Procedure Practice 03/15/98 - Coding Recommendations

Feature Article 03/15/98

The Skin

Anatomy - Function - Primary Infections - Inflammatory Diseases Neoplasms - Coding Scenarios

The skin is the largest organ of the body, serving as a protective interface with the environment. Its considerable surface area and constant environmental exposure contribute to the variety of disease conditions that affect the skin. This month we review the skin’s basic anatomy and describe some of the diseases that coders frequently see documented in medical records. Then, because CPT-4 coding of skin procedures is particularly problematic for many coders, several procedures are presented for analysis and code assignment.

Anatomy

Epidermis - The epidermis forms the external surface of the skin and is mainly composed of keratinocytes which differentiate to form 4 layers: the stratum basale (basal layer), stratum spinosum (spinous layer), stratum granulosum (granular layer), and the stratum corneum (surface layer). Keratinocytes are cells that produce several types of keratin proteins. Keratin proteins strengthen and stiffen the skin and are found in the epidermis, hair, and nails. Keratinocytes produce increasingly greater quantities of keratins as they migrate from the basal layer to the surface layer of the epidermis, a journey that normally takes 28 days.

In addition to keratinocytes, the epidermis contains melanocytes, Langerhans cells, and Merkel cells. Melanocytes are the pigment cells of the epidermis. They produce the dark pigment melanin, which is partially protective against ultraviolet radiation. Langerhans cells contain antigens and are involved in immunological responses in the skin. Merkel cells are found in the basal layer of epidermis and are believed to function as mechanoreceptors.

Dermis - The dermis is separated from the epidermis by a basement membrane. The dermis is divided into 2 layers, the papillary dermis and the reticular dermis. Cellular components of the dermis include fibroblasts, histiocytes, endothelial cells, perivascular macrophages, mast cells, smooth muscle, and the cells of peripheral nerves and their end-organ receptors. The dermis also contains a large amount of collagen, a fibrous tissue which gives skin its tensile strength and elasticity.

Hypodermis - This layer of skin contains adipose tissue and attaches the dermis to its underlying tissues.   

Adnexal Structures - Adnexal components are of epidermal origin and extend into the dermis. They include hair follicles, sweat glands, sebaceous glands, and nails.

Function

• Protection - The skin is a barrier against such things as water loss/entry, chemicals, bacteria and fungi, and minor trauma. The protective function is served by the lipids and proteins of the stratum corneum which is continually sloughed off and regenerated. Beneath the dermis is the subcutaneous fat, a thermal barrier and mechanical cushion to protect internal organs.
     
• Sensation - Elaborate neural receptors and small nerve endings govern the sensations of touch, pressure, temperature, and pain.
     
• Thermoregulation - Accomplished via the sweat glands.
     
• Immunological Defense - Provided by the Langerhans cells.
     
• Vitamin-D Synthesis - Activated in response to sun exposure.
     
• Pigmentation - Supplied by melanocytes protects against ultraviolet radiation.
     
• Wound healing.

Dermatopathology
  

Primary Skin Infections

Impetigo - Impetigo is a common, superficial, highly contagious infection which may affect healthy children or adults in poor general health. Outbreaks occur frequently in day-care centers, schools, and other group settings. Impetigo is caused by Staph aureus or beta-hemolytic strep. Lesions occur on exposed skin surfaces, particularly the hands and face. If a pre-existing skin condition is complicated by a secondary bacterial infection, it is said to be "impetiginized."

Verruca Vulgaris - Verrucae (warts) are common lesions of the skin or mucous membranes caused by a human papilloma virus (HPV). Verruca vulgaris is the most common type of wart; other types include verruca plana (flat wart), verruca plantaris (on the sole of the foot), and condyloma acuminatum (venereal wart). Verrucae vulgaris may occur anywhere on the body, but are most often found on the hands. They are grayish-white or tan in color with a rough, convex surface.

Herpes Simplex Virus (HSV) - The two sites of HSV infection are the orofacial and genital regions. The viruses start as a primary infection with painful vesicles located along the lips, face, oral mucosa or genitalia, and then travel along a peripheral nerve to reside in the sensory nerve ganglion where they remain dormant until recurrence.

Herpes Zoster (Shingles): Shingles represents a reactivation of a latent varicella (chicken pox) virus. Adults with shingles can transmit varicella to children, but children with shingles cannot transmit varicella to adults.

