Medical Mycology Flashcards
1- A soldier from Sudan experienced a penetrating wound of his foot 10 years ago which progresses slowly, leading to draining sinuses, scarring, swelling, and deformity of his lower extremity. He presents to your office and you collect samples for KOH, histology and culture. He relapses after a debridement and a trial of oral antifungal therapy. Which of the following is NOT true of this condition?
A. Caused by true fungi
B. Caused by filamentous bacteria
C. Characterized by triad of tumefaction, draining sinuses, grains or granules
D. Bony involvement may occur
E. Cutaneous disease results from hematogenous dissemination of the responsible pathogen
Correct choice: E. Cutaneous disease results from hematogenous dissemination of the responsible pathogen
Explanation: Mycetoma (maduromycosis, Madura foot, fungus tumor) is caused by true fungi (eumycotic) or filamentous bacteria (actinomycotic). Disease progresses slowly. It is characterized by the triad of tumefaction, draining sinuses, grains or granules (aggregates of organism) causing scarring, swelling, deformity. Bony involvement may occur. For evaluation, collect grains for KOH, histology and culture.
- A- patient with a CD4 count of 48 presents with several dozen umbilicated papulonodules and complains of fatigue and fever. Which of the following is the least likely underlying infectious process?
A. Histoplasmosis
B. Coccidioidomycosis
C. Paracoccidioidomycosis
D. Penicilliosis
E. Cryptococcosis
Correct choice: C. Paracoccidioidomycosis
Explanation: C is the correct answer. The remaining choices are in the differential diagnosis of molluscum- l ike lesions, especially in AIDS or immunocompromised patients. Paracoccidioidomycosis does not present with molluscum-type lesions.
3- What is the causative organism?
A. Fonsecaea pedrosoi
B. Actinomadura pelletieri
C. Lacazia loboi
D. Prototheca wickerhamii
E. Rhinosporidium seeberi
Correct choice: A. Fonsecaea pedrosoi
Explanation: Here you can see the classic copper pennies of chromoblastomycosis. Fonsecaea pedrosi causes chromoblastomycosis. Actinomycotic red granules are due to actinomadura pelletieri. Lacazia loboi causes lobomycosis, prototheca wickerhamii causes protothecosis and rhinosporidum seeberi causes rhinosporidiosis.
4- A patient has a positive Wood’s lamp exam that is caused by pteridine. What is the causative organism?
A. Microsporum ferrugineum
B. Corynebacterium minutissimum
C. Trichophyton violaceum
D. Pseudomonas aeruginosa
E. Trichophyton tonsurans
Correct choice: A. Microsporum ferrugineum
Explanation: Wood’s light positive dermatophytes (M. canis, M. audouinii, M. distortum, M. ferrugineum, T. schoenleinii, and sometimes M. gypseum) fluoresce secondary to pteridine. Corynebacterium can fluoresce as well due to production of coproporphyrin III. Pseudomonas fluoresces from production of pyocyanin. The other organisms do not react with a Wood’s light.
5- A liver transplant patient on prednisone, tacrolimus and mycophenolate mofetil developed an enlarging necrotic ulceration of the face. Bedside gram stain of purulent contents was obtained and supports the diagnosis of which infectious organism?
A. Chromoblastomycoses
B. Cryptococcus
C. Mucor spp.
D. Blastomyces dermatitidis
E. Trichophyton mentagrophyes
Correct choice: C. Mucor spp.
Explanation: Large ribbon-like hyphae with 90-degree branching is consistent with Zygomycosis (Mucormycosis). The most common species include Mucor spp, Rhizopus spp and Absidia spp. Risk factors for mucormycosis include immunosuppression (neutropenia), diabetes and severe burns.
6- What is the best test to confirm the most likely diagnosis?
A. DsDNA antibody
B. Anti-Ro antibody
C. Biopsy
D. KOH
E. Gram stain
Correct choice: D. KOH
Explanation: The picture depicts tinea faceii. A KOH exam should be performed to look for hyphae. The other options can present with erythema on the face, but the scaling and higher concentration of papules at the periphery suggest a fungal origin. Tinea faceii is also more common.
7- A patient presents to your clinic after returning from vacation with painless smooth-surfaced nodules on the arm. Biopsy of one of the nodules reveals round, brownish cells attached to one another with narrow connections. What is the most likely diagnosis?
