C96.21

Aggressive systemic mastocytosis

Billable / specificHCC V28 21

C96.21 is a billable, specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes in FY2027.

Inclusion terms

Note: Functional activity
Note: 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.
Note: Morphology [Histology]
Note: 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.
Note: Primary malignant neoplasms overlapping site boundaries
Note: 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.
Note: Malignant neoplasm of ectopic tissue
Note: 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).

Not coded here — never report together with this code.

indolent mastocytosis (D47.02) (from C96.2)
mast cell leukemia (C94.30) (from C96.2)
mastocytosis (congenital) (cutaneous) (Q82.2) (from C96.2)
personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues (Z85.79) (from C96)

Not included here — may be reported together when both conditions exist.