Andrews

Question 1

Meaning of Mycosis?

Answer 1

A mycosis (plural: mycoses) is a fungal infection of animals, including humans.[1]

Mycoses are common and a variety of environmental and physiological conditions can contribute to the development of fungal diseases. Inhalation of fungal spores or localized colonization of the skin may initiate persistent infections; therefore, mycoses often start in the lungs or on the skin

Question 2

Describe mold

Answer 2

Mold is the environmental form of fungi and is comprised of multicellular filaments called hyphae. Multiple hyphae collectively are called mycelium and at the ends are conidia, asexual spores formed by differentiation. This is the portion of mold that is inhaled and causes pulmonary disease. At room temp they form rough colonies when cultured.

Question 3

Describe yeast

Answer 3

Yeast is the tissue form of fungi and is its unicellular form. Its reproduction is asexual via spores through asymmetric budding. The formation of spores allows for dissemination and survival in a hostile environment. At body temp they form smooth colonies that can appear slimy or mucoid.

Question 4

Define Hyphae

Answer 4

Long branching filamentous structures of fungus. The main mode of vegetative growth and collectively called mycelium

Question 5

Define Conidium

Answer 5

Asexually produced fungal spores that are the source of dispersal, located at the ends of the hyphae

Question 6

Define sporangium

Answer 6

Sporangium (pl – sporangia) = Single or many celled balloon-like structure in which spores are produced

Question 7

Define hyaline and dematiaceous

Answer 7

Hyaline = colorless fungi
Dematiaceous = brown to black fungi

Question 8

Causative organism for Basidiobolomycosis?

Answer 8

Basidiobolus ranarum

Question 9

Findings seen in Basidiobololmycosis?

Answer 9

enviromental saprophyte, found in tropics

forms plainless, indurated subq nodule or swelling on thigh/butt

Question 10

What is Conidiobolus coronatus?

Answer 10

similar to basidiobolomycosis (related organism)

affects face

Question 11

What is Protothecosis

Answer 11

not a true fungus

• Prototheca wickerhamii
• often seen with exposure to contaminated water
• Solitary cutaneous plaques (sometimes eczematous), nodules or ulcers, as well as olecranon bursitis

Difficult to treat
Surgical excision and systemic antifungals (e.g. amphotericin B) are more effective in immunocompetent hosts

Question 12

Organism in sporotrichosis?

Answer 12

Sporothrix schenckii

Question 13

3 types of sporotrichosis?

Answer 13

Lymphocutaneous (regional lymphangitic)- naïve hosts
Fixed cutaneous- if prior exposure
Disseminated or pulmonary- immunocompromised host

Question 14

Findings on culture of sporotrichosis?

Answer 14

Grows on Sabouraud dextrose agar (SDA)
25C: Rapidly shows a white colony, wrinkled and folded, tan to black over time

37C: Slow growing, whitish, pasty yeast like colonies and cigar shaped budding yeasts

Question 15

Findings on biopsy of sporotrichosis?

Answer 15

Palisading granulomatous dermatitis surrounding a stellate suppurative abscess
Asteroid bodies – esosinophilic material around central yeast cell
PAS +, “cigar bodies” -round yeast cells (difficult to identify) – staining with fluorescent labeled antibodies may aid in recognition

Question 16

Tx of sporotrichosis?

Answer 16

• topicals not effective
• Potassium Iodine
• Itraconazole

Question 17

What is the Wolff-Chaikoff effect?

Answer 17

the effect when increasing doses of exogenous iodide inhibit thyroid hormone production leading to hypothyroidism

Question 18

Differential for sporotrichoid lesions?

Answer 18

Mnemonic “SLANT” 
Sporotrichosis, S. aureus, S. pyogenes, S. boydii
Leishmaniasis
Atypical mycobacteria (m. marinum)
Nocardiosis
Tularemia, Toxoplasmosis, Tuberculosis

Glanders (burkholderia mallei)
Dimorphic and opportunistic fungi
Opportunistic fungi in IC hosts (fusarium, alternaria spp)
Cat scratch disease
Anthrax and Cowpox
Acanthamoeba spp.

Question 19

What are the three different types of mycetoma (fungal tumors)?

Answer 19

It is a granulomatous infection of dermal and subcutaneous tissue that may extend to muscle or even bone and is due to implantation. Mycetoma is differentiated from other mycoses by its characteristic draining sinuses containing grains (sclerotia, sulfur granules) and local edema.

1. Actinomycetoma - filamentous aerobic and anaerobic bacteria i.e. Nocardia brasiliensis, Actinomadura madurae
   More common 3:1
2. Eumycetoma - true fungi
3. Botryomycosis - true bacteria, s. aureus, pseudomonas

Question 20

Where are on the body do mycetomas infect?