A. North American Blastomycosis
B. South American Blastomycosis
C. Chromoblastomycosis
D. Keloidal Blastomycosis
E. Coccidiomycosis
Correct choice: D. Keloidal Blastomycosis
Explanation: The question stem describes the typical clinico-pathologic findings of keloidal blastomycosis (Lobomycosis), which is caused by Lacazia loboi. This deep fungal organism is
found in the Amazon basin and Gulf of Mexico, and is associated with dolphins. The biopsy findings are also described as “brass knuckles” or a “chain of coins.” The treatment of choice is surgical excision as antifungals are ineffective. The remaining answer choices do not present with the clinico-pathologic findings described in the
stem.
8- A Caribbean agricultural worker sustained a prior traumatic injury to her leg decades ago. She now has cauliflower-like tumors that coalesce into irregular verrucous plaques. A biopsy shows brown, round, thick walled cells 5-12 microns thick with septations. What is the causative organism causing this patient’s condition?
A. Sporothrix schenckii
B. Pseudallescheria boydii
C. Lacazia loboi
D. Blastomyces dermatitidis
E. Fonsecaea pedrosoi
Correct choice: E. Fonsecaea pedrosoi
Explanation: Chromoblastomycosis (chromomycosis, verrucous dermatitis) is seen mainly in the tropics and subtropics especially the Caribbean islands. It is caused by saprophytic organisms found in soil, decaying vegetation and wood and the most common causative organism is Fonsecaea pedrosoi. It is usually instigated by a traumatic injury in agricultural workers to the foot, leg, occasionally chest and shoulders. It is characterized by cauliflower-like tumors which may coalesce, irregular verrucous plaques, nodules, annular plaques with a central clearing and transepidermal elimination. A biopsy shows pseudoepitheliomatous hyperplasia, epidermal microabscesses, and a granulomatous tissue response. “Copper pennies” (sclerotic bodies, medlar bodies, chromobodies) are brown, round, thick walled cells 5-12 microns with septations characteristic for this condition on histology. Lacazia loboi causes lobomycosis and Blastomyces dermatitidis causes blastomycosis. Sporothrix schenckii causes sporotrichosis. Pseudallescheria boydii causes a mycetoma.
9- You assess a patient in clinic with thick nails with debris that begins distally and involves the nail bed, nail plate, and lateral nailfold. A nail culture will most likely grow which organism?
A. T. megnininii
B. T. schoenleinii
C. T. tonsurans
D. T. mentagrophytes
E. T. rubrum
Correct choice: E. T. rubrum
Explanation: Distal lateral subungual onychomycosis is a fungal nail infection that begins distally and involves the nail bed, nail plate and lateral nail fold. It appears as a thick nail with debris, loose or cracked nail plate. The most likely causative organism is T. rubrum.
10- The most likely organism to cause this infection is:
A. T. tonsuran
B. C. immitis
C. C. albicans
D. P. aeruginoas
E. T. verrucosum
Correct choice: C. C. albicans
Explanation: The organism that causes erosio interdigitalis blastomycetica is candida albicans.
While other options may be causes of cutaneous infection, interdigital involvement is seen most often with candidal infection.
11- This patient had been treating a scaly rash with clobetasol for 4 weeks. It has significantly increased in size despite treatment and is very itchy. Which of the following treatments is most appropriate?
A. Oral prednisone
B. Oral terbinafine
C. Topical fluocinonide
D. Topical econazole
E. Topical pimecrolimus
Correct choice: B. Oral terbinafine
Explanation: The correct answer is B. The picture and history are suggestive of a fungal process; it likely started out as tinea corporis and, with topical application of clobetasol, progressed to the diagnosis shown- Majocchi’s granuloma. This often requires oral (not topical) antifungal treatment. Terbinafine is typically first line.
12- Which of the following is NOT caused by a dematiaceous fungus?
A. Chromoblastomycosis
B. Tinea nigra
C. Black piedra
D. Eumycotic mycetoma
E. Hyalohyphomycosis
Correct choice: E. Hyalohyphomycosis
Explanation: The correct answer is E. Hyalohyphomycosis may be caused by Penicillium marneffei, Paecilomyces, and Fusarium. Tinea nigra and black piedra are types of phaeohyphomycoses (pigmented hyphae) and chromoblastomycosis has pigmented yeast.
13- What is the most common cause, in the United States, of the disease seen in this kodachrome?
A. Trichophyton tonsurans
B. Trichophyton rubrum
C. Candida
D. Staph aureus
E. Trichophyton mentagrophytes
Correct choice: B. Trichophyton rubrum
Explanation: T. rubrum is the most common cause of onychomycosis in the USA. Trichophyton mentagrophytes is the most frequent cause of White Superficial Onychomycosis. T. tonsurans is the most common cause of tinea capitis in the US. Candida can cause chronic paronychia. Staph aureus is the most common cause of acute paronychia.
14- What is the best treatment for this infection?
