C84.ACutaneous T-cell lymphoma, unspecified

C84.A is the ICD-10-CM diagnosis code for cutaneous T-cell lymphoma, unspecified. It belongs to category C84 (mature T/NK-cell lymphomas), block C81-C96 (malignant neoplasms of lymphoid, hematopoietic and related tissue) and chapter 2 (neoplasms). It is a header code, so it can't be reported by itself; one of its 11 subcodes must be used instead.

Within C84, choose C84.A (Cutaneous T-cell lymphoma, unspecified) only when documentation doesn't support a more specific option: mycosis fungoides (C84.0), Sezary disease (C84.1), peripheral T-cell lymphoma, not elsewhere classified (C84.4), Anaplastic large cell lymphoma, ALK-positive (C84.6), Anaplastic large cell lymphoma, ALK-negative (C84.7), unspecified (C84.9) and other mature T/NK-cell lymphomas (C84.Z).

To report this condition, pick the subcode that matches the documentation: C84.A0 (unspecified site), C84.A1 (lymph nodes of head, face, and neck), C84.A2 (intrathoracic lymph nodes), C84.A3 (intra-abdominal lymph nodes), C84.A4 (lymph nodes of axilla and upper limb), C84.A5 (lymph nodes of inguinal region and lower limb), C84.A6 (intrapelvic lymph nodes), C84.A7 (spleen) and 3 more.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.