2019 ICD-10-CM Diagnosis Code C4A.9

Merkel cell carcinoma, unspecified

    2016 2017 2018 2019 Billable/Specific Code
  • C4A.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2019 edition of ICD-10-CM C4A.9 became effective on October 1, 2018.
  • This is the American ICD-10-CM version of C4A.9 - other international versions of ICD-10 C4A.9 may differ.
Applicable To
  • Merkel cell carcinoma of unspecified site
  • Merkel cell carcinoma NOS
The following code(s) above C4A.9 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to C4A.9:
  • C00-D49
    2019 ICD-10-CM Range C00-D49

    Neoplasms

    Note
    • Functional activity
    • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
    • Morphology [Histology]
    • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
    • Primary malignant neoplasms overlapping site boundaries
    • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
    • Malignant neoplasm of ectopic tissue
    • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
    Neoplasms
Approximate Synonyms
  • Cancer, merkel tumor
  • Merkel cell carcinoma
Clinical Information
  • A carcinoma arising from merkel cells located in the basal layer of the epidermis and occurring most commonly as a primary neuroendocrine carcinoma of the skin. Merkel cells are tactile cells of neuroectodermal origin and histologically show neurosecretory granules. The skin of the head and neck are a common site of merkel cell carcinoma, occurring generally in elderly patients. (holland et al., cancer medicine, 3d ed, p1245)
  • A rare malignant cutaneous tumor seen in elderly patients. Its usual location is on the head, neck and extremities. The tumor is composed of small round cells with scanty cytoplasm arranged in a trabecular pattern, or in ill-defined nodules or in a diffuse pattern. The tumor cells contain cytoplasmic membrane-bound dense core granules resembling neurosecretory granules.
  • A rare type of cancer that forms on or just beneath the skin, usually in parts of the body that have been exposed to the sun. It is most common in older people and in people with weakened immune systems.
ICD-10-CM C4A.9 is grouped within Diagnostic Related Group(s) (MS-DRG v36.0):
  • 595 Major skin disorders with mcc
  • 596 Major skin disorders without mcc

Convert C4A.9 to ICD-9-CM

Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change

Diagnosis Index entries containing back-references to C4A.9:

ICD-10-CM Codes Adjacent To C4A.9
C4A.59 Merkel cell carcinoma of other part of trunk
C4A.6 Merkel cell carcinoma of upper limb, including shoulder
C4A.60 Merkel cell carcinoma of unspecified upper limb, including shoulder
C4A.61 Merkel cell carcinoma of right upper limb, including shoulder
C4A.62 Merkel cell carcinoma of left upper limb, including shoulder
C4A.7 Merkel cell carcinoma of lower limb, including hip
C4A.70 Merkel cell carcinoma of unspecified lower limb, including hip
C4A.71 Merkel cell carcinoma of right lower limb, including hip
C4A.72 Merkel cell carcinoma of left lower limb, including hip
C4A.8 Merkel cell carcinoma of overlapping sites
C4A.9 Merkel cell carcinoma, unspecified
C44 Other and unspecified malignant neoplasm of skin
C44.0 Other and unspecified malignant neoplasm of skin of lip
C44.00 Unspecified malignant neoplasm of skin of lip
C44.01 Basal cell carcinoma of skin of lip
C44.02 Squamous cell carcinoma of skin of lip
C44.09 Other specified malignant neoplasm of skin of lip
C44.1 Other and unspecified malignant neoplasm of skin of eyelid, including canthus
C44.10 Unspecified malignant neoplasm of skin of eyelid, including canthus
C44.101 Unspecified malignant neoplasm of skin of unspecified eyelid, including canthus
C44.102 Unspecified malignant neoplasm of skin of right eyelid, including canthus

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.