A. Fluconazole
B. Ciprofloxacin
C. Argatroban
D. Itraconazole
E. Penicillin
Correct choice: D. Itraconazole
Explanation: The image shown is blastomycosis, indicated by the broad-based buds and the refractile wall. This is a GMS stain which highlights the walls of the blastomycosis. This is treated with itraconazole, or amphotericin B if the infection is severe.
15- Which two characteristics combined form a significant risk for acquiring sporotrichosis? 1. Animal handler 2. Male gender 3. Alcoholism 4. Filipino or African decent 5. Genetic predisposition
A. 1, 2
B. 1, 3
C. 2, 5
D. 4, 5
E. 3, 4
►B
A variety of domestic animals can carry Sporotrichosis. Alcoholism increases the risk for this cutaneous infection.
-What is the most frequently reported cause of primary cutaneous aspergillosis?
A. Aspergillus flavus
B. Aspergillus fumigatus
C. Aspergillus niger
D. Aspergillus solani
E. Aspergillus marneffei
►A
Primary cutaneous aspergillosis is a rare disease reported mostly frequently in children with hematologic malignancies who developed skin lesions at the site of IV canulas.
17- Which of the following DOES NOT typically cause white superficial onychomycosis?
A. Aspergillus species
B. Fusarium species
C. Trichophyton mentagrophytes
D. Scopulariopsis species
E. Trichophyton rubrum
►E
In white superficial onychomycosis, the organism only invades the superficial nail plate, and it clinically appears as chalky white patches on the nails. The most common organism is T. mentagrophytes, but Aspergillus, Cephalosporium, Fusarium, Acreconium and Scopulariopsis are implicated as well.
18- A blood culture from a neutropenic patient with onychomycosis grew which of the following organism:
A. Scopulariopsis sp
B. Aspergillus sp
C. Fusarium sp
D. Acremonium sp
E. T. rubrum
►C
Fusarium is one of the few moulds, which yield positive blood cultures, neutropenia is one of the risk factors for Fusariosis.
19- Although this organism is not a fungus, it stains with PAS and GMS and produces 8-20 micron spherules in tissue. This organism can be identified as:
A. Rhinosporidium seeberi
B. Coccidioides immitis
C. Penicillium marneffei
D. Prototheca wickerhami
E. Leishmania mexicana
►D
This achloic algae produces spherules or sporangia 8-20um in tissue. The mature form is called a morula. Rhinosporidium is also not a fungus however, it produces sporangium 250-350 microns.
20- Which of the following is a fluorescent ectothrix dermatophyte?
A. Trichophyton rubrum
B. Trichophyton mentagrophytes
C. Microsporum ferrugineum
D. Trichophyton violaceum
E. Microsporum nanum
►C
Fluorescent ectothrix dermatophytes include M. canis, M. audouinii, M. distortum, M. ferrugineum, and sometimes M. gypseum and T. schoenleinii (“Cats And Dogs Fight and Growl Sometimes.”) Nonfluorescent ectothrix dermatophytes include T. mentagrophytes, T. rubrum, T. verrucosum, T. megninii, and M. nanum. Endothrix dermatophytes include T. rubrum, T. gourvilli, T. yaounde, T. tonsurans, T. schoenleinii, T. soudanense, and T. violaceum.
21- Which of the following statements regarding candidal infection is FALSE?
A. Candida species displays true hyphae on potassium hydroxide examination
B. Predisposing factors for candidal infection include diabetes mellitus, hyperhidrosis and broad spectrum antibiotics
C. Candida albicans is the number one cause of mucocutaneous infections
D. Candidal infections typically do not spare the scrotum
E. Candida species may be associated with granuloma gluteale infantum
►A
Candida species are part of the resident flora but they are also the most common cause of opportunistic mycotic infection. Cutaneous clinical manifestations include thrush, perleche, paronychia, onychomycosis, intertrigo, and folliculitis. Candida albicans is the most common organism; however, C. dubliniensis is often implicated in mucosal disease in AIDS patients. C. parapsilosis causes chronic paronychia and C. glabrata is fluconazole resistant. Infection is most common in the extreme of age, and the mucosal disease is prevalent in HIV patients. Factors predisposing patients to infection include impaired mucocutaneous barrier function, immunodeficiencies, broad spectrum antibiotic use, malignancies, heat, humidity, friction, diabetes, and indwelling catheters. Groin infections often involve the scrotum unlike tinea cruris caused by dermatophytes. On KOH examination, budding yeast and pseudohyphae (not true hyphae) are diagnostic. Predisposing factors for granuloma gluteale infantum include occlusion, topical corticosteroids, and possibly Candida diaper dermatitis.
