C96.21: Aggressive systemic mastocytosis
C96.21 is the billable ICD-10-CM diagnosis code for Aggressive systemic mastocytosis. It is a fully specified code, so it can be reported on a claim (subject to clinical documentation and your payer's rules).
Frequently asked questions
What is ICD-10-CM code C96.21?
C96.21 is the ICD-10-CM diagnosis code for Aggressive systemic mastocytosis. It belongs to category C96 (Other and unspecified malignant neoplasms of lymphoid, hematopoietic and related tissue).
Is C96.21 a billable code?
Yes. C96.21 is a billable, fully specified ICD-10-CM code, so it can be used on a claim (subject to documentation and payer rules).
What category does C96.21 belong to?
C96.21 is part of ICD-10-CM category C96 — Other and unspecified malignant neoplasms of lymphoid, hematopoietic and related tissue, which has 22 billable codes.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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