Revenue Cycle Insider

Question: A patient came in stating they noticed a gradual thickening and discoloration of their toenails over the past few months. They experienced no discomfort accompanying the change in appearance. There was no evidence of ingrown toenails or any other abnormalities of the nails. The patient was diagnosed with onychomycosis. How should I code this?

Georgia Subscriber

Answer: Another name for onyschomycosis is tinea unguium, which is a fungal infection of the toenail coded as B35.1 (Tinea unguium). 

If the patient had simply presented with symptoms that were similar to a fungal infection of the toenail such as itching or flaking of the surrounding skin or thick nails, but no exact diagnosis had been reached, you would code for the symptoms and signs instead, using codes like the following:

• R21 (Rash and other nonspecific skin eruption). This code can be used if the patient has a rash associated with the suspected fungal infection.
• R23.8 (Other skin changes). This code can be used if there are noticeable changes to the skin around the nail due to irritation.

Keep in mind: If you’re conducting a fungal culture, you may use codes like 87101 (Culture, fungi (mold or yeast) isolation, with presumptive identification of isolates; skin, hair, or nail) or 87220 (Tissue examination by KOH slide of samples from skin, hair, or nails for fungi or ectoparasite ova or mites (eg, scabies)).

The choice of code will depend on the specific circumstances and whether the cultures are being analyzed in your own lab. However, if the samples are being sent to an external lab by your practitioner, these codes cannot be used.

Lindsey Bush, BA, MA, CPC, Production Editor, AAPC