Procedures on skin can be some of the most difficult to code because of the many categories of lesions, location of lesions, number of lesions, diameter of lesions, incomplete documentation, and the terminology used by physicians. Here are some guidelines for correct coding of skin lesions:
Lesions are categorized as skin tags, warts, neoplasms, or masses/lumps (cyst, tumor). First consult the ICD-10-CM Index for the term documented. For example, cysts are categorized to the tissue in which they are found. If the documentation shows the cyst or lesion was removed from skin tissue, find the term Cyst, followed by the sub term skin, followed by the type of cyst.
Neoplasms can be either malignant, benign, uncertain behavior, or unspecified behavior. Malignant lesions can be primary, the first site of malignancy; secondary, site where primary malignancy has metastasized or “spread”; and carcinoma in situ, an early form of cancer defined by the absence of invasion of tumor cells into the surrounding tissue.
Benign lesions are not malignant and do not metastasize or “spread” to other parts of the body. Benign lesions look similar to the tissue where the lesion originated and grow slowly. Though benign lesions are not cancerous, they may cause problems because of their location and often there are multiple benign lesions which can cause adverse effects on the body.
Lesions of uncertain behavior are categorized as uncertain when the lesion has not been identified as malignant or benign. The physician needs to document uncertain behavior in order for this category to be used. Usually, uncertain behavior is documented on preoperative diagnoses and documentation prior to surgical removal and submission to pathology. The pathologist will then clarify whether the lesion is benign or malignant.
Lesions of unspecified behavior are lesions where there is absence of documentation of benign, malignant, or uncertain. This is the “catch all” category and should be used as little as possible.
Location of skin lesions
Skin tissue has three main layers which are divided into sub layers. The location of the skin lesion in the skin layers will determine the code category that is used.
The epidermis is the outermost main layer of skin. This layer includes the stratum corneum (horny sub layer), followed by the keratinocytes (squamous cells sub layer), and finally the basal sub layer. The horny sub layer is continuously shed and prevents foreign substances and loss of fluid from the body. The squamous cells sub layer lies just beneath the horny sub layer. The basal sub layer is the deepest sub layer of the epidermis. Throughout the epidermis are melanocytes, specialized cells which produce melanin (skin pigment).
The second main layer of skin tissue is the dermis, also called the middle layer. Blood vessels, lymph vessels, hair follicles, sweat glands, collagen bundles, fibroblasts, and nerves are located in this layer. The dermis is held together by collagen. The dermis is flexible and strong. Because the nerves are located in this layer, this is where pain and touch receptors are located.
The third main layer of skin tissue is the subcutaneous layer. The subcutaneous layer is also known as subcutis, meaning under the skin. This is the deepest layer of skin made of collagen and fat cells. This layer helps preserve body heat and protects against injury by acting as a barrier.
Common terminology for skin lesions
Physicians may use a variety of terminology to describe lesions of the skin, even within the same document. The lesion may be described as a cyst, sebaceous cyst, tumor, subcutaneous mass, soft tissue lesion, skin tag, and wart, etc.
When coding skin lesions and their removal, try not to get caught up in the terminology and stick to the facts. The ICD-10-CM table of neoplasm has clear instructions and guidance on coding skin lesions. “Where such descriptors [malignant primary, malignant secondary, carcinoma in situ, benign, uncertain behavior, or unspecified behavior] are not present, the remainder of the Index should be consulted… ” [CMS.org ICD-10-CM]
The coder should always first consult the Index for the terminology used by either the physician or the pathologist. The Index will lead the coder to the correct section of the ICD-10-CM Tabular List.
Important Facts the Coder Needs to Know
- Where was the lesion located? Skin, bone, muscle…
- Size of lesion in centimeters?
- Type of wound closure? Simple, intermediate, complex…
- Length of closure in centimeters?
- What was actually done to the lesion? Biopsy, removal, shaving, excision…
Code selection is based on a number of factors including the answers to the above questions. By first consulting ICD-10-CM Index and then Tabular List, this will help guide your procedure code selection. If a benign tumor is excised from the soft tissue in the left arm, the procedure code will reflect excision of lesion from soft tissue or connective tissue, upper left extremity. It would be inappropriate to select codes from the skin category for either the diagnosis or procedure codes as this particular tumor was in the soft tissue.
Common Procedures for Skin Lesions
Some of the most common procedures for skin lesions include biopsy, shaving, excision, destruction (cryotherapy and electrosurgical), cutting or paring, debridement, excisional debridement, and curettage. Depending on whether the procedure is performed as an inpatient (ICD-10-PCS) or outpatient (CPT®) will guide your procedure code selection.
ICD-10-PCS Inpatient Procedures for Skin Lesions
Excision is defined in ICD-10-PCS as cutting out or off without replacement some of a body part with the use of a sharp instrument including scalpel, wire, scissors, and bone saw, electrocautery, etc. The qualifier DIAGNOSTIC is used to identify excisions that are biopsies in ICD-10-CM.
Destruction is defined as eradicating without replacement some/all of a body part so that the body part is no longer there. Destruction is accomplished with the use of direct use of energy, force, or a destructive agent. None of the body part is taken out and therefore there will most likely not be a pathology report on lesions removed by this method.
Extraction is defined as pulling or stripping out or off all or a portion of a body part (by use of force either manual or suction. The qualifier DIAGNOSTIC is used to identify extraction procedures that are biopsies. Debridement and curettage would fall under this category.
Outpatient Procedures for Skin Lesions
Definitions for CPT® procedures are included in the AMA CPT® Code Book. Procedures used to treat skin lesions include biopsy, shaving, excision, destruction (cryotherapy and electrosurgical), cutting or paring, excisional and non-excisional debridement, and curettage.
