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| ==Cryptococcus neoformans==
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| Keywords (immunodeficiency): HIV, antiretroviral therapy, oropharyngeal thrush, hepatosplenomegaly, central umbilication, central necrosis, hemorrhagic crust.
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| *Cryptococcus neoformans is an encapsulated yeast
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| *Occurs in patients with advanced HIV (CD4<100/mm3)
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| *The most common manifestation is meningoencephalitis
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| *Pulmonary and/or disseminated disease may occur
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| *Cutaneous cryptococcosis considered as a marker of disseminated disease
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| *Rapid onset (2 weeks) of multiple widespread papular lesions with central umbilication
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| *Diagnostic clue is the presence of a small area of central hemorrhage or necrosis
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| *Resembles molluscum contagiosum
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| *Most common areas affected are head and neck
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| *Disseminated infections can affect liver, lymph nodes, peritoneum, adrenal gland, and eyes
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| *Diagnosis
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| **Biopsy of the lesion
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| **Histopathological examination after staining (periodic acid-Schiff, Gomori methenamine silver nitrate)
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| **Hyperplasia of the overlying dermis with underlying granulomas surrounding encapsulated yeasts
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| **Fungal blood culture is often positive in severe disseminated cryptococcal disease but a biopsy is more sensitive and specific than blood culture (because untreated HIV patients have multiple ongoing opportunistic infections)
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| **Serum antigen testing can be useful for the diagnosis
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| **The most common wrong answer is skin scrapings with a microscopic evaluation which is used for the diagnosis of fungal infections as tinea or candidiasis.
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| *Treatment:
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| **>/= 2 weeks of IV amphotericin B plus oral flucytosine
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| **Followed by a year of oral fluconazole (higher dose for 8 weeks, then maintenance)
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| DD:
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| *Kaposi Sarcoma:
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| **Primarily presents in homosexual men(men with HIV who are sexually active with other men)
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| **Red or purple papules with no necrosis
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| *Disseminated Mycobacterium avium complex:
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| **Common opportunistic infection
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| **Affects patients with advanced AIDS
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| **Presents as fever, night sweats, abdominal pain, diarrhea, weight loss
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| **Cutaneous lesions are uncommon and are usually nodular and ulcerating
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| *Pyoderma gangrenosum:
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| **Rare neutrophilic dermatitis
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| **Associated with inflammatory bowel disease and inflammatory arthritides
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| **Presents as a tender papule that degrades into a bluish, violaceous ulcer
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| *Basal cell carcinoma
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| **Single, pink, flesh-colored papules
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| **Arise slowly
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| ==Tuberculosis==
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| *Active pulmonary tuberculosis
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| **Due to reactivation of the latent disease
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| **Epidemiologic risk factors
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| ***Substance abuse
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| ***Homelessness
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| ***Birth in a TB-endemic region
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| **Clinical manifestations
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| ***Fever, cough >2 weeks, weight loss
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| Diagnosis:
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| *Chest x-ray
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| **signs of active disease (upper lobe cavitation 970-80%), hilar lymphadenopathy, or pleural effusion.
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| **Definitive diagnosis of suspicious x-ray finding by isolation of Mycobacterium tuberculosis in body fluid or tissues (lung, pleura)
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| **Sputum sampling (acid-fast bacilli smear and culture)
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| ***Least invasive and costly route for microbial confirmation
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| ***Three single sputum samples (spontaneous or induced) are submitted in 8- to 24-hour intervals with at least 1 early-morning sample
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| ***Sputum should be sent for acid-fast bacillus smear, mycobacterial culture, and nucleic acid amplification testing.
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| **Tuberculin skin test and interferon-gamma release assay
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| ***both can only support the diagnosis and if positive suggest exposure
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| ***Can't distinguish between active and latent disease
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| **Bronchoscopy with bronchoalveolar lavage
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| ***More invasive and expensive than sputum sampling
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| ***Reserved for patients who are
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| ****Unable to produce adequate expectorated or induced sputum
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| ****Have negative sputum studies with a high suspicion for active TB
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| ****Have possible alternate diagnosis that requires bronchoscopy for evaluation
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