Diseases of the Skin and Subcutaneous Tissue
(ICD-10-CM Chapter 12, Codes L00-L99)
Learning Objectives
2. Identify pertinent anatomy and physiology of the skin and subcutaneous tissue
3. Identify diseases of the skin and subcutaneous tissue
4. Assign the correct Z codes and procedure codes related to the skin and subcutaneous tissue
5. Identify common treatments, medications, laboratory values, and diagnostic tests
6. Explain the importance of documentation in relation to MS-DRGs for reimbursement
Abbreviations/Acronyms
CEA cultured epidermal autograft
FTSG full-thickness skin graft
ICD-9-CM International Classification of Diseases, 9th Revision, Clinical Modification
ICD-10-CM International Classification of Diseases, 10th Revision, Clinical Modification
ICD-10-PCS International Classification of Diseases, 10 th Revision, Procedure Coding System
MS-DRG Medicare Severity diagnosis-related group
STSG split-thickness skin graft
TEN toxic epidermal neurolysis
ICD-10-CM Official Guidelines for Coding and Reporting
Please refer to the companion Evolve website for the most current guidelines.
12. Chapter 12: Diseases of Skin and Subcutaneous Tissue (L00-L99)
1) Pressure ulcer stages
Codes from category L89, Pressure ulcer, are combination codes that identify the site of the pressure ulcer as well as the stage of the ulcer.
The ICD-10-CM classifies pressure ulcer stages based on severity, which is designated by stages 1-4, unspecified stage and unstageable.
Assign as many codes from category L89 as needed to identify all the pressure ulcers the patient has, if applicable.
2) Unstageable pressure ulcers
Assignment of the code for unstageable pressure ulcer (L89.–0) should be based on the clinical documentation. These codes are used for pressure ulcers whose stage cannot be clinically determined (e.g., the ulcer is covered by eschar or has been treated with a skin or muscle graft) and pressure ulcers that are documented as deep tissue injury but not documented as due to trauma. This code should not be confused with the codes for unspecified stage (L89.–9). When there is no documentation regarding the stage of the pressure ulcer, assign the appropriate code for unspecified stage (L89.–9).
3) Documented pressure ulcer stage
Assignment of the pressure ulcer stage code should be guided by clinical documentation of the stage or documentation of the terms found in the Alphabetic Index. For clinical terms describing the stage that are not found in the Alphabetic Index, and there is no documentation of the stage, the provider should be queried.
4) Patients admitted with pressure ulcers documented as healed
No code is assigned if the documentation states that the pressure ulcer is completely healed.
5) Patients admitted with pressure ulcers documented as healing
Pressure ulcers described as healing should be assigned the appropriate pressure ulcer stage code based on the documentation in the medical record. If the documentation does not provide information about the stage of the healing pressure ulcer, assign the appropriate code for unspecified stage.
If the documentation is unclear as to whether the patient has a current (new) pressure ulcer or if the patient is being treated for a healing pressure ulcer, query the provider.
6) Patient admitted with pressure ulcer evolving into another stage during the admission
If a patient is admitted with a pressure ulcer at one stage and it progresses to a higher stage, assign the code for the highest stage reported for that site.
Apply the General Coding Guidelines as found in Chapter 5 and the Procedural Coding Guidelines as found in Chapters 6 and 7.
Anatomy and Physiology
The skin and its accessory organs constitute the integumentary system (Figure 18-1), whose functions include protection, temperature regulation, sensory reception, and vitamin D synthesis.
The skin is composed of 3 layers: epidermis, dermis, and subcutaneous layers. The outer layer of the skin, or the epidermis, serves as a protective barrier and prevents the entrance of disease-causing organisms. The dermis, or middle layer, is composed of fibrous connective tissues that make it strong and elastic. This middle layer contains blood vessels, nerve fibers, sebaceous glands, and some hair follicles. The subcutaneous layer contains fat, sweat glands, and additional hair follicles.
The integumentary system also has accessory organs; these include hair, glands, and nails. Three types of glands are located in the skin: sweat glands, sebaceous glands, and mammary glands. The sweat glands assist in temperature regulation, and the sebaceous glands secrete an oily substance, sebum, which lubricates the hair and skin.