Answer 20

Granulomatous infection of dermis and subcutaneous
Differs from other mycoses – slowly progressive, chronic, subcutaneous infection, swelling with draining sinuses (sulfur granules) (sclerotia)
Instep of the foot, painless, firm nodule with tissue destruction
May involve the underlying fascia and bone
Enter by traumatic/penetrating inoculation, (MC on foot)
Toe webs, hands, arms, chest, jaw, buttocks
Unexposed sites are almost always actinomycetomas

Question 21

What is the course of infection with mycetomas?

Answer 21

Foot is m.c. site of infection
Followed by the hand, trunk and scalp
Typically unilateral and begins as a painless papule
Once SubQ tissues infected -> surrounding soft tissue swells and starts to form purulent draining sinuses
Drainage contains the characteristic grains (sclerotia)
Represent compact masses of fungal colonies
Vary in size from minute to almost a centimeter in diameter
Invasion of deeper tissues then ensues -> sometimes cavities are formed within involved bone
Generally asymptomatic!!

Question 22

What is seen on biopsy and culture of actinomycetomas?

Answer 22

Culture
Brain-heart infusion agar and sabouraud dextrose agar, 0.5% yeast extract
Biopsy
Thin branching gram + filaments 1-2 micrometers thick

H + E: PEH and suppurative and granulomatous inflammation with stellate abscesses containing grains (asteroid bodies)
Stain well with Giemsa, Brown-Brennen

Question 23

What is seen on biopsy and culture of eumycetoma?

Answer 23

Culture
Sabouraud dextrose agar, 0.5% yeast extract (hyphae and chlamydoconidia)
Biopsy
Thick filamentous hyphae 2-5 micrometers thick
Stain well with PAS, Gomori methenamine silver

Question 24

What are the treatments for eumycetoma and actinmycetomas?

Answer 24

Actinomycetoma
Responds to antibiotics
Bactrim, sulfadiazine, sulfones, dapsone
A. israelii: PCN in large doses is curative
N. asteroides & N. brasiliensis: Sulfonamides
Rifampin & co-trimoxazole have been used
Severe refractory cases may need impenem

Eumycetoma
Early, surgical removal of area, amputation necessary in severe cases
+ Antifungal treatment (itraconazole, fluconazole, posaconazole)
Relapses are common

Question 25

What are the three characteristics that make up a mycetoma?

Answer 25

Tumefaction (edema) Sinus tracts Granules (expelled organisms)

Question 26

What are the causes of chromoblastomycosis?

Answer 26

Caused by one of 6 dematiaceous fungi: (melanin) “Fond of Pedro’s Compact Monochromatic Car” “Fun with PCR” Fonsecaea pedrosoi (most common, 90%) Fonsecaea compacta Fonsecaea monophora Phialophora verrucosa Cladophialophora carrionii Rhinocladiella aquaspera (isolated cases) Exophiala spinifera & jeanselmei

Question 27

What does chromoblastomycosis look like clinically?

Answer 27

Starts as small papule or warty growth  Foot or lower leg Typically unilateral Verrucous (cauliflower-like lesions) (TH2 immunological response!) Granulomatous plaque, annular with central atrophy, scarring (TH1 imunological response) Direct extension spread and satellite lesions Regional lymphadenopathy (2° bacterial infection) Usually no constitutional symptoms Rarely – Squamous cell carcinoma develops in long standing lesions

Question 28

How is chromoblastomycosis diagnosed?

Answer 28

Histology PEH, intraepidermal abscess, granulomatous inflammation Pigmented fungal sclerotic bodies (Medlar bodies “copper pennies”), often seen with embedded splinter and are pathognomonic Brown, round thick walled cells Culture Black, velvety, heaped up colonies (all produce melanin) - Pseudoepitheliomatous hyperplasia, intraepidermal abscesses, and suppurative and granulomatous inflammation within the dermis are the typical histologic findings. Round, pigmented bodies, which are said to resemble “copper pennies” (6 to 12 microns), are present in the dermis, both extracellularly and within giant cells. These are unique to chromoblastomycosis and are also known as “Medlar bodies” or sclerotic bodies[2

Question 29

What fungus causes lobomycosis?

Answer 29

Locazia loboi

Question 30

Describe clinical manifestation of lobomycosis.

Answer 30

Chronic fungal infection characterized by cutaneous nodules that resemble keloids. May involve regional lymph nodes.

Question 31

What will the biopsy show for lobomycosis?

Answer 31

Biopsy Atrophic epidermis Thick walled refractile spherules, only one or two buds Cellular granulomatous infiltrate: PEH, histiocytes, giant cells, lymphocytes; atrophy Can not be cultured normally Can grow on mouse footpads

Question 32

What is the treatment of lobomycosis?

