Transcript Blastomyces dermatitidis

cc: cough, fever, dyspnea and wart-like growth on neck
HPI: 35-year old otherwise healthy, nonsmoker, male presents to
the clinic with complaints of intermittent cough, low-grade fever,
and difficulty breathing that has persisted for the past few
months. Additionally, he has noticed a nontender wart-like
growth on his neck that has increased in size over this period.
He reports 5 lb weight loss and has experienced some
occasional joint stiffness throughout the day. He drinks 2-3
beers a week, tried marijuana 5 years ago, and denies any IV
drug use or time spent in jail. He has worked as a landscaper
for the past 10 years and recently moved from Missouri.
Physical Exam
vs: temp-38.6°C (101.5°F), BP-128/82, HR-98, RR-20
General-no acute distress
HEENT-normocephalic atraumatic
Neck-supple, no thyromegaly, no cervical lymphadenopathy
CV-tachycardic, regular rhythm, normal S1/S2, no murmurs, rubs, or gallops
Pulmonary-bilateral fine inspiratory crackles
Abdomen-soft, nontender, nondistended, + BS, no hepatosplenomegaly
Extremities-no cyanosis, clubbing, or edema
Skin-4-5 cm raised, nontender, verrucous like lesion located on right side of
neck just behind the ear
Physical Exam: Skin findings
Differential Diagnosis?
Differential Diagnosis
Pulmonary symptoms
• Blastomycosis
• Histoplasmosis
• community acquired bacterial or viral pneumonia
• Lung malignancy
• Tuberculosis
Cutaneous lesion
• squamous cell carcinoma
• pyoderma gangrenosum
• keratoacanthoma
• mycosis fungoides
• actinomycosis
What labs/imaging would you like to order?
Labs:
• CBC, electrolytes
• ALT/AST/alkaline phosphatase/bilirubin
• BUN/SCr
• UA
• PPD
• Sputum sample and culture
• Lesion biopsy
Imaging:
• CXR
Lab Results
WBC
Hemoglobin
Platelet count
11,000/µL
10.9 g/dL
230,000/µL
Sodium
Potassium
Chloride
Bicarbonate
BUN
Creatinine
140 meq/L
4.1 meq/L
95 meq/L
23 meq/L
18 mg/dL
1 mg/dL
ALT/AST/alk phos/bilirubin
normal
Urinalysis
PPD
normal
negative
Sputum
Lesion bx
broad-based budding yeast
noncaseating granuloma
Results: Imaging-CXR
What is your diagnosis?
Blastomycosis
• Is a systemic pyogranulomatous infection
• Acquired through inhalation of the conidia of the
thermally dimorphic fungus, Blastomyces dermatitidis.
• Lungs are most commonly affected, though almost
every organ may become involved through
hematogenous dissemination
• May be an asymptomatic infection or develop into an
acute or chronic pneumonia
Blastomycosis
Epidemiology:
• Most cases reported in North America
• Endemic areas include southeastern and south-central
states bordering the Mississippi and Ohio River basins
as well as the Great Lakes area.
• Annual incidence 40/100,000 in endemic areas
• In endemic areas middle-aged men with outdoor
occupations at greatest risk
• Exposure to ground soil associated with infection
Blastomycosis
Etiology:
• Blastomyces dermatitidis
• There are 2 serotypes based on the presence or
absence of A antigen
• Exhibits thermal dimorphism, mycelial phase at room
temp and yeast phase at 37°C.
• Yeast cells are usually 8-15µm in diameter, have thick
refractile cell walls, and are multinucleate
• Reproduce by single, large, broad-based bud.
Blastomycosis
1. Broad-based budding
yeasts
2. Thick, double refractile
cell wall
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2
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Blastomycosis
Pathophysiology:
• Infection begins with inhalation of Blastomyces dermatitidis
• Conidia may be killed through phagocytosis by
polymorphonuclear leukocytes, monocytes, and alveolar
macrophages
• If conidia, the infectious stage, is not killed it may convert to
the yeast phase in the tissue
• Yeast form is more resistant to phagocytosis and killing due
to its size and thick cell wall thereby contributing to infection
• Primary acquired host defense against B. dermatitidis is
cellular immunity mediated by antigen-specific T cells and
activated macrophages.
Blastomycosis
Extrapulmonary manifestations:
1.
skin-second most common manifestation after pneumonia,
characteristic finding is verrucous lesion, with irregular border. It
may look similar to squamous cell carcinoma.
2. Bone and joint-osteomyelitis
3. Genitourinary system-prostatitis, epididymoorchitis, asymptomatic
pyuria
4. CNS-uncommon in immunocompetent hosts; however, those that are
immunocompromised it may present as meningitis, epidural abscess,
or intracranial abscess
*Blastomycosis has also been reported in lymph nodes, liver, spleen,
breast, adrenal gland, thyroid, eye, and oral mucosa
Blastomycosis
Examples of extrapulmonary manifestations:
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1,3. Cutaneous
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Blastomycosis
2. Blastomyces osteolytic
lesion
4. CNS Blastomycosis
5. Intramuscular
Blastomycosis
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Blastomycosis
Treatment:
• Therapeutic regimen should be based on the clinical
form and severity of disease, and the immune status of
patient.
• Immunocompetent patient with mild to moderate
pulmonary or non-CNS disease-treat with itraconazole
for 6-12 months
• Immunocompromised, CNS disease, or continued
disease progression with itraconazole -treat with
Amphotericin B
Blastomycosis
Follow-up:
• Monitor patient several years for relapse
Prognosis:
• Treatment with itraconazole in immunocompetent
patient results in approx 90-95% response rate
• Infections that relapse after initial itraconazole course
typically respond well to 2nd treatment course.
References:
1 "Blastomycosis." Quick Answers to Medical Diagnosis and Therapy:
http://www.accessmedicine.com/quickam.aspx
2 Chapman S.W., Sullivan D.C. (2012). Chapter 201. Blastomycosis. In D.L. Longo,
A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's
Principles of Internal Medicine, 18e. Retrieved November 21, 2012 from
http://www.accessmedicine.com/content.aspx?aID=9110719.
3 Bradsher Jr., RW. Clinical manifestations and diagnosis of blastomycosis. In:
UpToDate, Kauffman, C, Thorner, A, eds. UpToDate, Waltham, MA, 2012
4 Bradsher Jr., RW. Treatment of blastomycosis. In: UpToDate, Kauffman, C,
Thorner, A, eds. UpToDate, Waltham, MA, 2012
5 Centers for Disease Control and Prevention. “Histopathology B. dermatitidis.”
Online image. http://www.cdc.gov/fungal/blastomycosis/. Accessed on Nov 21,
2012.
6 MedicaLook. “Blastomycosis.” Online image.
http://www.medicalook.com/Skin_diseases/Blastomycosis.html. Accessed on Nov
21, 2012.