Organisms in an aspirate from an ulcerated mass: etiologic agent or mass-querade?

Area of Science:

• Veterinary Pathology
• Mycology
• Clinical Cytology

Background:

• Fine-needle aspiration (FNA) is a common diagnostic technique in veterinary cytology.
• Differentiating true pathogens from contaminants is crucial for accurate diagnosis.
• Yeast infections can present with varied cytologic features.

Observation:

• A dermal mass in a puppy showed inflammation and extracellular organisms on cytology.
• Organisms were described as yeast-like, leading to a cytologic diagnosis of mycotic dermatitis.
• Histopathology revealed inflammation but no definitive infectious agents.

Findings:

• The yeast, Rhodotorula minuta, was identified from the cytologic sample.
• Rhodotorula minuta was also isolated from a nearby cactus, suggesting environmental contamination.
• Histopathology did not support a diagnosis of mycotic dermatitis, contrasting with cytologic findings.

Implications:

• Cytologic findings of Rhodotorula minuta in a dermal lesion were attributed to sample contamination.
• This case highlights the challenge of distinguishing contaminants from true pathogens in cytology.
• Careful correlation of cytologic, histologic, and environmental data is essential for diagnosing opportunistic infections.