Dermatophytic fungi: Many superficial fungal infections affect the outer layer of the epidermis. Various forms of tinea (ringworm) are some of the most common of these fungal skin conditions. The fungus responsible for tinea colonizes in the keratin of the hair, nails, and outermost layer of epidermis. The names of the various forms of tinea infection are derived from the primary infection site.

Tinea Capitis - This form, which affects the skin on the scalp, usually occurs in young children. The site of infection usually loses hair and becomes red and crusty. If left untreated, the infection may become painful and cause deep inflammation and pustule formation.

Tinea Corporis - This is a common infection of the general body surface. Lesions are well-defined with a raised, red, scaly border.

Tinea Cruris - This infection is located in the inguinal area and often affects over-weight people, particularly during hot, humid weather. The skin is red, scaly, and itchy.

Tinea Pedis (athlete’s foot) - This infection of the skin of the feet affects 30-40% of people at some time during their lives. There is diffuse erythema and scaling with pruritis, often starting in the spaces between the toes and extending to the sole of the foot. Onychomycosis is the term applied to the infection when it involves the nails.
   

Inflammatory Diseases of the Skin

   
Acute Inflammatory Dermatoses

Urticaria (hives) - The term "hives" refers to a common allergic reaction of skin to various environmental agents such as foods, drugs, insect venom, pollens, detergents, etc. Lesions on the skin may appear as small itchy papules or large areas of edematous plaques. Most lesions develop and fade within 24 hours.

Spongiotic Dermatitis (eczema) - Eczema is a collective term applied to several different conditions, all sharing the common feature of edema of the epidermis. Some of the conditions that belong to this family of skin afflictions are:

Allergic contact dermatitis: Common agents causing contact dermatitis include the rhus toxin present in poison ivy and poison oak, hair dyes, nickel and rubber compounds, and epoxy resins.

Irritant contact dermatitis: This form of dermatitis is a non-allergic skin reaction due to damage by a chemical or physical agent. People who wash their hands frequently often suffer from this type of dermatitis. Dryness, cracks and fissures in the skin, and erythema are common clinical signs of this condition.

Atopic dermatitis: Atopic dermatitis is a chronic relapsing skin disorder of unknown cause with skin dryness, erythema, and pruritis (itching) occurring in people with a personal or family history of "atopy" (multiple allergies, asthma, hay fever, allergic rhinitis, conjunctivitis, or atopic dermatitis). Most people develop atopic dermatitis symptoms in the first 5 years of life.

Erythema Multiforme - This condition is due to hypersensitivity to various antigens. Unlike contact allergies, the reaction causes degeneration and necrosis of epithelial cells. The 3 forms of the disease are:

Erythema multiforme minor is a self-limited disorder characterized by a slowly migrating erythema that tends to be symmetric on both sides of the body, involving the extremities and sometimes the oral mucosa.

Erythema multiforme major, also called Stevens-Johnson syndrome, is a catastrophic illness often caused by sulfonamide antibiotics. There is a sudden onset of skin and mucous membrane lesions, and the lips often develop hemorrhagic crusts. The most severe cases involve the esophagus or bronchial tree, making eating and breathing painful and difficult. Mortality is 30-40%.

Toxic epidermal necrolysis (TEN) is the most extreme form of the disease, usually caused by sulfa drugs, penicillins, or anticonvulsants. The epidermis becomes totally necrotic, producing eroded skin lesions which resemble 3rd degree burns. Mortality is as high as 66% and is usually due to sepsis.
   

Chronic Inflammatory Dermatoses

Psoriasis - Psoriasis is a common chronic inflammatory disease which occurs in 1-3% of the population. An exact etiology is not known, although about 30% of patients with the disease have a family history of psoriasis. Psoriasis most commonly affects the elbows, knees, scalp, lumbosacral area, and intergluteal cleft. Lesions are itchy, red plaques covered with a silvery-white scale. In 30% of all cases, this disorder also affects the nails, causing discoloration and sometimes separation of the nail plate from the bed (onycholysis). Approximately 7% of psoriasis patients suffer from associated "psoriatic arthritis," which may be mild or can produce joint destruction similar to rheumatoid arthritis.

