Cutaneous protothecosis: a case report and review of the literature

Area of Science:

• Medical Mycology
• Infectious Diseases
• Dermatology

Background:

• Protothecosis is a rare infection caused by Prototheca algae.
• Human infections, primarily with Prototheca wickerhamii, are infrequently reported, limiting understanding of its pathogenesis.
• While cases occur in immunocompetent individuals, immune compromise is often a contributing factor.

Observation:

• An 81-year-old woman with a history of nonmelanoma skin cancers presented with persistent leg lesions.
• Lesions were unresponsive to topical treatments like diclofenac sodium gel and 5-fluorouracil cream.
• Dermal abscesses containing characteristic Prototheca wickerhamii organisms were identified via skin biopsy.

Findings:

• Biopsy revealed spherical, fungus-like organisms within a dermal abscess.
• Periodic acid-Schiff staining confirmed the presence of 6- to 10-microm organisms with internal septations.
• Morphological characteristics were consistent with Prototheca wickerhamii.

Implications:

• This case expands the clinical presentation of Prototheca wickerhamii infections.
• It underscores the importance of considering rare pathogens in persistent skin lesions, especially in immunocompromised or elderly patients.
• Further research into Prototheca wickerhamii pathogenesis and treatment is warranted.