Disease Conditions
Diseases of the Skin and Subcutaneous Tissue (L00-L99), Chapter 12 in the ICD-10-CM code book, are divided into the following categories:
| CATEGORY | SECTION TITLES |
| L00-L08 | Infections of the skin and subcutaneous tissue |
| L10-L14 | Bullous disorders |
| L20-L30 | Dermatitis and eczema |
| L40-L45 | Papulosquamous disorders |
| L49-L54 | Urticaria and erythema |
| L55-L59 | Radiation-related disorders of the skin and subcutaneous tissue |
| L60-L75 | Disorders of skin appendages |
| L76 | Intraoperative and postprocedural complications of skin and subcutaneous tissue |
| L80-L99 | Other disorders of the skin and subcutaneous tissue |
Infections of the Skin and Subcutaneous Tissue (L00-L08)
It is important to note that this section has an Instructional note that advises the user to assign an additional code (B95-B97) to identify the infectious agent if known.
Carbuncle and Furuncle
Another name for a furuncle is a boil, and a cluster of boils is known as a carbuncle (Figure 18-2). The organism that is responsible for a boil is Staphylococcus. This organism enters the body through a hair follicle. An additional code is required to identify the organism responsible.
Cellulitis/Abscess of the Skin
Cellulitis is an acute inflammation of tissue that is characterized by swelling, redness, and tenderness that are most often caused by a bacterial infection. An abscess is a localized collection of pus that causes swelling. Cellulitis is generally treated with antibiotics; an abscess may be treated with antibiotics and also may require incision and drainage.
As is noted in these code categories, acute lymphangitis is included and is NOT coded separately in a patient with cellulitis or abscess. An additional code is used to identify the organism causing the cellulitis, when documented. In ICD-10-CM, if a patient has an abscess and cellulitis, two codes are required.
Cellulitis associated with a superficial injury, burn, or frostbite requires the use of two codes: one code for the injury/burn/frostbite and one code for the cellulitis. The sequence of these codes is dependent on the focus of treatment. For superficial injuries with cellulitis, it is likely that treatment will be focused on the cellulitis.
Cellulitis associated with a traumatic open wound requires the use of two codes: one code for the open wound, complicated, and one code for the cellulitis. The sequence of these codes is dependent on the focus of treatment. If the focus of treatment is the open wound, the code for the wound is sequenced first, followed by the code for cellulitis. If, on the other hand, the focus of the treatment is the cellulitis and the wound is trivial, or if the wound was treated on a separate occasion, the cellulitis would be sequenced first.
Gangrenous cellulitis is assigned only the code for gangrene—NOT a code for cellulitis. Cellulitis associated with a skin ulcer requires the use of two codes: one for the ulcer and one for the cellulitis. The sequence of codes is dependent on the focus of treatment.
Cellulitis occurring in areas other than the skin is coded to the chapter that is most appropriate. The coder will find direction in the Alphabetic Index.
Exercise 18-1
Assign codes to the following conditions.
| 1. Cellulitis of the face | _______________ |
| 2. Cellulitis with lymphangitis of the breast. Staphylococcus aureus infection | _______________ |
| 3. Cellulitis of the left foot due to patient stepping on a nail with open puncture wound of the foot | _______________ |
| 4. Gangrenous cellulitis of toe | _______________ |
| 5. Neck abscess | _______________ |
| 6. Cellulitis, rectum | _______________ |
Bullous Disorders (L10-L14)
Pemphigus
Pemphigus is a rare autoimmune disorder that causes blistering of the skin and mucous membranes, such as the mouth, eyes, throat, and genitals. In people with this disorder, their immune systems attack cells of the epidermis or mucous membranes. This attack causes the formation of blisters that do not heal and can cover large areas of skin. This disorder is not contagious and may have a genetic predisposition. This disease often affects people of Mediterranean descent, and there is a particular form that is found in the rainforests of Brazil. Although this disorder can occur at any age, the most common onset is in middle age or older. There is a similar but different disorder called pemphigoid that causes blistering in areas below the dermis.
There are several different types of pemphigus:
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