Lennert lymphoma (LeL) is a variant of peripheral T-cell lymphoma, not otherwise specified. Few clinicopathologic studies have investigated LeL, which is a rare disease. Here, we analyzed the clinicopathologic features of 26 patients with LeL to identify potential prognostic factors. Neoplastic cells positive for CD4, CD8, CD4/CD8, TIA-1, and granzyme B were observed in 21 (80.8%), 4 (15.4%), 1 (3.8%), 4 (15.3%), and 0 (0.0%) patients, respectively. Regarding follicular helper T-cell (TFH) markers, neoplastic cells positive for programmed cell death-1 (PD-1), CXCL13, CD10, and BCL6 were observed in 14 (53.8%), 13 (50.0%), 1 (3.8%), and 0 (0.0%) patients, respectively. Patients with positivity for at least 1 TFH cell marker (PD-1, CXCL13, CD10, and/or BCL6) were defined as being TFH cell marker–positive (n=15) and had a worse prognosis than TFH cell marker–negative patients (n=11) (P=0.011). Clinicopathologic characteristics did not differ significantly between TFH cell marker–positive and marker–negative LeL patients. Moreover, prognosis did not differ significantly between TFH cell marker–positive LeL patients and patients with angioimmunoblastic T-cell lymphoma (AITL) (n=42). Nevertheless, as compared with AITL, TFH cell marker–positive LeL was associated with significantly lower frequencies of B symptoms, skin rash, high-intermediate-risk or high-risk international prognostic index values, expanded follicular dendritic cell meshworks, polymorphic infiltrate, clear cells, and positivity for CD10 and BCL6. Although it may be difficult to definitively distinguish between TFH cell marker–positive LeL and AITL, our results suggest that TFH cell markers are useful for identifying LeL patients who will experience unfavorable outcomes.