Topical permethrin is the drug of choice. Low-strength hydrocortisone is used for the temporary relief of irritations, itching, and rashes caused by allergic reactions. The presence of similar symptoms in siblings should make you think about the infection or infestation; in such cases, the treatment should be causative. Clindamycin lotion is used as a topical antibiotic for acne. Selenium sulfide is sometimes used to treat tinea versicolor of the skin. Local tar soap is a traditional treatment of scabies; it has been replaced by permethrin, which is far more efficient. Case A 28-year-old woman has a history of obesity and diabetes. Upon physical exam, she has velvety hyperpigmented plaques over the back of her neck, groin, axilla, and breast area. The area has a dirty appearance with a rough texture. Question What treatment can be used to help treat this condition?Correct answer: Metformin Explanation Metformin is the correct answer because, while there is no specific treatment for acanthosis nigricans, this skin condition is usually a sign of hyperinsulinemia and insulin resistance, which can be treated by weight loss and the use of metformin. Antibiotics treat bacterial infections, and acanthosis nigricans is not a bacteria. Topical steroids commonly treat eczema and dermatitis through anti-inflammatory properties that will not help acanthosis nigricans. Acanthosis nigricans is not a fungus. Antifungals help kill the fungal cells by allowing the fungal cells to leak out and the cell to die. Acanthosis nigricans would not improve with anticoagulants. An anticoagulant helps prolong clotting time and prevent blood coagulation. Case A 77-year-old man presents with a rash. The patient states that the rash began a few months ago as several small reddish-brown spots on his shoulders. Over time, the spots became bigger, with some of them growing together to form large well-defined patches. The surrounding skin is not affected. He denies any fever, and he states that he has never had this before. His past medical history is significant for hypertension and obesity. He is otherwise healthy, and he denies any other symptoms. On physical exam, he is a well-developed obese man in no acute distress. He has large areas of well-defined patches that have various shades of brown. Examination of skin scrapings under a microscope shows hyphae. Question This condition is usually caused by what organism?Correct answer: Malassezia Explanation Tinea versicolor is a fungal infection common in adults and adolescents. The most commonly affected areas include the chest, back, and shoulders. Occasionally, it can be found on the face. It causes the affected skin to change color and become either lighter or darker. It was believed to be caused by a yeast called Malassezia furfur, but recent evidence points at Malassezia globosa as the cause. Tinea versicolor is not contagious and is very common. It can recur, so treatment may need to be repeated. The affected skin becomes reddish-brown to brown or may be light in color. Initially, the lesions are well-defined round-to-oval scaly macules. Over time, they tend to coalesce and form patches with various amounts of shading. The colors can be darker or lighter than the unaffected skin. Darker patches may disappear shortly after treatment is started, but lighter patches may take longer to go away. The skin discoloration is not permanent, and the color will eventually return to normal. Diagnosis can be confirmed by using an ultraviolet light (Wood light). The affected areas usually fluoresce and appear to be orange in color. If they do not fluoresce, the skin will appear darker than normal skin. A scraping of the skin will show the presence of hyphae in a characteristic "spaghetti and meatballs" appearance when exposed to potassium hydroxide. Diagnosis can also be confirmed by microscopic analysis. A scraping of the area placed in potassium hydroxide solution will show hyphae if a fungal infection is present. Tinea versicolor can be treated with several preparations that are applied to the skin. Over-the-counter preparations usually contain miconazole, ketoconazole, or clotrimazole; they can be found in shampoo or cream form. There are also prescription strength versions of these preparations. Oral medications (e.g., itraconazole or ketoconazole) also exist. Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus do not show hyphae under the microscope. Trichophyton rubrum is a common fungus that causes ringworm, athlete's foot, and jock itch. Case A 21-year-old man presents with itchy skin changes. He works as a lifeguard. About a week ago, he noticed red, round patch on his belly that spread to his trunk and legs. He denies recent infections, allergies, and illnesses; he does not take any medications, and he admits that he occasionally smokes marijuana. The rest of his personal and family history is noncontributing. On examination, you find round and annular, scaly, pruritic, papulosquamous changes on his torso and legs. There are no changes on his mucosa, and the rest of physical examination is within normal limits. Question In order to make a diagnosis, what should be your next step?Correct answer: Potassium hydroxide preparation Explanation The clinical picture of skin changes and the patient's occupational history suggest tinea corporis. You should confirm your diagnosis with potassium hydroxide preparation of skin scrapings that will demonstrate the presence of fungal hyphae. If the potassium hydroxide test is negative, then you should consider a skin biopsy to identify the pathohistological patterns of the other dermatoses. The Venereal Disease Research Laboratory test (VDRL) is a non-treponemal screening test for syphilis. Secondary syphilis often appears as symmetric pink, reddish, or brown papules on the trunk and proximal extremities, including the palms and soles. However, they are non-itchy, and mucosal structures and other parts of the body are also involved. Secondary syphilis occurs 2 to 10 weeks after the primary chancre. Prick test with intradermal injections are done to assess allergies to drugs or bee venom. Your patient has no such a history. Tzanck smear is sometimes used to the diagnosis of chickenpox (highly contagious viral disease caused by varicella zoster). Diagnosis is usually clinical, but there is no reason to think about chickenpox in this patient. Chickenpox usually starts 10 - 21 days after a contact with infected person; it begins as an itchy vesicular rash on the body and head. Typically, you will find crops and lesions at various stages of healing. Case A 7-year-old girl was playing at a local playground near her home. She was playing kickball and the ball went into the bushes and she retrieved it. After several minutes, she noticed a red lesion on her right forearm. She rushed home and told her mom. The mother looked at the lesion and noticed a small red area and sprayed the area with a local antiseptic that she had in her medicine cabin. The child only complained that it burned. A few hours later, the mother looked at the area and noticed that a white area appeared. She thought nothing of it and placed a band-aid over the bite. Before the child went to bed that night, she removed the band-aid and notice that the area had darkened. She then took the child to the ER for further evaluation...