Does ICD-10-CM Presume Cellulitis is a Skin Complication of Diabetes?

In the ICD-10-CM Alphabetic Index under the main term, Diabetes and the subterm “with” there is an entry for skin complications NEC. This raises questions regarding coding of cellulitis in patients that also have a diagnosis of diabetes. Based on the “with” convention in ICD-10-CM do these two conditions have a presumed causal relationship?

What Does the ICD-10-CM “With” Convention Say?

ICD-10-CM Convention I.A.15 states:

“With”

The word “with” or “in” should be interpreted to mean “associated with” or “due to” when it appears in a code title, the Alphabetic Index (either under a main term or subterm), or an instructional note in the Tabular List. The classification presumes a causal relationship between the two conditions linked by these terms in the Alphabetic Index or Tabular List. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated or when another guideline exists that specifically requires a documented linkage between two conditions (e.g., sepsis guideline for “acute organ dysfunction that is not clearly associated with the sepsis”). For conditions not specifically linked by these relational terms in the classification or when a guideline requires that a linkage between two conditions be explicitly documented, provider documentation must link the conditions in order to code them as related. The word “with” in the Alphabetic Index is sequenced immediately following the main term or subterm, not in alphabetical order.

Based on the entries in the Alphabetic Index and this definition it seems plausible that cellulitis in the presence of diabetes might have a presumed link. Fortunately, Coding Clinic has provided clarification regarding presuming a causal relationship between diabetes and diagnoses not specifically included as entries under the “with” subterm.

Clarification From AHA Coding Clinic

The direction in AHA Coding Clinic 4th Qtr. 2017, page 100 clarifies that there is NO presumed causal relationship between diabetes and cellulitis as a skin complication of diabetes because there is no specific index entry for “diabetes with cellulitis”. Coding Clinic goes on to explain that the “with” guideline does not apply to “not elsewhere classified (NEC)" index entries that cover broad categories of conditions. If this were the case, then any skin issue would be considered a diabetic complication when patients have both the condition and diabetes. An example would be a patient with diabetes and acne. It’s most likely the acne is not a complication of the diabetes but rather a manifestation of puberty or another skin disorder. This advice applies to other conditions, such as arthropathy, that are indexed under the subterm “with” and have a designation of NEC. In light of the clarification in Coding Clinic, the provider needs to document the cellulitis as a skin complication of diabetes for it to be coded as such.

Examples:

• A patient presents with cellulitis of the right foot and toes. The patient also has a history of type 2 diabetes and is currently using insulin for control. There is no link made by the physician indicating the cellulitis is a complication of or related to the diagnosis of diabetes.
  
  In this case, the coder would not assign a code for skin complication of diabetes. Before this type of code can be reported, the physician would need to be queried for clarification of the link between the two diagnoses.
  
  
• A patient with type 2 diabetes has a documented diagnosis of ulcer of the right foot and cellulitis of the right foot and toes.
  
  In this case, a causal relationship can be presumed between the foot ulcer and the diabetes, but the provider should be queried to determine if the cellulitis is also linked to the patient’s diabetes. 
  
  
• A diabetic patient presents with a laceration with accompanying cellulitis. The physician documents laceration, left lower leg with development of cellulitis due to diabetes. 
  
  In this case, the provider has linked the diabetes and the cellulitis, so a code for diabetic skin complication should be assigned.

References:

• AHA Coding Clinic® for ICD-10-CM and ICD-10-PCS, Fourth Quarter 2017 Page: 100-101
• ICD-10-CM Official Guidelines for Coding and Reporting I.A.15

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The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.