B40.3

Clinical Causes: Primarily caused by exposure to Blastomyces dermatitidis spores, which are found in moist, temperate environments such as wooded areas, rivers, and soil. Inhalation of spores is common, but skin infections occur when spores directly infect the skin through cuts or abrasions. Activities involving soil disruption, outdoor work, or exposure to decaying organic matter increase risk. People with weakened immune systems are more susceptible to developing cutaneous blastomycosis after exposure. Travel to or residence in regions where blastomycosis is endemic, especially the southeastern, south-central, and midwestern United States.

Key Symptoms: Initial skin lesions often begin as painless, verrucous (wart-like) plaques or ulcers with raised or irregular borders. Lesions may have a granulomatous appearance, sometimes with crusting or scabbing. Over time, lesions can enlarge, become nodular, or form abscesses that drain pus. Affected areas are commonly on the face, neck, arms, or other exposed skin regions. In some cases, multiple skin lesions are present simultaneously. Symptoms may include mild discomfort or tenderness, but often the primary concern is the appearance of skin changes.

Diagnosis Path: Diagnosis involves a combination of clinical examination, medical history, and laboratory tests. Skin biopsies are commonly performed to examine tissue samples under a microscope for fungal elements. Fungal cultures can identify Blastomyces dermatitidis, and molecular tests may aid in diagnosis. Additionally, imaging studies or blood tests could be recommended if systemic involvement is suspected. Correct identification is crucial to differentiate blastomycosis from other skin conditions like bacterial infections or skin cancers.

Treatment Protocols: Treatment typically involves antifungal medications prescribed by healthcare professionals. Common options include itraconazole for less severe cases or amphotericin B for more extensive or resistant infections. The duration of therapy can range from several months to ensure complete elimination of the fungus. Adjunctive measures, such as wound care and managing secondary bacterial infections, may also be necessary. Follow-up evaluations are essential to monitor response to treatment and prevent recurrence.