Biopsy is the removal a sample of the lesion and submitted to pathology. The pathologist will evaluate the lesion under the microscope and help guide the care required for treatment of the lesion by identifying the type of lesion in the sample. At times, the entire lesion may be removed as a biopsy sample.
Biopsies that are documented as shave biopsies are either coded to biopsy codes or shave excision codes. There is not a CPT® code that directly correlates with shave biopsy. Review the documentation carefully. Match the documentation to the CPT® code description.
Excision is the removal of the lesion completely with margins and submitted to pathology.
Destruction employs heat, freezing, chemicals, lasers and/or curettage to destroy the lesion in place. Destruction does not usually leave any material as specimen to be submitted to pathology.
Cutting or paring involves the use of a blade, curette, or similar sharp instrument. Paring and shaving involve removing the lesion just to the level of the skin, similar to scraping.
CPT® code selection is based on anatomic location (arms, legs, trunk, face, nose, etc.) and size of the lesion in centimeters. The physician must document the size of the lesion either in width and length or diameter. Be careful not to confuse the wound closure length with the lesion size. These are often very different measurements.
Lesion Excision and Margins
For outpatient procedure coding, it is important to include the margin of the lesion in the size of the excision code. CPT® Code Books instruct the coder to select codes based on the greatest clinical diameter of the lesion plus the margin required for complete excision. Code selection is based on the sum of the size of the lesion and its margins.
3.4 cm lesion of the upper back excised
1.5 cm surrounding margin
Total sum of excision 4.9 cm.
Coding Excision of Multiple Lesions
CPT® Code Books have detailed instructions on the code selection for removal of multiple lesions in the same operative session.
First, the coder must report separately each lesion excised. Select the code based on the diameter of the lesion plus the narrowest margin.
Second, closure of the defects created by the excisions is reported when the closure is intermediate or complex. Simple closure is included in the excision code and is defined as involving primarily epidermis and dermis or subcutaneous tissues. Simple closure requires a simple one layer closure and includes the local anesthesia and chemical or electrocauterization of wounds not closed by suture.
Intermediate closure is defined as layered closure. Intermediate closure also includes simple closure of heavily contaminated wounds that require extensive cleaning.
Complex closure is defined as requiring more than layered closure including extensive undermining of the wound, retention sutures, and skin grafting procedures.
CPT® Code Book instructs the coder “when multiple wounds are repaired, add together the lengths of all those in the same classification [simple, intermediate, or complex] and from all anatomic sites that are grouped together into the same code descriptor [i.e., closure of wound defects of multiple upper extremity lesion excisions would be grouped together; closure of wound defects of the back would be grouped together].
A) 2.3 cm benign lesion of upper right arm with 1 cm margins. Intermediate closure.
B) 2.5 cm benign lesion of upper left arm with 1 cm margins. Intermediate closure.
C) 1.2 cm benign lesion of upper right arm with 1 cm margins. Simple closure.
D) 2.5 cm benign lesion upper left thigh with 1 cm margins. Intermediate closure.
E) 3.2 cm benign lesion of upper left thigh with 1 cm margins. Intermediate closure.
Benign lesion right forearm
Benign lesion left forearm
Benign lesion left thigh
Excision benign lesion trunk, arms, or legs 3.3 cm [lesion A]
Excision benign lesion trunk, arms, or legs 3.5 cm [lesion B]
Excision benign lesion trunk, arms, or legs 2.2 cm [lesion C]
Excision benign lesion trunk, arms, or legs 3.5 cm [lesion D]
Excision benign lesion trunk, arms, or legs 4.2 cm [lesion E]
Intermediate repair wounds of scalp, axillae, trunk, and/or extremities (excluding hands/feet) 3.3 cm [lesion A] + 3.5 cm [lesion B] + 3.5 cm [lesion D] + 4.2 cm [lesion E] = 14.5 cm
Simple repair wounds of scalp, axillae, trunk, and/or extremities (excluding hands/feet) 2.2 cm [lesion C] = 2.2 cm
Avoid Costly Coding Mistakes
By following these rules for correct coding of skin lesions and their removal, the coder can help avoid costly coding mistakes. Many coders feel comfortable coding directly from the operative report. However, when there are multiple procedures or lesions removed, it is best to sort out the facts before attempting to select codes. Follow these steps in order to avoid coding mistakes:
- Review all of the documentation on the medical record.
- Note lesion location(s)
- Lesion size including margin
- Do not use the pathology report for this information. The process of preserving the specimen alters the size of the lesion.
- Type of lesion(s)
- Benign neoplasm
- Malignant neoplasm
- Uncertain neoplasm
- Unspecified neoplasm
- Exact procedure for each lesion
- Closure type and length for each wound
- Select ICD-10-CM code(s) to appropriately report the lesion(s). Multiple lesions of the same anatomic site are coded only once for the ICD-10-CM diagnosis code.
- Review the operative note carefully to determine lesion size(s) and type(s) of wound closure.
- For inpatient encounters, select the ICD-10-PCS procedure code(s) appropriate to report the procedure(s). **is graft included??
- For outpatient encounters, select the CPT® procedure code(s) appropriate to report the diameter plus margin for the lesion(s).
- For outpatient encounters, select the CPT® procedure code(s) appropriate to report the closure of the wound defect for the lesion(s). Multiple wound closures in the same anatomic site are coded together by adding the sum of the lengths of the closure(s) of the same type [intermediate or complex].
- Add modifiers to CPT® procedure codes are required. See Modifier 59 rules.
By carefully reviewing medical record documentation for category of lesion, lesion location(s), and the terminology used by physicians and pathologists, the coder can appropriately code and expect reimbursement for inpatient and outpatient procedures on skin lesions. Using these guidelines, the coder can avoid costly coding mistakes and need for future rebills.