22- Erythematous to violaceous papules that may progress to nodular and necrotizing skin lesions in neutropenic patients may be caused by which of the following organisms?
A. Trichosporon asahii
B. Trichosporon beigelii
C. Trichosporon ovoides
D. Trichosporon inkin
E. Trichophyton rubrum
►A
Trichosporon asahii can cause trichosporanosis, which presents with disseminated disease in neutropenic patients. Patients may present with erythematous to violaceous papules that may progress to nodular and necrotizing skin lesions. Trichosporon beigelii (new nomenclature: Trichosporon ovoides and Trichosporon inkin) causes white piedra and other superficial infections.
23- A biopsy shows broad-based budding thick walled yeast cells, 10-15 um with a double contoured appearance.
A. This yeast has a yeast phase at room temperature
B. Does not grow at 37º C
C. Usually produces a severe characteristic pulmonary disease
D. May be found in dogs
E. Is transmitted by mosquitoes
►D
This biopsy describes Blastomyces dermatitidis which generally can be found in decaying vegetation but can be carried by dogs.
24- Which of the following is true regarding Dermatophyte Test Media (DTM)?
A. DTM contains chlortetracycline and minocycline
B. Alizarin red is the indicator present in DTM
C. Non-dermatophytes cause the media to turn yellow due to acid byproducts
D. DTM is useful for culturing dermatophytes from skin and nails, but not hair.
E. Dermatophytes utilize glucose as a carbon source, producing alkaline byproducts.
►C
Dermatophyte Test Media (DTM) contains peptones, dextrose, gentamicin, chlortetracycline, cycloheximide, and phenol red. Dermatophytes utilize protein as a carbon source producing alkaline byproducts causing the media to turn from amber to red. Nondermatophytes cause the media to turn yellow due to acid byproducts.
25- The most common eumycotic organism in the US produces which color grains in its microcolony?
A. White
B. Black
C. Red
D. Yellow
E. Green
►A
The most common cause of fungal (eumycotic) eumycetoma in the US is Pseudallescheria boydii. This and Acremonium produce white colonies. Black colonies are caused by Exophilia, Madurella, and Curvalaria. Red colonies are created by Actinomadura pelletieri. Yellow colonies are made by Streptomyces and Nocardia, both causes of bacterial mycetoma.
26- All of the following statements about paracoccidioidomycosis are true EXCEPT?
A. It is most common in male agricultural workers
B. It has a characteristic ―mariner‘s wheelǁ appearance on histopathology
C. Disease is almost always confined to the skin
D. It is endemic to Brazil
E. It may cause mucocutaneous lesions
►C
Paracoccidioidomycosis is caused by Paracoccidioidomycosis brasiliensis, and is endemic to Central and South America, especially Brazil, Argentina, Venezuela, Ecuador and Colombia. Male agricultural workers are at greatest risk. Infection is most commonly caused by direct inoculation which leads to pulmonary disease. Lung disease may be followed by dissemination to mucocutaneous surfaces, gastrointestinal tract, spleen, adrenal glands, and lymph nodes. Cutaneous lesions are verrucous and/or ulcerative, and usually found on the face and in the nasal and oral mucosa. Primary mucocutaneous disease exists as well and is caused by direct inoculation. Biopsy specimens display multiple narrow-based budding yeast cells, described as a ―mariner‘s wheel.ǁ The treatment of choice is itraconazole.
27- An elderly lady with moccasin-type tinea pedis has a fungal culture which demonstrates smooth, teardrop-shaped microconidia which produce a ―port-wineǁ pigment. The organism is:
A. Trichophyton verrucosum
B. Microsporum canus
C. Trichophyton rubrum
D. Microsporum gypseum
E. Trichophyton mentagrophytes
►C
Trichophyton rubrum is an anthropophilic dermatophyte that is a cause of T. pedis, T. manum, T. corporis, T. cruris, onychomycosis, Majocchiǁs granuloma, and rarely T. capitis. Colonies appear
as fluffy to granular white to cream colored with reverse non-diffusible port-wine or red pigment. Macroconidia are rare, thin-walled pencil shaped. Microconidia are delicate teardrop shaped.
28- A pet store owner comes into your office with pruritic scaly plaques on his arms. A fungal culture demonstrates a yellow colony with spindle-shaped macroconidia which grows on polished rice grains. The organism is:
A. Microsporum canis
B. Epidermophyton floccosum
C. Trichophyton rubrum
D. Microsporum gypseum
E. Trichophyton tonsurans
►A
Microsporum canis os a zoophilic dermatophyte, which causes ectothrix invasion when infecting the hair. Colonies of M. canis are flat, spreading, white to cream-colored with a dense cottony surface, The reverse of the plate is a canary yellow. Wet mount of the fungus shows spindleshaped macroconidia with 5-15 cells and often have a terminal knob.
