Comparison of Referring and Final Pathology for T-Cell Lymphomas in the NCCN

T-cell lymphomas (TCL) are an uncommon group of diseases recently updated in the WHO classification. Accurate diagnosis requires immunophenotyping and molecular techniques. Diagnostic accuracy of TCLs utilizing the WHO classification has not previously been evaluated.

The NCCN NHL database prospectively collects clinical, treatment, and outcome data for patients seen at 7 comprehensive cancer centers. Using this unique resource, we evaluated diagnostic concordance between referring and NCCN centers for TCLs, including peripheral T-cell lymphoma, NOS (PTCL NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK-positive anaplastic large cell lymphoma (ALK+ ALCL), and ALK-negative ALCL utilizing pathology reports, immunohistochemical stains, flow cytometry, fluorescence in situ hybridization/cytogenetics, T-cell gene rearrangement, and progress notes.

Of 98 eligible patients enrolled from April 2007 to March 2011, 38 (39%) cases were concordant and 60 (61%) were non-concordant. Among non-concordant cases, 34 (57%) had a provisional diagnosis before referral, 6 (10%) were discordant with no additional studies performed, 17 (28%) were discordant with additional studies performed, and 3 (5%) required an additional biopsy. Concordance was highest for ALK+ ALCL at 73%, while the remaining subtypes had low concordance: PTCL NOS 28%, AITL 28%, ALK- ALCL 47%. In 13 (13%) discordant cases (referral diagnosis was benign, a B-cell NHL, or ALK status was undefined) patients may have experienced a significant change in treatment with pathologic reclassification.

In patients with TCL, the likelihood of a concordant final diagnosis at a referring institution was low. Among non-concordant cases, the majority were referred with provisional diagnoses, and many referral diagnoses were discordant. Establishing a precise diagnosis is critical for prognosis and impacts both therapeutic decisions and clinical trial enrollment. As current and future therapies, such as brentuximab vedotin, target subsets of TCLs, our data suggest that all suspected TCLs may benefit from evaluation by an expert hematopathologist.

Kaminski:Allos: Consultancy, Honoraria.