• alternative name

• laboratory findings

• about the disease

• prevention

• treatment

• prognosis

Alternative name,  Gilchrist's disease; North American blastomycosis

Symptoms and signs.  Pulmonary form- patches of bronchopneumonia that appear, on chest film, to fan out from the hilum like a neoplastic growth. A dry hacking or productive cough, chest pain, fever, chills, drenching sweats, and dyspnea are initial symptoms. Disseminated form- site of hematogenous spread includes skin, prostate, epididymis, and testis, bone subcutaneous tissue. The vertebrae, tibia and femur are commonly involved; swelling, heat and tenderness are present over the lesion. Genital tract lesions are characterized by painful swelling, typically of epididymis or deep perineal discomfort from prostatitis. Skin lesions begin as papules or papulopustules on exposed surfaces briefly and spread slowly. Painless miliary abscesses develop on the advancing borders. Irregular, wartlike papillae form on the surfaces. As the lesions enlarge, the center heals with a typical atrophic scar. A fully developed individual lesion appears as an elevated verrucous patch measuring >2 cm.  With an abruptly sloping, purplish-red, abscess-studded border.

Laboratory findings.  microscopic thick-walled yeast cells with single broad-based buds are seen in tissue biopsies; hyphae with small pear-shaped conidia on culture; chest X-ray may show nodules or pneumonia with cavities; Culture and identification of B. dermatitidis – a thick-walled budding yeast, without a capsule, seen on direct examination of pus, sputum or exudate. Hyphae with small pear-shaped conidia are visible on culture.

About the disease.  Blastomyces dermatitidis causes blastomycosis. B. dermatitidis is a dimorphous fungus that exists as a mold in soil and as a yeast in tissue. The yeast is round with a doubly refractive wall and a single broad-based bud.

The fungus is endemic in North and Central America and in Africa. It grows in moist soil rich in organic material, forming hyphae with small pear-shaped conidia. Inhalation of the conidia causes human infection.

Infection occurs mainly via the respiratory tract. Asymptomatic or mild cases are rarely recognized. Dissemination may result in ulcerated granulomas of skin, bone or other sites.

Prevention.  condition is rare except in immunocompromised patients; avoid travel to areas where the disease is endemic

Treatment.  aimed at controlling the infection with medication; amphotericin B, ketoconazole, or other antifungal agents can be prescribed for all forms of the disease; itraconazole is the drug of choice; Amphotericin B for severe disease and surgical excision; periodic follow-up recommended to identify cases of relapse; Itraconazole is the drug of choice. Amphotericin should be used for severe cases. Surgical excision may be helpful.

Prognosis.  presentation of limited skin lesions has the best prognosis; when left untreated, this condition is progressive and can be fatal; possible complications include relapsing infection and large abscesses