29- The most reliable method for distinguishing between Trichophyton rubrum and T. mentagrophytes is:
A. Morphology of microconidia
B. Morphology of macroconidia
C. Pigmentation studies
D. Hair perforation test
E. Colony morphology
►D
The diagnostic morphology of the Trichophytons overlap and may be difficult to differentiate. T. mentagrophytes produces a positive hair perforation test (wedges in the test hair).
30- If the diagnosis is phaeohyphomycosis, what is the organism 1. Alternaria sp. 2. Bipolaris sp.
3. Fusarium sp. 4. Exophiala sp.
A. 1,2,3
B. 2,3,4
C. 1,2,4
D. 1,3,4
E. All of these answers are correct
►C
All these organisms are dematiaceous, Fusarium is a hyalohyphomycete.
31- Which of the following is TRUE regarding coccidiomycosis?
A. First line treatment in pregnancy is itraconazole
B. Droplet transmission is the most common method of acquisition of disease
C. Southeast Asians are at a higher risk of disseminated disease
D. Erythema nodosum is associated with a poor prognosis
E. Approximately 75% of those contracting the disease will be symptomatic
►C
Southeast Asians and African Americans are at a higher risk for disseminated cocci, as are pregnant women and the immunocompromised. Approximately 60% of those contracting coccidiomycosis
are asymptomatic, and the disease is infectious not contagious. The most common method of disease acquisition is inhalation from the soil during natural events (dust storms etc). Erythema nodosum is associated with a good prognosis and the first-line treatment during pregnancy is amphotericin B. (JAAD 2006 CME)
32- A fungal culture demonstrates a suedelike cream-colored colony of teardrop and balloon-shaped microconidia which produce a red-brown pigment. Which of the following is true of this organism?
A. Causes ectothrix infection
B. Requires partial thiamine for growth
C. Does not have arthroconidia
D. Causes fluorescent hair infection
E. Is not a cause of tinea unguim
►B
Trichophyton tonsurans is an anthropophilic dermatophyte that causes non-fluorescent endothrix hair invasion. It can cause black dot tinea capitis, tinea corporis, tinea pedis, and tinea unguium. An important identifying feature of T. tonsurans is its red-brown pigment that diffuses into the medium. Also, abundant tear-drop or club shaped microconidia can be found. It grows best in the presence of thiamine.
33- This organism is often considered a contaminant but has been reported to cause onychomycosis:
A. Sepedonium
B. Curvularia
C. Scopulariopsis
D. Penicillium
E. Phialophora
►C
Causes white superficial onychomycosis.
34- Which of the following statements regarding histoplasmosis is TRUE?
A. Terbinafine is the treatment of choice
B. Histoplasma capsulatum is a yeast at 25°C
C. The organisms are intracellular on histological examination
D. The disease is most common in the San Joaquin Valley
E. The disease is primarily a mucocutaneous infection
►C
Histoplasmosis is primarily a pulmonary infection that can disseminate to other organs. It is endemic to the Ohio, Missouri and Mississippi River Valleys where the bird and bat droppings in the soil contain the fungus. Primary cutaneous disease is extremely rare. At 25°C it displays septate hyphae and at 37°C H. capsulatum is a yeast. Itraconazole is the treatment of choice. On histopathological examination, intracellular organisms that display a halo are seen. The halo is not the result of a capsule but rather shrinkage artifact.
35- All of the following are common causes of chromoblastomycosis EXCEPT:
A. Cladosporium carrionii
B. Rhinocladiella aquaspera
C. Phialophora verrucosa
D. Pseudallescheria boydii
E. Fonsecaea pedrosi
►D
Chromoblastomycosis is a chronic fungal infection of the skin and the subcutaneous tissue caused by traumatic inoculation of a specific group of dematiaceous (pigmented) fungi. Fonsecaea pedrosoi is the most common causative organism, but Fonecaea compacta, Rhinocladiella aquaspersa, Phialophora verrucosa, Exophilia jeanselmei and Cladosporium carrionii are pathogenic as well. It is found most commonly in agricultural workers in the tropics and subtropics, and it is notoriously resistant to therapy. It presents as verrucous papules and plaques that may coalesce. Histopathological findings include brown, thick-walled cells known described as ―copper pennies.ǁ Early in its course, limited disease may respond to surgical excision, electrodessication or
cryosurgery. More extensive lesions may require systemic antifungal agents including itraconazole or terbinafine, which are the treatments of choice.
