Anaplastic large cell lymphoma, ALK-positive, unsp site

This code identifies a specific type of non-Hodgkin lymphoma characterized by large, anaplastic cells and the presence of the anaplastic lymphoma kinase (ALK) gene rearrangement. It represents a malignant neoplasm of T-cells or null cells with distinct pathological features. The "unspecified site" indicates that the primary location of the lymphoma has not been documented or is unknown.

Use this code when documentation clearly states a diagnosis of ALK-positive anaplastic large cell lymphoma, and the specific anatomical site of involvement is not specified or is unknown. This diagnosis is typically confirmed through biopsy and immunohistochemical staining for ALK protein, along with genetic testing for ALK gene rearrangements.

• Ensure documentation explicitly states "ALK-positive" for this specific code; otherwise, consider C84.7- for ALK-negative or unspecified ALCL.
• If a specific anatomical site is documented (e.g., lymph nodes, skin, bone), a more specific code from the C84.6- subcategory should be used.
• Always sequence this code as the primary diagnosis when it is the reason for the encounter, unless another condition is clearly the principal diagnosis.