Nail Unit Biopsy - CPT Code 11755
The nail unit includes: nail plate, nail folds, nail bed, and/or nail matrix. These biopsies aid in the characterization of subungual and periungual masses, pigmented lesions, and nail disorders. Similar to CPT codes 11100 and 11101, the nail unit biopsy code does not denote a single biopsy technique, but rather, any deliberate method of sampling tissue for histopathologic examination. As is typically the case for biopsies of all types, these procedures are intended to guide therapy and not necessarily to be therapeutic in and of themselves.

When comparing the techniques of culture, KOH preparation, and histologic examination, by far the most sensitive method for diagnosing onychomycosis is histologic examination augmented by a periodic acid-Schiff (PAS) reaction. In addition to the histologic examination's superior sensitivity, this technique is much more rapid and allows dermatopathologists to assess for alternate causes of nail dystrophy such as psoriasis, onychoschizia, and trauma. Regardless of whether CPT 11755 is used in this context, PAS reaction is the preferred test for the characterization of nail disorders. New guidance on the use of code 11755 has been issued by the American Medical Association (AMA). We will be providing more information in future articles.

Cutaneous (Punch) Biopsy - CPT Codes 11100 and 11101
All biopsies not taken by excision or shave technique are coded as 11100. These techniques do not necessarily require anesthesia (though of course it would be used for punches) and there is no mandate for the inclusion of deep tissues within the sample. In general, this code should be used whenever a small part of a larger lesion is sampled for histopathology. When performing biopsies on a dermatitis (“rash”), the first biopsy is coded as a CPT 11100. Any additional biopsies are coded as CPT 11101. Many clinicians choose to treat patients with a non-specific dermatitis empirically with topical anti-inflammatory agents +/- a keratolytic. Clinicians should be aware that the majority of pedal dermatitides are NOT in fact tinea. Patients are then brought back in 1-2 weeks for a follow-up visit at which time if resolution has not been attained, a biopsy is performed. In this context, 3.5-4.0mm disposable punches provide adequate tissue for histologic examination, though smaller punches may be preferred for weight-bearing surfaces. Whether used for neoplastic conditions or those which are inflammatory (i.e. dermatitis), biopsies are simple, reimbursable procedures which augment patient management.

When performing punch biopsies on pigmented lesions or non-pigmented neoplasms to rule out melanoma, squamous cell carcinoma, basal cell carcinoma, etc., the lesion is typically sampled during the initial visit.

The patient may be rescheduled in 1-2 weeks to discuss the biopsy results and, if necessary, for complete excision. Although 4mm punches are usually sufficient for diagnostic purposes, many clinicians choose to use larger punches (6-8mm) if such will allow for the total excision of smaller lesions.

Shave Biopsy - CPT Code Series 11300
Shave technique is an excellent option for elevated lesions (papules or nodules) and may be used to perform excisional biopsies on pigmented lesions of skin. To bill the CPT 11300 series of codes, anesthesia must be used and the sample must include dermis. To avoid under-billing, note that the following codes pertain to the size of the biopsy, not the lesion. Because formalin fixative causes tissue to shrink, it is advisable to document the biopsy size at the time of the procedure. Most shave biopsies will be about 1cm in diameter.

∗ Shave biopsy - leg
- CPT code 11301 (0.6-1.0cm)
- CPT code 11302 (1.1-2.0cm)
* Shave biopsy - foot
- CPT code 11306 (0.6-1.0cm)
- CPT code 11307 (1.1-2.0cm)

Excision - CPT Codes Series 11400 and 11600

* Excision of a benign lesion - leg
- CPT code 11401 (0.6-1.0cm)
- CPT code 11402 (1.1-2.0cm)

* Excision of a benign lesion - foot
- CPT code 11421 (0.6-1.0cm)
- CPT code 11422 (1.1-2.0cm)
* Excision of a malignant lesion - leg
- CPT code 11601 (0.6-1.0cm)
- CPT code 11602 (1.1-2.0cm)
* Excision of a malignant lesion - foot
- CPT code 11621 (0.6-1.0cm)
- CPT code 11622 (1.1-2.0cm)

Note: When performing excisions of small pigmented lesions or non-pigmented neoplasms to rule out melanoma, squamous cell carcinoma, basal cell carcinoma, etc., the sole criterion used to define the term "excision" is the presence of subcutis in the biopsy specimen. This criterion may be met with deep shaves and punches. Of course, as with shave techniques, anesthesia must be used to bill for both the 11400 and 11600 series of codes.