36- A 37 year old woman from New Mexico, now 30 weeks pregnant, presents with flu-like symptoms. Chest x-ray revealed diffuse miliary infiltrates, with blood cultures growing Coccidioidis immitis. What is the treatment of choice?
A. Amphotericin B
B. Terbinafine
C. Itraconazole
D. Griseofulvin
E. No therapy
►A
There is an increased risk of dissemination of Coccidiomycosis in pregnant women, especially during the third trimester and the post-partum period. In a review by Crum et al, maternal demise correlated with disease diagnosed later in pregnancy, with only 45% of patients diagnosed in the third trimester surviving (Am J Medicine 2006;119(11):Pages 993.e11-993.e17). Given that azoles have been shown to cause teratogenicity, amphotericin B is recommended as the therapy in pregnant women.
37- Which of the following organisms causes favus?
A. Trichophyton schoenleinii
B. Trichophyton mentagrophytes
C. Microsporum canis
D. Trichophyton rubrum
E. Microsporum distortum
►A
Favus is a chronic dermatophyte infection defined by the presence of yellowish crusts in the hair follicles called scutula. Prolonged infections lead to cicatricial alopecias of the scalp and glabrous skin. The infection is most commonly caused by Trichophyton schoenleinii.
38 -Which of the following causes “black dot ringworm”?
A. M. canis
B. T. violaceum
C. T. verrucosum
D. M. gypseum
E. M. auddouinii
►B
“Black dot ringworm” is endothrix tinea capitis. Black dots are remnants of brittle hair broken at the surface of the scalp (cuticle intact). On KOH prep, spores are seen within the hair shaft. Causes are
T. rubrum, T. gourvilli, T. yaounde, T. tonsurans, T. schoeleinii, T. soudanense, and T. violaceum (“Ringo Gave Yoko Two Squeaky Violins.”). T. verrucosum causes nonfluorescent ectothrix tinea capitis. M canis, gypseum, and auddouinii also cause ectothrix tinea capitis.
39- Which one of the following is not caused by a Candida infection?
A. Angular cheilitis
B. Balanitis
C. Median rhomboid glossitis
D. Leukoplakia
E. Mycetoma
►E
Candidal infections may clinically present as thrush/leukoplakia, perleche/angular cheilitis, vulvovaginitis, balanitis, paronychia, onychomcosis, intertrigo, and folliculititis. Median rhomboid glossitis is now also associated with candidal infections. Mycetomas are caused by true fungi (eumycetoma) or filamentous bacteria (actinmycetoma).
40- A patient with a pulmonary infection and cervical adenopathy has vesicles, papules and ulcerations on the oral and nasal mucosa. Tissue culture reveals yeast with multiple buds giving a marinerǁs wheelǁ appearance. The organism is:
A. Penicillium marneffei
B. Coccidioides immitis
C. Paracoccidioides brasiliensis
D. Blastomyces dermatitidis
E. Leishmania mexicana
►C
Paracoccidioides brasiliensis causes a chronic progressive infection that is most commonly seen in rural areas of South America. Patients may have constitutional symptoms, lung involvement, ulcers of the upper respiratory and digestive tract, and verrucous/ulcerated cutaneous lesions. Classically, Paracoccidioides brasiliensis has a marinerǁs wheelǁ appearance.
41- This 16 year-old patient was recently diagnosed with HIV, the diagnosis is:
A. Distal Onychomycosis
B. Proximal Subungual Onychomycosis
C. Proximal White Subungual Onychomycosis
D. White Superficial Onychomycosis
E. Paronychia with Candida Onychomycosis
►C
Proximal White Subungual onychomycosis is an AIDS marker, nails have a characteristic white opaque appearance beginning in the region of the lunula and extending distally under the nail plate.
42- The etiologic agent responsible for White Piedra is:
A. Candida albicans
B. Pityrosporum obiculare
C. Corynebacterium tenuis
D. Piedra hortai
E. Trichosporon ovoides
►E
Formerly known as T. beigelii.
43- Which of the following statments regarding pseudohyphae is incorrect?
A. Pseudohyphae are seen in yeasts
B. Are constricted at septations
C. Branching occurs at septations
D. The terminal cell is smaller than the others
E. Are not septated
►E
Pseudohyphae are seen in yeast and resemble true hyphae except that they are constricted at septations, branching occurs at septations, and the terminal cell is smaller than the others. They are septated.
44 -Culturing T. rubrum from a white opacity on the fingernail plate should prompt testing for what?
A. Diabetes mellitus
B. Hypothyroidism
C. Hyperthyroidism
D. HIV
E. Cirrhosis
►D
White superficial onychomycosis of the fingernails is a marker for immunosuppresion and should prompt testing for HIV. Generally, T. mentag is the most common cause of white superfical onychomycosis. However, in immunosuppressed patients, T. rubrum is the more common dermatophyte.