Answer 32

Recurrence is common! Surgical excision, cryotherapy Antifungals often ineffective Itraconazole 100mg/day and Clofazamine 100mg/day some benefit

Question 33

What organism causes Rhinosporidiosis?

Answer 33

Rhinosporidium seeberi

Question 34

What are the clinical manifestations of Rhinosporidiosis?

Answer 34

Polypoid disease involving mucosal surfaces Nasal mucosa, conjunctival, oral, genital (condylomata) Small papillomas develop into large polyps, pedunculated tumors with fissured warty surface Grayish white flecks on tissue (transepithelial elimination of large sporangia) Conjunctival – small, pinkish papillary nodules that enlarge, darken, and become lobulated

Question 35

What is the treatment of Rhinosporidiosis?

Answer 35

Excision or electrosurgery is most common Antifungals little help May try cipro (works against M. aeruginosa)

Question 36

What will biopsy show of Rhinosporidiosis?

Answer 36

Diagnosis: Biopsy (histology) – organism does NOT grow in culture Spherules (7-10μm) in large cystic sporangia (300μm) Endospores are rough like raspberries Granulomatous response 50% Transepithelial elimination is common

Question 37

What are the 3 forms of infection with Coccidiomycosis?

Answer 37

Primary pulmonary Inhalation of dust laden with arthroconidia Disseminated (coccidiodal granuloma) <1% of infections Immunosuppression increases risk of dissemination Skin lesions in 15-20% of disseminated cases Primary Cutaneous Rare

Question 38

What are the clinical manifestations of primary pulmonary infection with coccdiomycosis?

Answer 38

Primary pulmonary infection: 60% infected are asymptomatic Mild respiratory infection, low grade fever, flu-like sx Incubation 10 days - weeks Fever, pleuritic CP, HA, resp distress, anorexia, malaise, myalgias Large % develop CXR findings Initial morbilliform eruption may appear Within weeks may develop allergic skin manifestations Erythema nodosum Erythema multiforme Most recover spontaneously

Question 39

What are the findings on histology for coccdiomycosis?

Answer 39

Diagnosis: CXR KOH Biopsy Spherules, unencapsulated, thick refractile wall and granular interior, average 20μm Stain well with PAS, GMS and H&E Culture Highly infectious (only in labs with hoods!!) SDA  Dimorphous, seen at both temperatures Fluffy white-tan colony Mycelia have 90° branching and septated hyphae Spherical bodies, many thick-walled barrel-shaped

Question 40

What are the skin findings of coccdiomycosis?

Answer 40

``` Cutaneous Patterns Toxic erythema (pulmonary) Diffuse morbilliform eruption early in disease Hypersensitivity reaction (pulmonary) Erythema nodosum Erythema multiforme Primary cutaneous Nodules that ulcerate ``` Secondary cutaneous (disseminated) Papules, pustules, abscesses, granulomatous plaques (may look like molluscum in HIV patients) Often on central face, NL folds

Question 41

What is the DDx of parasitized macrophages?

Answer 41

His GRL Pen Histoplasmosis- H.capsulatum Penicilliosis- P. marneffei Granuloma inguinale- Calymmatobacterium granulomatis Rhinoscleroma- Klebsiella rhinoscleromatis Leishmaniasis- Leishmania spp

Question 42

How do we diagnose Histoplasmosis?

Answer 42

Diagnosis Biopsy 2-3μm round bodies within cytoplasm of macrophages Single or budding with thin isthmus between buds Pseudocapsule (artifact), halo (rim of clearing) around organism African: 10-13μm organisms within multinuclear giant cells Organisms stain with Giemsa, PAS or GMS Cultures Blood, sputum, bronchial washings, spinal fluid, lymph node smears, ulcers SDA, Mycosel, brain-heart infusion (blood added) 25C: Fluffy white, turns tan, septate hyphae, pear-shaped microconidia, thick-walled echinulate macroconidia 37°C: moist yeast colony, small, round-oval budding cells Immunology Best test is urinary ELISA Histoplasmin skin test, complement fixation test > 1:32 = active or recent infection Culture remains the gold standard

Question 43

DDx Pseudoepitheliomatous Hyperplasia?

Answer 43

``` Atypical mycobacterium Actinomycosis Blastomycosis Paracoccidiosis Coccidioidomycosis Chromomycosis Protothecosis Sporotrichosis Halogenoderma ```

Question 44

Differential for Molluscum-like lesions

Answer 44

“CCHIP” Cryptococcosis Coccidioidiomycosis Histoplasmosis Penicillium