Lichen Planus - Lichen planus is another common chronic disorder with an unknown etiology. Lesions are pruritic, purple plaques or papules located on the extremities and buccal mucosa. Lesions last months or years, heal, and leave temporary post-inflammatory hyperpigmented spots on the skin surface.

Discoid Lupus Erythematosus - This localized, cutaneous form of lupus erythematosus (LE) has no associated systemic symptoms. A patient with discoid lupus erythematosus usually does not go on to develop systemic LE. The skin lesions are sharply defined, round (discoid), red, scaling plaques. Discoid lupus erythematosus, like systemic LE, is an autoimmune collagen disease with an unclear etiology.

Acne Vulgaris (common acne) - Acne is the result of the interaction of 3 key factors: overactivity of the sebaceous glands, plugging of the sebaceous duct, and bacterial activity. Sebaceous glands are most prominent on the face, neck, upper chest, and upper back. They are controlled by androgens and do not secrete sebum until puberty. In acne, sebum secretion is increased. Free fatty acids, which are the breakdown product of sebum, act as irritants which promote the pathogenesis of acne. In acne, the keratin lining the sebaceous duct adheres to the sebum and bacteria in the duct, effectively blocking it. The blockage of the duct by this keratin plug is called a comedone. Bacteria colonize the blocked duct and contribute to the inflammatory appearance of this disease.
   

Skin Neoplasms

Each component of skin can give rise to benign and malignant neoplasms. Keratinocytes can develop into squamous cell and basal cell carcinomas. Melanocytes can develop into nevi (benign neoplasms) and malignant melanomas. Blood vessels, smooth muscle cells, and nerve components can also be sources of tumors.
   

Keratinocyte Derived Neoplasms

Basal Cell Carcinoma (BCC) - Basal cell carcinomas are the most common malignant neoplasm in Caucasians. BCCs usually occur on sun-damaged skin, particularly in fair skinned people with red hair and blue eyes. BCCs are very slow growing, painless tumors which are locally invasive, but rarely metastasize. The tumors present particular surgical and cosmetic repair problems when they occur near the eyes, nose, temples, or ears.

Squamous Cell Carcinoma (SCC) - SCCs are the most common tumor arising from the sun-damaged skin of elderly people. They differ in structure from BCCs and have the potential to metastasize to regional lymph nodes. The risk of metastasis is directly related to the depth of invasion into the dermis or subcutis.

Actinic Keratosis - Actinic keratoses are premalignant lesions caused by sun damage and usually occur on the chronically exposed areas of the skin such as the face, ears, and dorsal surface of the hands. These lesions may evolve into squamous cell carcinomas if not removed.

Keratoacanthoma - These benign neoplasms are cup-shaped and filled with keratin. They tend to occur on sun-damaged skin. They usually grow rapidly and sometimes spontaneously regress.

Seborrheic Keratosis - These lesions are very common benign epidermal tumors often seen in elderly patients. They are wart-like in appearance, often appearing to be "stuck on" to the skin’s surface.
  

Melanocyte Drived Neoplasms

Nevi (moles) - Melanocytic nevi are pigmented, benign neoplasms composed of modified melanocytes. They may be congenital or acquired lesions. The average person with no nevi present at birth will acquire about 24 nevi by age 24. Benign acquired nevi group into three categories: junctional, intradermal, and compound nevi.

Dysplastic Nevus Syndrome - Dysplastic nevi generally develop in early adolescence or adulthood and are present in great numbers. They are generally larger than other more commonly occurring nevi with uneven surfaces or borders. They occur on the back, buttocks, and skin of the groin. Patients with dysplastic nevi syndrome are at increased risk for malignant melanoma, which can arise within these nevi.

Malignant Melanoma - Malignant melanoma is a very aggressive neoplasm which often arises on sun-exposed skin. On rare occasions it occurs in the retina or mucous membranes. It is characterized by an irregularly shaped and irregularly pigmented macule or nodule. Prognosis for melanoma is directly related to tumor depth of invasion. As the measured depth of invasion increases, so does the probability of metastases. Melanomas metastasize to regional lymph nodes via the lymphatics. They metastasize through the blood vessels to the lung and brain.
   

Other Skin Neoplasms

Mycosis Fungoides - This is a cutaneous T-cell lymphoma which first presents in the skin. The lesions may remain localized for many years and then evolve into systemic lymphoma. Mycosis fungoides lesions are scaly, red, raised nodules most often distributed along the upper thighs and buttocks.