45- A creamy white colony might be any of these organisms except:
A. Candida albicans
B. Prototheca wickerhamii
C. Curvularia
D. Sporothrix schenckii at 37º C
E. Cryptococcus neoformans
►C
Is a dematiaceous organism and is the only organism listed that does not produce creamy white colonies.
46- White piedra is caused by:
A. Trichophyton cutaneum
B. Trichophyton inkin
C. Trichophyton asahii
D. Trichophyton ovoides
E. Trichophyton mucoides
►A
Patients with white piedra are infected with Trichophyton cutaneum also known as Trichophyton beigelii. The treatment should be oral azole antifungals and shampoos without shaving the scalp.
47 -This organism does not produce microconidia. The macroconidia are club shaped, and smooth walled, they grow singly or in clusters.
A. Trichophyton rubrum
B. Epidermophyton floccosum
C. Microsporum gypseum
D. Microsporum canis
E. Trichophyton mentagrophytes
►B
This is the only organism in this list that fits this description.
48- Septate true hyphae are characterized by:
A. Transverse cross walls forming within the hyphae
B. Discrete unicellular bodies
C. Constrictions at septations
D. Branching occuring at septations
E. A terminal cell that is smaller than the others
►A
Hyphae are vegetative tube-like structures. In septate hyphae, transverse cross walls form within the hyphae. Pseudohyphae, seen in yeast, resemble true hyphae except that they are constricted at septations, branching occurs at septations, and the terminal cell is smaller than the others.
49- Which of the following is most likely to be a primary cutaneous infection?
A. North American Blastomycosis
B. Histoplasmosis
C. Paracoccidioidomycosis
D. Cryptococcosis
E. None
►A
All other mycoses are primary pulmonary infections, which may disseminate to the skin.
50- A 45 year-old agricultural worker from Brazil presented with ulcers of the buccal mucosa and tongue. Cervical lymph nodes were tender and enlarged. The biopsy would most likely reveal:
A. Yeast cells in chains and a large thick walled round central yeast cell surrounded by several thinly attached budding smaller yeast cells
B. Yeast cells with large capsules
C. Small budding yeast cells
D. Yeast cells with pseudohyphae
E. Copper pennies
►A
Yeast cells in chains and a large thick walled round central yeast cell surrounded by several thinly attached budding smaller yeast cells p.18. This biopsy is describing Paracoccidioides brasiliensis, an organism endemic in Brazil. Its yeast form seen in tissue produces a Mariners wheel-like configuration. Generally this organism is inhaled and disseminates causing mucocutaneous lesions with lymphadenopathy.
51- A patient with white nodules on the hair shaft has a KOH which shows hyphae and arthroconidia. The etiology is:
A. Corynebacterium minutissimum
B. Exophiala wernickii
C. Piedraia hortae
D. Trichosporon beigelii
E. Corynebacterium tenuis
►D
White piedra is an infection of the hair shaft caused by Trichosporon beigelii. Unlike black piedra which is firmly adherent to the shaft, white piedra presents as light brown nodules composed of hyphae and arthroconidia, which move easily along the hair shaft. The most common sites of infection occur on the mustache, beard and pubic area.
52 -The most sensitive microscopic test for fungal infection is:
A. Potassium Hydroxide
B. Potassium Hydroxide with DMSO
C. Chlorazol Black E
D. Calcofluor white
E. Swartz Lamkins stain
►D
Calcofluor white is the most sensitive microscopic test for fungal infection. It is a glucan specific immunofluorescent stain. The remaining options are useful in direct microscopic examination, but not the most sensitive.
53 -A patient with scaly feet has a positive KOH. Fungal culture reveals smooth, club-shaped macroconidia attached to hyphae in groups. No microconidida are seen. The organism is:
A. Microsporum canis
B. Epidermophyton floccosum
C. Trichophyton rubrum
D. Microsporum gypseum
E. Trichophyton tonsurans
►B
The wet mount Epidermophyton floccosum shows smooth, thin-walled macroconidia without microconidia. The appearance is occasionally referred to as ―snow shoesǁ. Epidermophyton floccosum is incapable of hair invasion, and therefore, does not cause tinea capitis.
54- A whitish, heaped and convoluted colony with growth submerged into the agar and a colorless reverse was isolated from the scalp of a 35-year-old male. The organism did not produce any conidia. The diagnosis most likely is:
A. Microsporum canis
B. Microsporum ferrugineum
C. Trichophyton rubrum
D. Trichophyton tonsurans
E. Trichophyton schoenleinii
►E
Produces a white cerebriform colony lacking any conidia. M. ferrugineum produces a rust colored colony with bamboo-like hyphae without conidia. The other organisms produce micro and macroconidia.
