Pathology/Lab Coding Alert

Question: Our lab receives a toenail excision with some attached skin for a fungal test. We examine the specimen using a KOH preparation test. Should we report a surgical pathology tissue exam in addition to the KOH test?

Ohio Subscriber

Answer: Because you don't give any indication that a pathologist performed a gross and microscopic exam apart from the potassium hydroxide (KOH) test, you should not report a surgical pathology exam for skin or an unlisted specimen (toenail), such as 88304 (Level III -- Surgical pathology, gross and microscopic examination, skin -- cyst/tag/debridement).

Instead: Code the KOH test based on the lab method, your payer, and your lab certification. Typically, a "KOH preparation test" involves placing the skin/nail specimen on a slide with KOH solution and heating the specimen to dissolve the skin and nail cells. The process will leave fungal cells on the slide, if present, and the cells can be seen using a microscope, possibly with a stain.

The code for this test is 87220 (Tissue examination by KOH slide of samples from skin, hair, or nails for fungi or ectoparasite ova or mites [e.g., scabies]). Medicare payers may require you to use Q0111 (Wet mounts, including preparations of vaginal, cervical or skin specimens) or Q0112 (All potassium hydroxide [KOH] preparations), depending on your exact methodology.