What are neoplasms of uncertain behavior?

By Raymond Janevicius, MD
05/26/2011 at 2:00PM

Skin lesions are generally considered benign or malignant, but certain lesions are designated as exhibiting "uncertain behavior." This month's column will examine these lesions and how their excisions are coded.

View Table I. and Table II.


The term "neoplasm of uncertain behavior" is a specific pathologic diagnosis. This is a lesion whose behavior cannot be predicted. It's currently benign, but there's a chance that it could undergo malignant transformation over time. The ICD-9 book indicates that these are "certain histo-morphologically well-defined neoplasms, the subsequent behavior of which cannot be predicted from the present appearance."

For example, a nevus sebaceous of Jadassohn is a benign lesion, but there is an approximately 15 percent chance that it could become a basal cell carcinoma. Which of these lesions will degenerate into a malignancy is unknown. Its behavior is "uncertain," hence the term "neoplasm of uncertain behavior."

A single ICD-9 code, 238.2, is used for skin lesions of uncertain behavior, regardless of anatomic location. If the lesion involves the vermilion of the lip, code 235.1 is reported.

Not uncertain diagnosis

A skin lesion which has been excised, but for which no pathology report is yet available, is not a neoplasm of uncertain behavior. While awaiting pathologic verification this is, using ICD-9 terminology, a lesion of "unspecified nature," i.e., 239.2. It should not be reported with code 238.2, neoplasm of uncertain behavior. Once the pathology report is obtained, a specific diagnosis has been determined, and the lesion can be assigned an appropriate ICD-9 code.

Reporting a lesion of unknown diagnosis as a lesion of uncertain behavior is a common coding error. If you are unsure of the diagnosis of a skin lesion prior to excision, wait for the final pathology report to assign a diagnosis. ICD-9 code 238.2 is not appropriate during the "waiting period" for pathology. Waiting for the final diagnosis may mean a delay in submitting your bill, but it's preferable to submit with the correct diagnosis.

Coding excisions of neoplasms

Many of these lesions are excised with margins. Report the excisions of neoplasms of uncertain behavior with the benign lesion excision codes, 114XX. As with all benign lesion excisions, select the code based on the size of the lesion in situ plus the margins of resection. For example, consider an 8 mm dysplastic nevus of the neck, excised with 2 mm margins. The "excised diameter" is 8 mm + 2 mm + 2 mm = 12 mm. Select code 11422, based upon an excised diameter of 12 mm (1.2 cm). Use ICD-9 code 238.2 for the diagnosis of this lesion.

Other examples

Some examples of lesions of uncertain behavior include congenital giant pigmented nevus, dysplastic nevus and nevus sebaceous of Jadassohn. (See Table I and Table II.) Actinic keratoses are also skin lesions of uncertain behavior, but actinic keratoses have a more specific ICD-9 code, 702.0. Do not report actinic keratoses with code 238.2.

In the past, keratoacanthomas were considered lesions of uncertain behavior. The current pathology literature indicates that these are low-grade squamous cell carcinomas. Thus, they are described with the skin malignancy codes, 173.X, and their excisions are reported with the malignant lesion excision codes, 116XX.

- Dr. Janevicius is the ASPS representative to the AMA CPT Advisory Committee.

Code of the Month

A young woman undergoes the excisions of multiple lesions. A 12 mm nevus sebaceous of Jadassohn of the scalp is excised with 5 mm margins. Sub-galeal undermining is necessary to effect closure, which measures 5 cm. A 7 mm dysplastic nevus of the right cheek is excised with 2 mm margins, and a 3 cm layered closure is performed. A 7 mm keratoacanthoma of the temple is excised with 3 mm margins, and a 3 cm layered closure is performed. A 3 mm suspicious lesion of the forehead is excised.


13121 Complex repair scalp, 2.6- 7.5 cm
12053-59 Intermediate repair of face, 5.1-7.5 cm
11642-51 Excision of keratoacanthoma of temple, 1.1-2.0 cm (ICD-9 173.3)
11423-51 Excision of nevus sebaceous of scalp, 1.1-2.0 cm (ICD-9 238.2)
11441-59 Excision of dysplastic nevus of cheek, 0.6-1.0 cm (ICD-9 238.2)
11440-59 Excision of suspicious lesion of forehead, <0.5 cm (ICD-9 239.2)

  • The nevus sebaceous and the dysplastic nevus are neoplasms of uncertain behavior. ICD-9 code 238.2 is used for these lesions.
  • The excisions of the nevus sebaceous and dysplastic nevus are reported with the benign lesion excision codes, based on the excised diameter, not the size of the lesion.
  • The keratoacanthoma is not a lesion of uncertain behavior; it's a low-grade skin malignancy. Report with the malignant lesion CPT and ICD-9 codes.
  • The suspicious lesion does not have a diagnosis at the time of surgery. It's a lesion of "unspecified nature," 239.2. It's not a lesion of uncertain behavior, so ICD-9 code 238.2 is not appropriate here. 
  • Complex and intermediate repairs are reported in addition to the excision codes.