Kaposi’s Sarcoma - Kaposi’s sarcoma used to be a rare tumor seen most often in elderly males of Mediterranean descent. Today, Kaposi’s lesions are primarily seen in AIDS patients. The lesions are reddish-purple patches and nodules, and may appear anywhere on the skin. The course of the disease may be aggressive and involve the lungs, lymph nodes, and mucosa of the gastrointestinal tract.

Coding Scenarios

Because CPT-4 coding of skin procedures is often more difficult than ICD-9 coding, even for experienced coders, this month we are presenting several case synopses in addition to one full length operative report for coding practice. For each case, assign the appropriate ICD-9-CM diagnosis and procedure codes as well as the CPT-4 procedure code(s). Then review our case analyses and suggested codes to find out how well you did.
   

Case Synopses

1. A 41-year-old woman presents with a malignant melanoma of the lower back and undergoes Mohs surgery for excision of the lesion with a total of 3 specimens submitted.
     
2. A 68-year-old man has a 1.3 x .7 x 2.2 cm. lesion excised from his lower leg. The wound is closed in a single layer with 4-0 Vicryl. The pathology report shows a 1.2 x .6 x 1.9 cm. pigmented nevus.
      
3. An 57-year-old man, status post ventral hernia repair, has incision and drainage of an infected postoperative abscess in the doctor’s office. The wound is closed after placement of a latex drain. The patient is placed on p.o. antibiotics. The culture grows staph aureus.
      

Discussion and Code Assignments

1. The malignant melanoma of the back is coded 172.5, Malignant melanoma of skin, trunk, except scrotum. Note that melanoma has its own entry in the Index to Diseases and is not found in the Index’s Table of Neoplasms, except as a cross-referenced entry.
     
   Mohs micrographic surgery is a specialized technique for removal of skin cancer. The surgeon places a chemical agent on the lesion prior to excision. This chemical acts as a tissue fixative. The lesion is excised via serial tangential cuts, allowing the surgeon to examine wound margins and extent of tumor invasion during surgery. The correct ICD-9-CM procedure code is 86.24, Chemosurgery of skin, chemical peel of skin. Provided that the same physician performs both the surgery and the pathological specimen analysis, as usually is the case, the correct code assignment is 17304, Chemosurgery (Mohs micrographic technique), including removal of all gross tumor, surgical excision of tissue specimens, mapping, color coding of specimens, microscopic examination of specimens by the surgeon, and complete histopathologic preparation; first stage, fresh tissue technique, up to 5 specimens.
      
2. The pathology report is helpful to the coder because it reveals that the lesion is benign. The correct diagnosis code is 216.7, Benign neoplasm of skin of lower limb, including hip. The ICD-9-CM procedure code is 86.3, Other local excision or destruction of lesion or tissue of skin and subcutaneous tissue. This code includes many methods of destruction: cautery, cryosurgery, fulguration, laser destruction, and excision with Z-plasty repair. The correct CPT-4 code is 11403, Excision, benign lesion, except skin tag (unless listed elsewhere), trunk, arms, or legs; lesion diameter 2.1 to 3.0 cm.
      
   Always use the size of the lesion as stated in the operative report to select the correct CPT-4 code. Pathology reports give the size of the specimen, which may or may not be the same as the lesion size. Specimens may be larger or, depending upon the fixative used for processing, may shrink and, therefore, be reported by the pathologist as smaller than the actual lesion.
      
3. Assign 998.59, Other postoperative infection, for the infected abscess. An additional code, 041.11, Bacterial infection in conditions classified elsewhere, staphylococcus aureus, is assigned to identify the infecting organism. Incision and drainage of an abscess is coded to 86.04, Other incision with drainage of skin and subcutaneous tissue.
      
   The correct CPT-4 code is 10180, Incision and drainage, complex, postoperative wound infection. In CPT-4, incision and drainage of an abscess is defined as complex if one of the following conditions exist:

• A drain or packing is placed in the wound.
• Hemorrhage requiring ligation occurs.
• The area of infection is very large.
    

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Also try coding the surgical procedure(s) in the Operative Report on our Procedure Practice page. Compare your code selections with our suggetions on the Coding Recommendations page.

If you have comments or suggestions about our code selections or about any topic on our Coding Edge® pages, please e-mail us at codingedge@lagunamedsys.com.