Punch Biopsy: What It Diagnoses & What It Doesn't

Question
Can a punch biopsy determine a viral rash? Does it need to be stated on the lab form, to test for viral skin condition or can they tell just by the structure of the skin as to weather the rash is viral, bacterial or fungal?
Thank you

Answer
Hi Elle,
A punch biopsy is commonly used to diagnose tumours (benign or malignant) and inflammatory skin conditions such as psoriasis. They aren't usually used for identifying pathogenic organisms - be they viral, bacterial or fungal. During a punch biopsy a core of tissue is taken from the affected area and is examined under the microscope using various stains depending on what the pathologist is looking for. In order to diagnose a bacterial/viral/etc. infection a culture should be taken. This is a seperate test.
I hope this is helpful. If you have further questions please do not hesitate to contact me again.
Sam