55- A horticulturist of sphagnum moss topiaries comes in with a nodular eruption with lymphangitic spread and treatment with oral potassium iodide is initiated. What is the most well recognized side effect of this treatment.
A. Gastrointestinal distress
B. Shortness of breath
C. Flushing
D. Angioedema
E. Pruritus
►A
This patient has sporotrichosis. Sporotrichosis is mainly an occupational disease of farmers, gardeners, and horticulturists. Persons who handle thorny plants, sphagnum moss, or baled hay are at increased risk. Outbreaks have occurred in nursery workers who handled sphagnum moss, rose gardeners, children playing on baled hay, and greenhouse workers who handled bayberry thorns contaminated by the fungus. Classic treatment is with oral potassium iodide for 3-4 weeks. The most recognised side effect of treatment is gastrointestinal distress. Thyroid function tests should be performed during treatment as suppression can occur.
56- A slimy, mucoid colony growing on Sabouraud’s agar at 37 degrees Celsius is observed to produce urease. The organism is:
A. Candida albicans
B. Cryptococcus neoformans
C. Candida glabrata
D. Candida tropicalis
E. Aspergilus flavus
►B
Cryptococcus neoformans is an encapsulated yeast with a worldwide distribution. Cryptococcosis is usually acquired by inhalation and subsequent dissemination to various organs including the meninges and the skin can occur. Immunosuppressed patients are particularly susceptible to infection. In approximately ten percent of disseminated cases, cutaneous lesions may develop. These present as acneiform papules or pustules and may progress to infiltrated plaques, nodules, or ulcers. Less commonly, cutaneous lesions can represent primary cutaneous cryptococcosis via direct inoculation of organisms into the skin. Diagnosis is made by direct microscopy and India ink stains can aid visualization. The organisms are large, encapsulated budding yeasts. In histopathologic sections, capsules stain with alcian blue and mucicarmine stains. In culture, C. neoformans is distinguished by production of urease as well as the ability to pigment on Guizotia seed medium. Colonies are described as slimy and mucoid. Serologic antigen-detection assays are also available. Treatment of disseminated cryptococcosis includes amphotericin combined with flucytosine.
57- Which of the following statements regarding lobomycosis is FALSE?
A. Itraconazole is the treatment of choice
B. It resembles a ―chain of coinsǁ on histopathology
C. It is also known as ―keloidal blastomycosisǁ
D. Lacazia (formerly Loboa) loboi is the number one cause
E. The infection also occurs in dolphins
►A
Lobomycosis, also know as keloidal blastomycosis is caused by Lacazia loboi (formerly Loboa loboi). It is endemic to Brazil and the Caribbean and is associated with dolphins. Clinically, the disease presents with painless keloidal papules and plaques, ulcerative lesions and/or verrucous lesions. Biopsy specimens display multiple budding thick-walled cells attached with a bridge, often referred to as a ―chain of coins.ǁ Surgical treatment is necessary as antifungal medications are ineffective.
58- Medlar bodies are diagnostic of infection with which organism?
A. Blastomycosis
B. Chromomycosis
C. Coccidiomycosis
D. Histoplasmosis
E. Sporotrichosis
►B
Chromoblastomycosis, or chromomycosis, is a cutaneous mycosis caused by dematiaceous, or pigmented, fungi. Several fungal species are associated with this infection including Phialophora verrucosa, Fonsecaea pedrosoi, F compactum, Exophiala (Fonsecaea, Wangiella) dermatitidis and Cladosporium carrionii. Infection is typically trauma-induced and involves the lower extremities. Lesions appear as verrucous papules, nodules and plaques, with occasional elephantiasis resulting from lymphatic blockage. Histopathologic findings include pseudoepitheliomatous epidermal hyperplasia and a dermal infiltrate composed of epithelioid histiocytes, multinucleated giant cells, and small clusters of inflammatory cells including plasma cells, neutrophils, eosinophils and lymphocytes. The characteristic histopathologic feature is the presence of dark brown, thick-walled, ovoid spheres in clusters or chains referred to as “copper pennies” or Medlar bodies. They are visible without the use of special stains.
Coccidioidomycosis
Angioinvasive-fungus-fusarium
protothecosis
tinea-nigra
onychomycosis
phaeohyphomycosis
eumycetoma
tinea-corporis
tinea-capitis
candidiasis
tinea-versicolor
histoplasmosis
blastomycosis
cryptococcosis
