Cultures are necessary to make the diagnosis of onychomycosis.

• A. True
• B. False
• C. Sometimes true
• D. Not specified

Answer: (B)

Cultures are not required to diagnose onychomycosis. You can establish the diagnosis from the nail’s clinical appearance combined with direct demonstration of fungal elements in the nail, typically using a KOH prep or a histopathology stain (like PAS). Cultures are useful to confirm the fungal organism and to guide treatment choices, especially when the presentation is unclear, when non-dermatophyte molds or yeasts are involved, or when systemic therapy is being considered and species identification may influence drug selection. However, culture results take time, can be falsely negative, and are not necessary for every case. In practice, diagnosis often rests on clinical assessment plus direct microscopy, with culture as an adjunct when confirmation or organism identification would change management.